What is the difference between an Olds 'big block'
and 'small block'?
The problem is that the terms "big block" and "small block" have no
formal definition. The terms most likely came into being when Chevy introduced the Mark IV
engine family (396-427-454-etc) after producing the small block motor for years. The two
completely different engine families led to the big block-small block nomenclature, which
has been extended to most other auto manufacturers. In some cases the use of these terms
is completely erroneous, as with the use of "big block" in conjunction with
Pontiac, for example (all Pontiac blocks are externally the same size). Others, such as
Ford, have multiple, non-interchangeable big block and small block families (why am I not
surprised that Ford serves as the perfect example here). I've even heard the terms used to
refer to engines other than V8s (such as the "big block" BMW straight six).
In the case of Oldsmobiles, conventional terminology refers to the low deck motors
(260-307-330-350-403) as small blocks and the tall deck motors (400-425-455) as big
blocks, though in reality both are the same basic engine architecture with the primary
difference being deck height (Chevy, for example, makes tall deck big block motors for
truck engines, but these are still called big blocks). The first generation Olds V8s (303
through 394) really never got the big/small designation, probably because for virtually
their entire production run there was only one block size.
How do I determine the year of manufacture of my 455
The only way to determine the year is to check the VIN-derivative. This number is
stamped on the pad on the driver's side front corner of the block directly below the
number one spark plug. Note that the pad where the number is stamped is on the block, not
the head, so look just below the deck surface. The number should take the form of:
3 = Oldsmobile division
1 = year of manufacture (1=71, 4=74, 8=68, etc)
M = manufacturing plant (M=Lansing, X=Kansas City, etc)
xxxxxx = last six digits from VIN of car in which motor was originally installed
If there is no VIN-derivative stamped on the pad, the block is probably a service
replacement unit. If the number does not take this form and has an "L" in it,
it's a marine motor.
Is there a way to determine if the engine matches
There are no VIN on these years...just unit no. and date codes and as such you can only
make sure the motor and external parts are correct and manufactured in the same
time-frame. Since the '67 was still a package car it makes it easier for people to change
the motor and other components.
I'm swapping engines in my 442. What brackets/mounts
First, the distance from the motor
mount bolt holes on the block to the crank centerline is the same on both big and small
Second, for 1968 and earlier cars, the frame mounts AND motor mounts are the same for both
big and small blocks.
On the 1969-1972 cars, different frame AND motor mounts were used on big and small blocks.
This is NOT due to the differences in the block but instead due to a redesign to the
rubber motor mount to provide an internal "fail safe" feature that retained the
motor even if the rubber broke. This redesign caused the rubber mount to be taller, which
required the frame mount to be redesigned.
Here's the important part to remember:
So long as you use motor and frame mounts as matched sets - that is, big block motor and
frame mounts or small block motor and frame mounts - either a big or small block will bolt
in with no problems. The crank centerline will be in the same place relative to the frame.
You will definitely have a problem if you try to mix big block motor mounts with small
block frame mounts (or vice versa). They will not line up properly and will need to be
forced into place. If you sit the BB and SB motor mounts side by side, you'll see the
difference in them. With the SB mounts on the BB, it'll raise the engine up in the chassis
about 3/4" or so. Either use small block motor mounts with small block frame
mounts or big block motor mounts with big block frame mounts.
Note that the redesigned big block motor mounts ARE a better design, but I've installed
many big block Olds motors using the small block mounts and had no problems with the
rubber cracking, even when racing. If you go this route, just be sure to inspect your
motor mounts periodically (as you should anyway).
The external dimensions and bolt holes on all 330/307/350/403/400/425/455 Olds
engines are the same. If you're using a Toronado 455, you'll have to find brackets from a
RWD car. All of the RWD V8 brackets are designed to fit both big and small blocks; some
have two sets of holes, others mount such that the extra deck height doesn't matter.
(However, the Toronado brackets are different due to the low hoodline of that car.) The
prime dimensional difference is the height/width of the big blocks versus the small
blocks. However, modifications will probably be required to the alternator bracket...and
problems could be encountered if you attempt to put an R-4 A/C pump on the 455. There is
no such bracket for this unit. You can take two brackets off a 350 and cut them in two and
splice them together to achieve the correct height. I doubt that you will be encountering
this, I just threw it in for kicks.
Big block frame mounts must be used with big block motor mounts, small block mounts
with a small block. Either will interchange, but mixing the two will result in your engine
sitting higher in the engine bay. The main motor mount bolt holes between the two won't
line up either. I have the SB motor mounts on my BB and have not had any clearance
problems. (It can actually help with the clearance on of deeper aftermarket oil pans.)
Basically, since the external dimensions/bolt-holes of the two styles are identical, when
you swap from a small block to a big block, just use the same frame and motor mounts from
your original setup. If you purchase new mounts, be aware that some parts outlets have the
same part number for the BB and SB mounts, so beware...you might get lucky, but they ARE
different. If you go in and ask for a motor mount for a '65-'68 big block car, you'll get
the taller '69-'72 mount, which will not work. There are so few of these older cars on the
road that the big parts manufacturers don't care to investigate these problems. The bottom
line is to always bring the old part when possible and compare.
Swapping from a small-block to a big-block - If you're
swapping in a Toronado 455, you need to use the accessory brackets, pulleys, and water
pump from your small-block. You'll need belts for a 455 in a Cutlass. You'll need to use
the oil filter adapter from the 350. You'll also need to either get a high-torque starter
or swap the nose from your 350 starter onto the Toro starter (your small-block starter
will probably work, but unless you've changed it, it's a low-torque unit that will be
marginal on the 455). Yes, the Toro oil pan will fit your chassis. Finally, yes, the
intake and headers will bolt on.
NOTE: The 307 uses different brackets that fit a small block only. You'll need to get
an early set of brackets...any '68-'76 brackets should work. They don't need to be from a
455. If you're determined to make the 307 brackets work, here's what you need to know:
The power steering bolts to the block so you're OK with that...even uses the belt for
the 307. The alternator bolts to the head, so no problem there except for that a longer
belt is needed. The alternator bracket bolts to the power steering bracket and all you
need is a longer bolt and nut and a spacer. You can use a 3/4-inch long piece of 1/4-inch
pipe, which will work fine and is hard to see. The A/C presents some real problems but
they are not insurmountable. The A/C brackets bolt to both the water pump and the head. If
you lengthen the water pump bracket the compressor ends up sitting way too high and will
not clear the hood. Thus, you'll have to lower and move the compressor outward. This
clears both the hood and the head. It'll take some trial and error to get the brackets in
the right place and welded up. However, the belt will end up being very long and when you
get on it hard the belt will probably get tossed.
Want a cheap engine torque strap? Drilled a 1/2" hole all the way through the
drivers-side motor mount and put a grade 8 bolt/nut though it and tighten it down. You'll
have to clearance the frame pad.
To all you guys swapping a V8 Olds into a 231-V6 car: According to GM, the metal frame
mounts that are bolted to the cradle are different between the V6 and V8. The V6 mounts
are taller. Just something to keep in mind.
BTW, GM lingo calls the rubber engine mounts "brackets" and the metal frame
Motor Mount Myths
Largely by Joe Padavano but Published
without his Permission
from the Oldszone
question of which motor mounts to use when replacing an A-Body (F-85,
Cutlass, Cutlass S, Cutlass Supreme, 442) small block with a big block
comes up frequently on the Olds mailing list. Here's
motors (big and small block) have the motor mount bosses in the same
location relative to the crank centerline - the only difference is the
deck height. The year of the block (or the displacement for that matter)
has absolutely NO effect on the type of motor mount to use. The only thing
that matters is the matching frame mount. You must use the motor mount
that matches the frame mount in the car.
If it was
originally a small block car and you do not intend to change the frame
mounts, get small block motor mounts. These will bolt to the big block and
will allow the engine to sit in the exact same location relative to the
frame as it would have in a factory installation. Alternatively you could
use matching big block motor and frame mounts, but for all this extra
expense and effort the engine will still be sitting in the same location.
engine mounts with small block frame mounts - OK
big block engine mounts with big block frame mounts - OK
small block engine mounts with big block frame mounts - the engine will be
1-2" too low
big block engine mounts with small block frame mounts - the engine will be
1-2" too high
the way, that the big block is about an inch taller than the small block
when measuring from the crank centerline to the carb flange, so even if
you the matching mounts, the air cleaner and valve covers will be higher
in the engine compartment. The crank centerline, fan, and flywheel will
all be in the same location as they were with the small block.
thing you need to remember is that the rubber motor mounts and the metal
frame mounts need to match. Nothing else matters.
Power catalog (1982) is incorrect and shows:
270-2261 - 1964-69 all V8 exc. w/400
270-2261 - 1970-72 all 350
270-2328 - 1970-72 all 455
270-2380 - 1973-77 all 260, 350R, 455
270-2328 - 1979-80 all 260P and 350N Diesel
270-2380 - 1979-80 all Cutlass Supreme and Calais 350R
270-2380 - 1980 all 307
270-2380 - 1978-81 all 260F gas
270-2328 - 1981 Cutlass Cruiser Station Wagon 260F gas
270-2328 - 1981 all 350N Diesel
This is a
classic example of an incorrect catalog listing. The problem is that the
64-69 small block and 65-68 big block motor mounts are identical. The 1969
400 mounts (and 455 for the 69 H/O) were changed to the taller design used
on the 69-72 cars. The small block mounts were changed in 1970. The
listing should say "1964-69 all V8 exc. 1969 w/400".
1964 - 1968
small and big block motor mounts 270-2261
1969 - 1972 small block motor mounts 270-2261
1969 - 1972 big block motor mounts 270-2328
1973 - up small and big block motor mounts 270-2380
started in 1969. The original motor mounts used on the earlier cars were
simply two pieces of metal with rubber molded in between - there was no
interlocking feature. GM went through a massive recall in the 60s to
repair broken motor mounts of this design. As a result, the big block
cars, starting in 1969, got the interlocking design. Unfortunately, this
design required the motor mount to be taller, so the frame mount was
changed to move the cross bolt (the bolt that attaches the motor mount to
the frame mount) further down on the frame mount. The 64-68 (and 69 small
block) frame mounts have the cross bolt hole about 1 1/2" down from the
centerline of the two top bolts that attach the frame mount to the
crossmember. On the 69-72 big block mounts, this dimension is about 2
1/4". The rubber motor mounts are correspondingly different (the 69-72 big
block motor mount is about 1" taller than the 64-68 V8 (and 69 small
Olds redesigned the small block mounts to also incorporate the
interlocking feature, but did this in a way that did not require the cross
bolt to be moved. Thus the 70-72 small block frame mounts still use the 1
1/2" dimension. There is, however, a difference between the 70-72 small
block mounts and the 64-68 V8 (and 69 small block) frame mounts. The
raised pad is smaller and biased towards the top of the mount. Thus, I do
not think it is possible to use the 70-72 small block motor mounts on the
64-68 frame pads. On the other hand, it probably _is_ possible to use the
68-68 V8 (and 69 small block) mounts on the 70-72 frame mounts.
starting in '73 Olds realized that there was no
reason to maintain two different motor mount designs and went back to
using a common motor and frame mount design on both big and small blocks.
more word of advice. Don't rely on any catalog, other than the factory
parts catalog, to tell you what motor mounts fit where. As I noted in a
prior post, the Sealed Power catalog is flat wrong.
Identifying Frame Pads
You can check by measuring from the center of
the two top bolts that hold the mount to the frame to the center of the
cross bolt that attaches the frame mount to the motor mount. The big block
frame mounts will measure about 2 1/4", while small block mounts will
measure about 1 1/2". Whichever ones you have (big or small block), get
the motor mounts to match.
bolting the motor mounts to the block, there are three tapped holes on
each side. The front two are for full size cars, the back two for Cutlii.
Also, when you unbolt the Toro front motor mount (you don't need it for
RWD applications), be sure to reinstall the timing tab.
1970-earlier B/C body cars use a motor mount that is completely different
from the A-body mounts. The rubber mount has a threaded stud that fits
into a hole in the frame. A nut is installed from the underside. One other
wrinkle is that some B/C body cars DO use a 1" shim under one motor mount
(see notes on the Cutlass offset engine myth.) If the shim is there on the
350, use it in the same place on the 455. Also, note that B/C body motor
mounts bolt to the forward two of the three bosses on each side of the
block. The A-body cars use the rear two bosses.
Q) Are the
69 onward small block motor and frame mounts exactly the same as the early
"one size fits all V8's" units.
A) The answer unfortunately is no. The 69-up small block mounts are not
the same as the 68-down universal mounts. The net combination of matched
motor and frame mounts for a specific year is always the same, but the
individual parts may be different from year-to-year.
Q) What is
the earliest year motor and frame mounts that will put a V8 into an
A) 1964 330 motor and frame mounts used as a matched set will install any
64-up (except, of course, the 394) Olds V8 in a 64 A-body. Ditto for 65,
there any better quality mounts or mounts to avoid?
A) General concensus is that the G.M. rubber mounts (made in the U.S.A.)
are the best rubber ones. Also, for reference, the Mondello SM300 mounts
appear to be solid versions of the Sealed Power 270-2261 mounts and
SM400's appear to be the solid version of the 270-2328.
I hope this
has been helpful.
Are there any differences between Oldsmobile V8 water
There are actually three different Olds water pump lengths. The measurement you care
about is from the gasket surface of the pump (with the gasket removed) to the front face
of the flange that the spacer or fan clutch bolts to. The three pump sizes are:
- 5.947" - all Olds motors with A/C
- 5.572" - B and C body without A/C
- 5.072" - A and E body without A/C
Note that the "with" or "without A/C" really applies to the pulley
set that you are using. The pulleys and accessory brackets are designed to match the pump,
so if your car had A/C and you removed it but are still using the A/C accessory brackets
and pulleys, get the A/C pump.
One other item to note is that some HD cooling cars used the longer A/C style pump even
though they did not have A/C.
Will a cam designed for a 330 will work in a 455?
No, but only because the 330 has the 45-degree lifter bank angle, vs the 455's
39-degreee bank angle. Everything else (cam bearing diameters, cam length, timing gear) is
the same between big and small block Olds motors, but using a 45-deg cam in a 39-deg motor
will result in at least one bank of cylinders having their valve timing grossly out of
I want to install an adjustable valvetrain.
What do I need?
Small block Ford 3/8" stud mount rockers interchange with Olds. AMC 3/8"
rockers also interchange. You will need the Competition Cams 5/16" lower
stud/3/8" upper stud and guide plates for mounting the roller rockers. You MAY also
need custom/adjustable pushrods.
Is it really important to install hardened valve
seats in a street motor?
Lead in gas has two functions: raise the octane level and lubricate the exhaust valve
seats. If lead is missing in the fuel, the exhaust valves hammer away at the seats. The
lack of lubrication wears the seats. This is called valve recession. The worst condition
is a constant high RPM operation. If this motor has been run for years on unleaded gas,
then there is a good chance that the recession is already in progress. I would recommend
that you install them.
First, they will need to be hot-tanked,
Magnafluxed, and checked for straightness. I
always go for new iron valve guides and hardened exhaust seats. Make sure the machine shop
knows and uses the appropriate seat for Olds heads. They should be about .22" thick.
Thicker ones will result in cutting into the coolant passages.
Be absolutely sure you know the difference between bronze 'guides' and what most shops
use bronze 'liners'. The liners are bronze but are just that...'liners'. I myself prefer
an actual replacement guide. These guides are sometimes called 'thin wall'. In order to use
the 'thin wall' type the old guide must be bored out, this process is done on a seat and
guide machine. A "thin wall" cast iron guide is usually good for the life of the
rebuild. A bronze 'thin wall' is more suited for racing and high load
probably looking at double the cost for the bronze 'thin wall' guides over the cast iron.
Anything else will depend on conditions and what you want done. If the heads are warped or
corroded, something will need milled. If you are using a stock rocker arm setup, you will
need to have the valve stem height set (tips of the stem are all at the same correct
height). Your valve springs are probably worn out, so you should replace them with springs
to match your camshaft.
Stainless steel valves are always better than the stock steel valves. The stock valve
guide "seals" are pretty cheap, so I like to use Perfect Circle VS-100 which is
a rubber seal with a Teflon insert in the hole.
There are a couple of ways around using hardened seats in a street motor. One is to
simply run leaded fuel -- I get mine from a little airport in five gallon jugs. Low lead
100 aviation fuel has WAY too much lead for cars, so don't run it straight up -- I mix
about five gallons in a twenty gallon tank. If your seats were cut during the valve job,
its too late for this trick, but hardening of valve seats occurs naturally when a motor is
run-this is called "work hardening". If you can get by with just a lap, no major
grinding, and run stainless valves (they don't retain crud the way a steel valve does), you
can get by without hardened seats on a STREET motor-heavy runs at the strip not allowed.
This has worked many a time for me also. The main thing to remember is not to hammer on
the motor too hard unless you got some leaded fuel in the tank.
I want to install exhaust headers. What should I get
and what problems might I see?
For a lower tuned daily driven car use headers with smaller diameter, longer length
primary pipes. 1.75" primary pipes are probably best and if you can get them 40"
long pipes. The smaller tubes keep the hot gasses from expanding which keeps the velocity
up, the length keeps it from hitting the collector and expanding until the next exhaust
pulse is ready (low RPM). When the pulse finally hits the collector and exhaust pipe the
created low pressure in the next tube will pull exhaust from the next cylinder reducing
backpressure. There are 1.875" and 2" primary headers but these will reduce the
scavenging effect at lower RPM (unless you are pushing a brutal amount of air at low
RPM...say with a blower or something). High RPM engines are generally more concerned with
flow since an engine spinning at high speeds will impart substantial velocity to the
exhaust gasses anyway.
There have been reported problems with driver's-side header installations on '66-'67s,
with reports ranging from interference from the steering shaft, frame, and even the
To facilitate the installation of headers on virtually every situation -
- Move the brake distribution block to the top of the frame rail
- Grind about 3/8" from the rear of the lower driver side control arm mount
- Grind down a portion of the passenger side upper a-arm.
- You'll have to remove the starter and oil dipstick tube, and you might also have to put
a small dent in one header tube.
- The passenger side might require temporary removal of the oil filter housing for
Hedman headers are a good fit, not hanging too low. Swap-meet Blackjack headers are
reported to fit well. Since then, Dynomax purchased Blackjack, so their headers are a
match...plus, you can get them aluminum-coated.
Which cast iron Olds exhaust manifolds can I use
when doing an engine swap?
Big block stock cast iron exhaust manifolds are longer due to the increased block
height. In other words, they reach down farther. When swapping exhaust manifolds, you
could possibly run into problems with interference with the starter or oil filter, and/or
the outlets may be in an awkward location. Be sure to compare before installing.
All small block exhaust manifolds are of a small, open plenum design. They are poor
performers for a 350 and will be really restrictive for a 455.
use the 307 exhaust manifolds because the
outlets were a bit bigger than the 455 manifolds.
You can take your old trusty die grinder and
slightly port the manifolds and remove casting flash etc. inside of them.
Second, if you're keeping the small block manifolds because you want to use the 350
exhaust pipes when swapping in a 455, forget about it. The 455's taller deck height will
prevent the pipes from fitting (they'll hit the floorpan at the base of the firewall). You
stand a better chance of getting the pipes to fit if you use the correct A-body big block
Will a big block Olds oil pan fit my small block?
Yes, they will work just fine...the only difference is that the big block pans have an
additional bulge just forward of the sump, presumably to clear the longer crank throw
while still providing enough clearance for oil drainback. The 455-equipped Toronado pan
will physically fit and will increase oil capacity by one quart, but it's a poorly
designed pan for a rear-wheel-drive car. The Toro pan has a front hump that looks like it
traps about a quart of dirty oil. So, yes it has a 5 quart capacity (6 w/filter) but you will never get the last
quart out. AND, there is no baffle on the bottom, so you will have to add one. I would go
aftermarket if I wanted a larger capacity pan. If you DO decide to go with the Toro pan,
remember to get the pickup off the pump. There is a difference between that and a standard
Another feature of the big block oil pan is the tack-welded oil baffle. It sits on the
edge of the sump portion of the pan. Under braking or hard acceleration it helps to keep
the oil in the large pick-up area of the pan. Most small block pans do not have a baffle
to help keep the oil in the sump area. This feature alone is worth using a big block pan
on a small block application.
FYI: The 455 pan will fit the 350 but the 350 pan will not fit the 455 motor. The crank
will hit the bottom of the 350 pan.
I've heard about cylinder head porting for
better performance on my Olds. Please explain.
For a street vehicle the last thing you want to do is enlarge the port area. This will
reduce air velocity at low engine speeds, and decrease the cylinder's volumetric
efficiency (VE) which means the cylinder won't fill all the way until the RPM is pretty
high. The basic idea is to make the air flow smoother with less turbulence, there are
various ways to do this. Remove all the sharp edges. There are specific key areas to do
this. The 2nd most important area on the intake side is to reshape the valve guide boss
into a more aerodynamic shape, usually referred to as "tear dropping", because
that's what it resembles once finished, and to smooth the area where the bowl meets the
valve seat "blending". On standard heads the bowl area does not make a smooth
transition to the valve seat which causes lots of turbulence, inhibiting air flow. There
are typically sharp edges on the short turn side of the runner, sort of like steps. These
can be smoothed but this is not usually done for standard street use. Usually its a good
thing to polish the combustion chamber to help prevent pre-detonation when running high
compression. With a totally smooth surface, you don't develop as many hot spots. On the
exhaust side its almost mandatory to remove those AIR bumps from the top of the exhaust
port, its also a good idea to polish the runner as much as possible to reduce air
friction. Basically the easier the air can travel through the runner the less power your
engine has to use to force the air out of the cylinder leaving more power to turn your
crankshaft. You probably shouldn't polish the intake runner though. If you are porting the
heads for street use you'll want to do the bowl to valve seat transition, valve guide
boss, exhaust port. You could call this a "street/strip" port I guess. A pocket
port usually would just entail the doing the bowl area. A full port job usually means
doing all what I have mentioned plus enlarging the ports to flow more at higher RPM.
Strictly for race engines I assure you. Now to the cost, its fairly expensive to get a
street port. I have seen street ported heads going for as much as $1000 (depends on the
shop). The best thing you can do is give them a list of what you want and get them to
quote you a price.
I'm replacing my stock cam with a performance unit. How do I check preload, to ensure longer pushrods aren't needed?
Hydraulic lifters are usually supposed to have .050"-.080" pre-load. One
simple way to check preload is to tighten the rocker arms down and measure the clearance
between the lifter plunger and its retainer ring. You will need some sort of gauging wire
to check that. Another way to check it is to tighten the rocker arms until there is zero
lash and then see how much further the bolt turns before the pedestal contacts the head.
Find zero lash by spinning the pushrod while tightening the bolt. As soon as there is
resistance to spinning the pushrod, you have found zero lash. With a rocker arm ratio of
1.6, the bolt will need to be screwed in about .050" further to get .080" lash.
With 5/16"-20 bolts, that will require that the bolt be turned one more complete turn
before the pedestal bottoms. You could also use a feeler gauge to check for .050"
clearance between the pedestal and head when you have zero lash.
What does the PCV valve do on my Olds, and is it
All internal combustion engines produce blow-by gases- fuel and oil vapors that get
past the rings and must be removed from the engine to keep oil reasonably clean and free
of condensation and other impurities. The Positive Crankcase Ventilation valve
accomplishes this by sucking the blowby gases back into the intake manifold under vacuum
and reburning them in the engine. There can be either open or closed PCV systems. Open
systems use a vented oil fill cap or breather filter to allow fresh air into the engine so
it doesn't vacuum lock. Closed systems (used on all Oldsmobiles since 1968 and California
ones since 1962) get their fresh air from inside the air cleaner housing thru a tube and
breather filter on the valve cover. This is so blowby gases and oil vapor can be sucked
into the engine thru the air filter element and burned instead of going into atmosphere.
Earlier cars (pre 1962) had road draft tubes extending from the top of the engine to the
bottom of the car. Airflow over the open end of the road draft tube induced a vacuum in
the engine and pulled impurities out of the engine right into the atmosphere.
So yes, you need a PCV valve or some other way to evacuate blowby gases. It keeps oil
cleaner, reduces sludge, and as long as the crankcase is under vacuum from the PCV system,
the outside of the engine stays cleaner. If you ever see an engine that the PCV wasn't
working, it'll be coated in oil that blew past all the seals.
The PCV valve regulates the amount of air being drawn from the crankcase. At high manifold
vacuum, the valve seats to limit the flow. At low vacuum (WOT), the valve unseats reducing
the restriction to allow a comparable amount of air to flow with the lower vacuum source.
High vacuum, high restriction. Low vacuum, low restriction.
I believe the closed system was also introduced to reduce emissions on aging vehicles. The
PCV cannot keep up with a tired engine with lots of blow-by, especially at WOT. Oil in the
air cleaner housing is a tell-tail sign of a dead engine. The open system will let excess
blow-by to the atmosphere.
If you look at a vacuum gauge, they usually have a mark at the low end for PCV checking.
The crankcase should normally be a few inches negative. Connecting a vacuum gauge to the
crankcase is a good determiner of engine health (stock engines).
W-30s DO have a PCV valve. It is plumbed into a hole in the intake manifold that goes
into the lifter valley.
Most '67s I've run across had a PCV valve in one valve cover and a breather in the
other. As far as which one goes where, it depends on whether the car has the Climatic
Combustion Control system (huge, weirdly shaped air cleaner with twin intakes), cruise
control or California emissions package. Also, factor in that there may have been a
difference in closed and open PCV systems, which having a breather, yours is open. Closed
systems took their fresh air from the aircleaner via a tube. Functionally, it won't make
any difference which side the components are on.
The aftermarket thermostat housing on my
engine leaks. What can I do?
Chrome aftermarket water necks are frequently warped. Get a piece of fine wet/dry
sandpaper, put it on a piece of glass (for flatness) and run the base of the water neck
back and forth over it. If the sandpaper does not evenly sand the bottom of the water
neck, then you can see where the warpage is. If the neck is aluminum or pot metal,
continue sanding until flat. If it's cast iron this might take a while and you may want to
get another. Then be sure to use Permatex sealant on both sides of the gasket when
installing the water neck.
If the sandpaper trick shows that the neck is flat, you've got a problem with the
I'm seeing a lot of condensation from my 442's
exhaust pipe. What's the story?
A lot of people have the bad habit of starting up their "garage queens" every
week or so and letting them run for only 15 minutes or 20 minutes instead driving them for
at least 30 minutes (or longer). This allows condensation to continue to build up in both
the exhaust system and engine oil...in other words, they're doing their cars more harm
than good. If you drive your car regularly, allowing a full warm-up, and the outside temps
are warm and still had condensation after an hour I might be a little concerned, but it's
only water. If it were antifreeze, it would be white smoke coming out your exhaust, not
liquid (you're not running straight water in the radiator are you?). Cars that sit really
need to be started and run long enough for the condensation to evaporate from the
crankcase and the exhaust system. Don't be a sissy...let those four barrels breathe once
in a while! In other words, I wouldn't be too concerned with the condensation, but I'd
still keep an eye on it, just in case.
Incidentally, this phenomenon is the single fastest factor is an exhaust system rusting.
For cars that are stored for any period of time, it's always a good idea to stuff some
rags into the exhaust pipe to seal them, or to slip a plastic sandwich bag over the
tailpipe and secure with a rubber band.
How do I install a replacement oil dipstick tube?
Try putting it in the freezer for a few hours. As the metal gets down toward zero
degrees it'll shrink and you should be able to tap it in without damaging it. Once it
warms up it'll expand and seal itself properly. If you still have trouble inserting the
tube after freezing it, you might have to sand the round part of the tube that goes into
the block down just a bit. Then stick a bolt inside the tube and use a small ballpeen
hammer to tap it in.
How do I hook up my aftermarket tachometer?
If it's a Sun Super Tach II and unless they changed it-White is the internal light. Red
goes to 12v source. Black goes to chassis ground. Green is the trigger wire which has to
be connected to the coil (-).
- Connect the GREEN wire to the coil (-) post.
- Connect the RED wire to a switched 12v circuit at the fuse block (spare blade terminals
labeled IGN or ACC).
- Connect the WHITE wire to either the dash light circuit (tap in on load side of the INST
LPS fuse) or an ACC terminal.
- Connect the BLACK wire to a good chassis ground under the dash.
Try to stay away from splicing into wires behind the dash. It makes a fire hazard. Use
insulated terminals and special fuse taps. It looks and works better.
My 455 detonates (knocks) any time I punch it. The motor was bored .030,
TRW 10.50 pistons, JM20-22 cam, "C" heads with hardened seats, perf. intake with
800cfm carb, MSD distributor and box, and AC RS45 plugs set at .045. It does have a more
or less stock exhaust system. I run 92-octane gas with a bottle of 104 octane boost per
- With 10.5:1 compression, 92-octane will ping pretty good. You will need to go to a local
race track or airport and get some GOOD gas, like 114-octane leaded. Put 5 gallons in
every tank with some 92-octane premium.
Make certain the engine is running cool...with that much compression, a 160-degree
thermostat and a cooling system which can keep it in that range is recommended. Also it's
better that the carb be getting some kind of cool outside air and not sucking the hot
- The spark plugs mentioned are probably too hot for that much compression. R45S plugs are
more suitable for 8.5 or 9:1 compression. Try some R44S or R43S plugs to cool it down a
Try running the car with the vacuum advance disconnected first. To check timing properly
get a dial advance timing light! If you don't know how to use one, ask somebody who does.
You are risking serious engine damage. The MSD is a tunable distributor...read the
instructions and limit your distributor advance to 20 degrees to start with. Select the
spring combination to give full timing advance by 3000 rpm. Put the distributor in the car
and start with around 12-14 initial timing (that's what you read with the engine
idling). Check the timing at various engine speeds, then make sure it does not exceed
34-36 degrees after 3000 rpm. By adding the distributor advance's 20, plus the initial
advance 12-14, you get 34-36 total degrees advance.
Adjust your mechanical advance rate in the distributor, controlled by the tension
springs. You may need to just SLOW down the advance rate of the mechanical advance by
using stiffer springs. The mechanical advance weights are linked together so they always
swing out an equal distance. Thus, the two springs work together, the sum of their force
pulling both weights in. In fact, using two springs of different rates is a common way to
modify your advance characteristics. Can't decide between stiff springs and light springs?
Use one of each to split the difference.
As a last resort, have your carb's air-fuel mixture checked under load (the point at
which it pings). There is a fuel enrichment circuit for acceleration and it may not be
working. Look for about 12:1 air-fuel ratio under acceleration and around 14:1 at cruise.
One last point to keep in mind; my understanding is that TRW rates its pistons based on
a 70cc combustion chamber. The C-type heads you have should be more like 79 or 80
your compression is way less than 10.5, probably closer to 9.5.
rear main seal
A rope seal can work on a race motor if the installer is experienced at seating it
properly but the neoprene seal will always have less drag. In place of the factory rope
seal, use the neoprene rear main seal made by Fel-Pro. (PN BS-6141). This part number
isn't a listed number for the Olds small blocks, but is listed in the April 2000 issue of
Car Craft (page122). This part # is an AERA recommendation.
First, polish the knurling off the neoprene seal to ensure longevity. Install the two
pieces with a 1/4" offset...that is, one side lower than the other in the seal
groove. This will greatly diminish the possibility of leakage. Make sure the lip is facing
the front of the engine and coat it with lube so you don't have a dry start-up. And don't
forget to put a small amount of sealer on the mating surfaces of the rear main cap.
If you can't find the neoprene seal, you have two options:
1) Get the Victor seal for a Ford 429/460. This package lists the following applications:
Ford 429, all '68-'78 460, '79-'81 370, '79-'95 429 and '73-'95 460 trucks.
2) Fel-Pro BS 40032, which is a rubber piece.
Go to a local NAPA store and order part #JV618. It is the correct seal for an Olds 455.
Did all '67s come with a fan shroud?
The radiator fan shroud that was used on '67 A-body models was the same design as '66.
A fan shroud was used when you ordered either C60 car air conditioning or Y76 Heavy-duty
cooling (Y76 was included with CAC). A Cutlass with the L78 442 package would have come
standard with a 2-core radiator and a 4-blade fan, in either an automatic or sycromesh.
One would get the 55-amp alternator, CAC water pump, 6-blade clutch fan, three-core
radiator, radiator shroud and hood seal with C60 and Y76. You could not factory order C60
or Y76 when the car was equipped with a rear axle ratio of 3.90 or lower. The higher
engine burst speeds with the lower axles were of a concern to Olds. This might cause a
problem if the fan or compressor clutch engages at speed. Hence, that was why you could
not get C60 and Y76 on early W30 cars.
The shroud was attached to the upper radiator support on top but used two Z brackets to
attach to the lower support.The shroud had been reproduced
and sold by Year One. Y76 cars are
quite rare, but the pieces to add the option are pretty easy to find.
I want to block off my intake's heat crossover.
What are my options?
Some people argue it is a warm-climate-only modification. If the car is a northern
park-outside driver, I might think twice. Otherwise go for it. There are a few options. You can use the Edelbrock cast iron plugs in the heads. They
work absolutely fine. They do require some custom grinding to fit into the heads. However,
there HAVE been reports of these coming loose and rattling around.
One of the things about
the plugs is they only block the heat from the intake. They do nothing for the
interconnection of the two exhaust ports and the which way should I go?
four exhaust ports. The general consensus is molten zinc is the ticket. Its expansion is
supposed to be similar to the iron. I personally use furnace cement (Irontite brand). You
can blend it nicely in the bowel area easily. I have only had it come loose once and
attribute it to me rushing the job with heat lamps,
possibly creating air pockets. Remember if you
block the risers you will have to come up with an alternative to the factory choke, as
there will be no heat to operate it.
You could also purchase some alloy from Mondello for plugging them. It will have to be
melted and poured in. I've also heard of people using old pistons and melting them and
pouring them in.
What are the overbore limits for a 455?
According to the experts (Mondello and Miller) a 455 block can be bored +.125. However,
I have heard of some people having difficulty at +.060. If you want to be sure, have it sonic tested. That will be able to tell you if your
block can handle it. Blockwise, the older blocks ('68-'72) have a higher nickel content
and so are a better choice for large overbores (as compared to the '73-'76 blocks.)
Are small block and big block Olds headers
No. Due to the taller deck height, big block Olds headers have a greater vertical
dimension than small block headers. Additionally, small block headers typically use
smaller diameter primary tubes.
My radical cam is killing the vacuum to my brakes. What can I do?
Use a vacuum reservoir. This extra reservoir is usually the size of a small coffee can
5X7. It goes between the vacuum manifold line and the power booster. The vacuum
also comes with a check valve. Summit Racing makes several different ones. Purchase the
most basic one and hide the tank up in the driver's fender and hide all the vacuum lines.
You won't be able to tell something was added. It will bring back the power brakes nicely.
Cost of the tank is between $35-$40. GM (and likely others) used them. Mid-'80s
them. Standard Motor Products sells replacements for the factory versions.
Q: I purchased a rebuilt
carb for my '69 442 and was wondering if there is a
rule of thumb for initially setting up the carb.
A1: Do you have
any Olds repair manual for that year? It will tell you all the info you need,
like how to set the float level, choke, and fast
idle. Many of the adjustments on Quadrajets are done
by slightly bending certain linkages. This, too, is covered in the
Chassis Service Manual for your year. Follow their diagrams in sequence, as
making one adjustment can affect others.
The one item that is not covered in the manual (if I remember correctly) is
adjustment of the idle mixture screws -- one of the first adjustments you'll
want to make. The manual doesn't cover this because the factory supposedly
optimized that adjustment for emissions, and they didn't want you monkeying
with it. But if you've changed cams or compression or you're starting out with
a rebuilt carb, it needs adjustment.
As a starting point, turn both idle mixture screws all the way in, then back
them both out 3 turns. With a warm engine (no choke), adjust the idle stop
screw to the specified rpm. Now go back to the idle mixture screws and adjust
them richer or leaner until you maximize the rpm. Always adjust them equally.
Back off the idle stop screw to specification again, then adjust the idle
mixture screws for maximum rpm again, etc. When you've reached the point where
the idle is at specification and further adjustment of the idle mixture screws
only drops rpm, then adjust them 1/4 turn at a time, leaner, until the rpm
drops 50. Then bump the idle back up 50 rpm with the idle stop screw. You want
your idle to be on the lean side of perfect.
I hope I didn't make that sound too complicated. It's not.
Stock Olds 400, 425, and 455ci Cylinder Head Flow Tables
All valve sizes used for baseline flows on intakes were 2.071", except on
the "J" head which had a 2.00" intake. All exhaust valves were 1.625".
All flow tests were conducted at 25" of water.
All flow numbers are stated in CFM (Cubic Feet Per Minute).
BIG BLOCK INTAKE PORTS
Cylinder Head Type
Valve Lift A B C D E F G & Ga H J Ka
.100 80 87 84 87 86 82 76 80
.200 153 155 147 156 149 150 136 148
.300 199 195 203 198 193 197 194 197
.400 220 215 229 214 212 219 210 211
.450 230 220 232 221 218 225 212 218
.500 236 225 236 226 223 229 214 223
.550 239 229 238 228 224 231 214 224
.600 244 231 239 230 225 234 214 225
BIG BLOCK EXHAUST PORTS
Cylinder Head Type
Valve Lift A B C D E F G&Ga H J Ka
.100 46 47 45 46 44 47 46 44
.200 93 92 87 93 91 92 84 89
.300 125 125 120 122 122 124 114 119
.400 137 139 139 136 137 139 118 136
.450 142 144 144 140 142 144 119 141
.500 149 148 149 145 147 149 119 147
.550 151 153 153 149 149 153 120 150
.600 153 157 157 153 152 156 120 152
Q: I believe my
engine has a dead cylinder. How do I find it?
Here's a simple
test that can quickly and cheaply determine the relative performance of an
engine, by cylinder comparisons.
What you'll need:
8 1" to 1.5"
sections of 1/4" carbon impregnated vacuum hose (which loosely translates to
A couple feet of
electrical wire (alligator clips on each end helps, or at least a couple
inches stripped off.)
with an insulated handle (or some other test probe, whatever happens to be
A tach, paper,
and pencil, and stopwatch may be of benefit, too
1: With the engine OFF, remove
each plug wire, at the cap, one at a time.
2: Insert a section of vacuum hose between the
cap's tower and each wire, making sure the wire and hose fit snugly together
3: Repeat steps 2 and 3 until all cylinders
are accounted for ;) You should end up with a set of plug wire extensions
above the cap.
4: Connect one end of the electrical wire to a
reasonable ground location (fender, frame, alternator bracket, etc.
5: Connect the other end to the
You may now start
the engine, and allow it to idle.
Touch the probe (screwdriver) to the vacuum line extensions, one at a time,
for about five seconds at a time. Repeat for each
This shorts out the plug wire, effectively killing the cylinder. Take note of
the amount of RPM drop for each shorting. The higher
RPM drops will indicate a stronger cylinder. If the
RPM only drops a little, or not at all, or increases then you've found a
dead/weak cylinder. The only thing that'll tell you
is that that cylinder is not contributing to the power production of the
engine... It's up to you to determine why. A bad
plug, wire, or mechanicals are all causes, as are vacuum leaks on that intake
By watching the tach and stopwatch, and recording the RPM drops for each
cylinder, you can get a fairly accurate representation of the engine's overall
condition, much like a compression test. If electrical inspections don't
reveal anything, then you may consider compression tests, leakdown testing,
and/or other mechanical inspections.
39-degree angle block
There are a couple
of ways to check for cam bank angle, and if it is a Toro 425 block (probably
applies to all blocks): Find the engine ID number/letter on the shelf behind
the water pump, ahead of the intake, just above the timing chain. Now, at the
RH [passenger] end of this shelf is an upright wall that runs fore-aft. This
means the block is a big block. It should get fatter toward the front. Right
near the top, in the fatter part, there should be a drill spot, at about a 45
degree angle [parallel to the even-bank head bolt holes] and just barely
drilled into the wall or rib, until the diameter got to about 3/8". If that
drill spot is there, then the block is almost w/o a doubt a 39-degree cam
block. Every 1966 to 1967 Toro 425 and 1966 to 1967 442
400 engine I have seen so far had this drill spot and had a 39 degree
cam bank angle. Basically, the way it worked out was that if the early (pre
1968) big block had 0.921 lifters, it was an advanced [for the time] 39-degree
block, and if it had the normal 0.842 lifters, it was an old 45 degree block.
Anyhow, the presence of the drill spot on a pre-1968 big block means a 39
degree block and heads. Easy to spot, too.
B cyl heads
1965 came in
two valve sizes a 2.000 intake and 1.625 exh 80 cc
2 bbl heads and a 4bbl version used on irrigation equipment both have
number 389395 cast in cyl. head, but the irrigation head uses a
2.070 intake and a 1.625 exh
1966 came in
one version 2.070 intake and 1.625 exhaust, same cast
number as 1965 used on 400/425 4-bbl;
all are 80cc. Bank angles
are as follows:
1965 block 389298 45 deg b block 400
1965 block 386525 45 deg a block 425
1966-67 390925 39 deg e block 400
1966-67 389244 45deg d block 425
1966 389244 w/drill spot 39 deg d block 425
1967 390925 w/.375 drill spot 39 deg e block 400
1967 389244 w/.203 drill spot 39 deg d block 425
1967 389244 w/.375 drill spot 39 deg d block 425
So some B heads are
comparable to C heads w/slight modification, but don't
forget c heads also came in two valve sizes a 4bbl version and a 2 bbl