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What engines were available for the Camaro's?
How can I improve performance?
How can I improve
my High Energy Ignition (HEI)?
How do I grease the HEI as
mentioned above?
How can I keep my headers from burning the
spark plug wires?
What camshaft should I get?
What's involved in installing/rebuilding a Quadrajet?
How can I decode the Quadrajet carbs?
How do I
select the right aftermarket carb?
What is the advantage
of a 2-piece timing chain cover?
When was the last year
for the big block?
Were there "big block" and "small
block" Pontiac engines?
What years was the Pontiac 455
available?
What is the the best cam for my Pontiac
455?
Is there a fuel injection manifold available for my
455?
How was the 455 engine different from the Super Duty
version?
How can I tell if a Super Duty 455 engine is
genuine or not?
What is a Ram Air V engine?
How did the
standard 400 and T/A 400 differ from 1977 - 1979?
What are
the best techniques for building up a 400?
What are the
best techniques for building up a 455?
What engines were available for the Camaro's?
The following lists the displacement (cubic inches),
the carburetor type and manufacturer, horsepower, torque, and compression
ratio:
1970 1/2
Disp Carb HP Torque C/R
307 2bbl Roch 200@4600 300@2400 9.0
350 2bbl Roch 250@4800 345@2800 9.0
350 4bbl Roch 300@4800 380@3200 10.25
350 4bbl Holley 360@6000 380@4000 11.0
402 4bbl Roch 350@5200 415@3400 10.25
402 4bbl Holley 375@5600 415@3600 11.0
1971
Disp Carb HP Torque C/R
307 2bbl Roch 200@4600 300@2400 8.5
350 2bbl Roch 245@4800 350@2800 8.5
350 4bbl Roch 270@4800 360@3200 8.5
350 4bbl Holley 330@5600 360@4000 9.0
402 4bbl Roch 300@4800 400@3200 8.5
1972
Disp Carb HP Torque C/R
307 2bbl Roch 200@4600 230@2400 8.5
350 2bbl Roch 165@4000 280@2400 8.5
350 4bbl Roch 200@4400 300@2800 8.5
350 4bbl Roch 255@5600 280@4000 9.0
402 4bbl Roch 240@4400 345@3200 8.5
1973
Disp Carb HP Torque C/R
307 2bbl Roch 115@4000 205@2000 8.5
350 2bbl Roch 145@4000 255@2400 8.5
350 4bbl Roch 175@4000 270@2400 8.5
350 4bbl Roch 245@5200 280@4000 9.0
1974
Disp Carb HP Torque C/R
350 2bbl Roch 145@3600 250@2200 8.5
350 4bbl Roch 160@3800 245@2400 8.5
350 4bbl Roch 185@4000 270@2600 8.5
350 4bbl Roch 245@5200 280@4000 9.0
1975
Disp Carb HP Torque C/R
350 2bbl Roch 145@3600 250@2200 8.5
350 4bbl Roch 155@3800 245@2400 8.5
1976
Disp Carb HP Torque C/R
305 2bbl Roch 140@3800 245@2000 8.5
350 2bbl Roch 145@3800 250@2200 8.5
350 4bbl Roch 165@3800 260@2400 8.5
1977
Disp Carb HP Torque C/R
305 2bbl Roch 145@3800 245@2400 8.5
350 4bbl Roch 165@3800 260@2400 8.5
1978
Disp Carb HP Torque C/R
305 2bbl Roch 140@3800 240@2000 8.5
350 4bbl Roch 170@3800 270@2400 8.5
1979
Disp Carb HP Torque C/R
305 2bbl Roch 130@3200 245@2000 8.4
350 4bbl Roch 170@3800 270@2400 8.2
1980
Disp Carb HP Torque C/R
267 2bbl Roch 125@3800 215@2400 8.3
305 4bbl Roch 155@3800 260@2800 8.6
350 4bbl Roch 170@3800 270@2400 8.2
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How can I improve performance?
On the Camaro smallblock, these are suggestions for a
mild 300hp 350cui engine with good mileage, intended for daily use.
A good 4bbl
carburetor is essential. A Q-jet can be
reworked for high performance use, or a Holley carb can be used (see later Q in
this FAQ). The stock intake manifold is adequate, but a good aluminum manifold
will improve performance further. Some examples of good aftermarket manifolds
are Edelbrock performer, Weiand action plus and Offenhauser 360. On a late
(after 73-74) engine, early cylinder heads will improve performance. A 8.5:1
Compression engine with 76cc heads will get a compression ratio of approx 9.5:1
if earlier 69cc heads are used. 69cc heads can be found on many late 60s and
'70-'71 engines.
Use a good dual pattern cam (see separate Q later in
this FAQ). Use common 4-1 headers with 1 5/8 primaries. True dual exhaust with
two separate mufflers will definitely improve performance. 2.5 inch pipes are
preferred.
Many cars came with tall (low numerical) gears.
Changing to a higher numerical gear will improve performance but give higher
cruise RPM.
Here is a chart for different rear gears for a car
with stock diameter (26.5 inches) tires:
Ratio Rpm @ 60mph
----- -----------
2.41 1900
2.56 2020
2.73 2150
3.08 2430
3.23 2550
3.42 2700
3.55 2800
3.73 2950
4.11 3250
A non lockup automatic transmission will add
100-250 rpm due to torque converter slippage.
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How can I improve my
High Energy Ignition (HEI)?
HEI (a.k.a. 'large cap' distributor) replaced the
older points style distributor (a.k.a. 'small cap' distributor) in 1974. Here
are some things you might want to try:
-
Disassemble the thing and really clean it. There's
usually quite a bit of dirt in it that makes the advance weights stick.
-
Fill the grease well! Most people don't know about
this well that's inside the distributor, and when it gets empty, the shaft
bearings and the shaft itself disintegrate.
-
Install a custom advance kit. Aim to have all the
advance in at 2600 to to 3000 RPM range.
-
Install a better than stock coil, such as the
Accel HEI coil.
-
Use good wires.
-
If you have problems with pinging, install an
adjustable vacuum advance.
-
For engines revving over 5500 RPM, also use a
hi-performance module.
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How do I grease the
HEI as mentioned above?
Do the following steps:
-
Remove the distributor from the engine.
-
Remove the cap.
-
Punch out the drive gear locking pin.
-
Pull out the shaft, complete with the advance
weights and rotor.
-
Remove the 3 hex bolts that hold the segment ring
to the housing.
-
Remove the small induction coil beneath the
segment ring.
-
You should see a plastic cover. Pry it out and you
will have reached the grease well.
-
Fill the well with moly grease.
-
When reassembling it, put moly grease on the
distributor shaft before installing it.
On early HEIs, the advance weights are mounted on
pins without nylon bushings. This direct metal to metal contact wears out the
pins and advance weight holes. The fix is to get a new set of weights (good
time to get that advance curve kit). This leaves the worn out pins and the
distributor shaft. Most books this subject say to replace the entire shaft. You
can also use a MIG welder and put a small spot weld on the worn portion of the
pin, which is then filed down to the proper shape. Also, most advance curve
kits contain the later style nylon sleeves.
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How can I keep my
headers from burning the spark plug wires?
Moroso and Mr. Gasket make loom kits that route the
wires across the top of the valve covers and then drop a pair of plug wires
almost straight down between the header tubes. But they only work if you have
90 degree boots on straight plug heads (some angle plug heads have spark plug
clearance problems). If you keep the slack in the plug wires to a minimum, the
plug wires survive just fine. These kits are especially nice if you have A/C as
they allow a fairly tight clearance to the head. You should also use the
thickest wires you can find, and a little heat wrap won't hurt either.
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What camshaft should
I get?
The two most important properties of a camshaft is
duration and lift. More duration means the power peak will move up in the RPM
band. there will be more HP, but you will have to rev more to get it. Also, low
end torque will be less so the car will soon feel sluggish, especially if it's
an automatic.
Increased lift will increase torque, but will also
make the torque curve peakier.
Two common cam profiles for the Chevy 350:
Adv Duration 262/272 (int/exh)
Duration @.050 204/214 (int/exh)
Lift .420/.442 (int/exh)
Centerline 112
This cam will give excellent result on a stock or
mild engine. Low numerical rear gears will work, stock cylinder heads are OK,
stock automatic tranny with stock torque converter etc. A 4bbl carb if
preferred. Headers and dual exhaust optional.
Adv Duration 272/282 (int/exh)
Duration @.050 214/224 (int/exh)
Lift .442/.465 (int/exh)
Centerline 112
This is a more aggressive profile. recommended is
9.0:0 C/R or higher, 4bbl carb, headers, dual exhaust. The cam will work with
a stock converter and less than 3.00 rear gears, but a 12" converter and
greater than 3.00 gears are recommended.
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What's involved in
installing/rebuilding a Quadrajet?
First start out with Doug Roe's book on Rochester
carbs. It's got good advice and plenty of pictures on assembling and
disassembling which should reviewed if you've never disassembled one. You might
even want to take some pictures or video or make some sketches before starting
to know how to put everything back together. Also make notes while you work.
Take the carb apart and reassemble it at least once without using the Quadrajet
kit so you can get comfortable with it.
You'll need to measure the float level. First, make
sure you remove all of the air horn screws including the two centers and remove
the air horn. Then holding the carb from the top, use your index finger to hold
the D-clip in place. Pick the carb up and invert it with your finger keeping
the D-clip in place while gravity causes the float to fall and pivot about the
D-clip. When the end of the float arm either contacts the rotary valve (Tomco
kits) or the viton-tipped needle seats itself (make sure the needle is
correctly clipped to the float arm), the float will stop falling. Measure the
vertical distance between the end of the top of the float and the bowl casting.
This is easier to do than pressing down on the D-clip with one finger, and
using another finger to press on the float arm to raise the float, and using
your other hand to measure the float level. When measuring, don't try to use a
tape measure or regular ruler. Get some "carb feet" instead.
The secondary air valve tension screw is not threaded
into the air horn, so do not try to remove it. Also, don't worry about removing
the choke plate or secondary air valve plates unless you absolutely have to.
The screws that hold them in are wider on the leading end. If you try to remove
them without filing that end down, you may break them off.
While it's disassembled, it's a good idea to give the
parts a good cleaning to remove the varnish and other deposits left by the
gasoline. Pick up some industrial strength carb cleaner
preferably in a gallon
can as the smaller cans are usually too small to dip the parts in. Don't use
the cleaner on any of the rubber or plastic parts or any of the vacuum
diaphragms as it will destroy them. Also remove the seal on the choke shaft
before you clean the body (don't use cleaner on it either). Clean those parts
with a soft brush. You can also let the metal parts sit in lacquer thinner
overnight to get them clean. Make sure you wear eye protection with any
cleaner.
When you do get everything clean, blow out all your
passages with compressed air to ensure they are are clean. Make sure you do
this outdoors with eye protection as you'll be blowing caustic cleaning
chemicals and small bits of metal and dirt everywhere.
Be careful placing the top back over the bowl so that
the secondary metering rods go in. During disassembly be sure to get all the
screws and covers out of the bottom of the bowl and any little ball bearing
valves out of the holes they cover.
Don't forget to remove the accelerator pump lever by
using a small diameter punch to push the split pin back toward the air horn.
Punch the pin back just enough to clear the lever. Put something like a hacksaw
blade or the blade of a small screwdriver between the pin and the horn so the
pin doesn't go all the way back. Otherwise, you'll have some big
problems trying to push the pin back into place when it's time to reinstall the
lever.
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How can I decode the
Quadrajet carbs?
Look for a number starting with a '70' or a '170',
followed by 5 other digits (wwxyz) where 'ww' is:
-
25 - 29 = 1965 - 1969
-
35 - 39 = 1965 - 1969 (with CA emissions)
-
40 - 49 = 1970 - 1979 (series 70)
-
50 - 59 = 1970 - 1979 (series 170, introduced
1976)
'x' is:
-
2 = 49-state
-
5 = CA emissions
'y' is:
'z' is:
Note that service replacement carbs don't always
apply to the above rules. In those cases, you need specific Rochester manuals.
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How do I select the
right aftermarket carb?
Here are some guidelines for the most common
aftermarket carb - the Holley 4150 and 4160.
The capacity for the carb is specified in CFM, Cubic
Feet per Minute:
Stock or mild
engine less than 1hp/cui
--------------------------------
Chevy 305 600 cfm
Chevy 350 600 - 650 cfm
Chevy 396 650 - 750 cfm
Pontiac ??????
For street use, vacuum operated
secondary are
recommended.
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What is the advantage
of a 2-piece timing chain cover?
A 2-piece cover lets you make timing and cam changes
without disturbing the front seal. The back part has the seal lip built in and
it goes on first. The front part goes on and it covers the timing set and can
be removed and installed without affecting the front seal. That means you don't
have to screw around with the oil pan.
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When was the last
year for the big-block?
For the Camaro, the 396 big block was available until
and including 1972. The Firebird had the 455 until and including 1976. There
were multiple versions available with widely varying
horsepower ratings. The
Super Duty (SD-455) version was only available in 1973 and 1974 in the Formula
and the Trans Am. The 1974 SD had a rating of 290hp and 395 lbs/ft of torque
(believed to be quite conservative for EPA purposes). In 1975 and 1976, a more
run of the mill version of the 455 was offered with a measly 200hp. Compression
during those two years was a power sapping 7.6 to 1. Since Pontiac used the
same block for all their engines (except the 301), they're not really
considered big or small blocks.
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Were there "big
block" and "small block" Pontiac engines?
No. The real Pontiac engines (326-455) differed in
bore and stroke, but had the same exterior dimensions. The 326, 350, 389, &
400 were "small journal" engines with a 3.00" main bearing journal diameter
while the 421, 428, and 455 were "big journal" engines with a 3.25" main
bearing journal diameter. The sure way to tell which one a car has is by
looking at the raised numbers on the right, front of the engine which show the
cubic inch measurement.
All heads from these engines can be interchanged. The
only thing to be careful of, is the use of high-lift cams or large-ratio
rockers. Be sure to check for valve-piston and valve-sidewall clearance. You
might have to notch the top of the cylinder wall for clearance. Compression
ratio can be modified by swapping heads since they're all compatible.
The '77 & later thin wall casting 265 and 301
V8's are known as "low deck" blocks. They are similar in appearance to the
326-455 motors except for the flat, scrawny 4 runnered intake manifold and
lower surrounding block area. The 301's weight is comparable to the Buick 231
V6.
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What years was the
Pontiac 455 available?
Although some sources say the 455 was available in
1970, it officially made its debut in 1971. Pontiac was keeping up with the
Joneses as everybody else was running 450+ cubes, so they had to. The only
problem was the early 455 was a relatively tame engine. Although it had 500
ft-lbs of torque at 2700 RPM and 360 HP at 4300 RPM (gross ratings), these revs
were much too low for real performance. All the real performance remained in
the form of the Ram Air III and IV 400 ci engines. They had power and they
revved. The 455's 1/4 mile times were in the low to mid 15s at 95 MPH, while
the Ram Air 400's were pulling low to mid 14 second times at 100 MPH. But for
the non- racer-types, it was a deal. An H.O. version was also available on the
Trans Am with some performance gains over the standard 455. It wasn't until
1973 when the 455 SD (Super Duty) came around (see details below) where the 455
really shined. The 455 remained through 1976, however like the early ones,
after 1974, they were low on performance again due to the various economical
(the energy crisis and GM bean counters) and ecological (tree huggers and the
EPA) factors.
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What is the the best
cam for my Pontiac 455?
The "041" Ram Air IV cam w/ 1.5:1 rockers is widely
considered to be "THE" cam to have in a street driven Pontiac. It was the first
"computer designed" Pontiac cam in 1969, and Edelbrock validated this profile
by copying it after extensive testing for their RPM cam some 20 years later. It
has allot of low end torque and will still rip your head off in the midrange. It
has a lopey idle at 550 - 600 RPM, but still has enough vacuum for the power
brakes. And if .470 lift isn't enough, a set of 1.65 rockers will put you at
.517. Competition Cams also has a RA IV grind in the "Muscle Car Cams" section of
their catalog. This is probably the best until someone comes up with a
hydraulic roller.
The three digit numbering scheme is nothing more than
the last three digits of the actual part number. Hence the "041" really type
"T" as mentioned in the previous question. Stock, the 455 manual cars used the
068 cam and the automatic cars used the 067 cam.
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Is there a fuel
injection manifold available for my 455?
Edelbrock and Accel have multi-port fuel injection
(MPFI) systems, however the Accel must be tuned with a laptop PC. These are
quite expensive though.
Force Fuel Engineering in Florida can handle a
conversion if you send them your manifold. They recommend an open plenum
manifold, but they can do 180 degree manifolds, too.
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How was the 455
engine different from the Super Duty version?
The Super Duty engine had the following:
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How can I tell if a
Super Duty 455 engine is genuine or not?
The Super Duty (SD) 455 was offered by Pontiac in
1973 and 1974. The fifth digit/letter of the vehicle identification number is
an 'X'. A 1973 SD block is stamped on front right (passenger) side with either
'Z8' (manual) or 'X8' (automatic). The 1974 blocks are stamped with 'W8'
(manual) or 'Y8' (automatic). The heads have a casting of '16'. Be careful, the
1968 heads were also casted with a 16 but the chamber volume is 72cc (D-port)
vs. 111cc (round port) for the SD. Also, the SD 4 barrel iron intake casting
numbers are 494405 or 494419 (1973) and 495107 (1974). An aluminum version
(casting 485640) was designed, but didn't make it into production.
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What is a Ram Air V
engine?
The Tunnel Port Ram Air V engine had the potential
for unseating the top dog Chevy. Unfortunately, very few of these engines ever
reached the public. It was only briefly offered as a crate engine through
Pontiac dealers in the early 70's.
The Ram Air V could have put Pontiac into the big
time at the track. Their Special Projects Group had developed 3 versions of the
Ram Air V by 1968: a 303-cid intended for use in the SCCA Trans-Am series, a
366-cid intended for NASCAR competition, and a 400-cid for street/strip use.
Conservative corporate attitudes and small budgets killed the 303 version. The
366 version was used in some of the smaller NASCAR divisions, but never made it
to the Grand National circuit. But the 400 version would be the closest to
making it under the hoods of the GTOs and Trans Ams. Although it never became
an official option, people with some inside knowledge could have got a Ram Air
V 400 for $2000 in their 1970 1/2 Trans Am. It's believed about 200 of these
engines were sold, but many made their way into GTOs and other Pontiacs, as
well as others being delivered by crate. But corporate HQ would ultimately cave
in to safety-conscious legislators and insurance companies. Thus the Ram Air V
was deemed powerful for street use and soon disappeared. The Ram Air 400 was
designed with tunnel port heads, manifolding and a solid lifter cam. While this
engine utilizes a basic 400 Pontiac block, there are some bonus points worth
noting.
The main-bearing web areas are beefed, with four bolt
main caps and a strengthening rib down the right side similar to the 455 SD
block, also similar are strengthening ribs in the lifter gallery. A forged
steel (SAE 4615) crank was used and was cross-drilled for superior lube
qualities. The rods were a radical new design forged from SAE 4340 material and
specially braced in the beam and cap areas. They tapered from the small-end to
a point almost as wide as the big-end opening and used an aircraft-style 12
point bolt that passed through the cap and threaded directly into the rod.
For a piston choice, Pontiac went to a TRW forging,
similar in design to the one Chevrolet was using in the 302 (Z-28) Camaro. The
pop-up configuration is different however, for an approximate 11:1 compression
ratio. The forgings were of cam-ground slipper design with a tin-plated
exterior. The tin-plating can be removed, however. At the top there is a 3/32
moly-coated ring, followed by the conventional Pontiac setup.
Back then the magic word in performance was
tunnel-port as demonstrated by the killer 427 Fords, big-block Chevys and
Hemis. Pontiac's version of this design sported machined combustion chambers
free of any rough areas that might cause hot-spots and huge, tennis-ball sized
ports. The intake ports are slightly oval in shape at the head manifold area
then flow into a circular shape for a direct shot at the center-line of the
pistons. The valves are chrome-plated, hollow-stemmed, tulip-shaped affairs,
measuring 2.19 inches at the intake and 1.77 at the exhaust. They're
super-light which contributes to the revability of the engine. The pushrods
pass directly through the center of the intake ports similar to the 455 SD,
however, instead of the round tube as on the SD, the Ram Air V head employs a
wide, tapered airfoil to direct air-flow around it. Overall flow was said to be
extremely good due to the lack of low-pressure buildup under the valves.
When it came to the cam the engineers combined the
best of two worlds. They chose the timing specifications of the successful Mark
IV Ram Air cam (308 degrees intake duration, 320 degrees exhaust duration, .520
inch lift at zero lash) but added solid lifters for faultless super-high-rpm
operation. This is extremely important because of the design of the intake
manifold and the huge tunnel ports. This is a *high* rpm engine.
Pontiac put the old boggy QuadraJet to rest as far as
the Ram Air V was concerned in favor of the 800 CFM Holley. You have to come
off the line hard as the engine doesn't start to make power until 4000 rpm and
the manifold is tuned for max power from 5000 rpm and up. I have seen pictures
of two styles of cast-iron exhaust headers with the spread-port R.A. V pattern.
One design is similar to the Ram Air III D-Port manifolds and the other is a
"shorty" version with heat shields.
There were never any specific horsepower and torque
output figures available on the R.A. V or the 303 version (designed by Traco).
Speculation was 1.15 HP per cubic inch on the Mark V in the dyno room which
should work out to something like 375 to 390 advertised horsepower. Other
published claims put the 303 SCCA version up at 430 hp, the 366 NASCAR version
at 585 hp, and the 400 street version as high as 500 hp. No one knows for sure.
But while seeing such a beast with a Ram Air V was, and is now even more so, a
rare sight - it wasn't difficult to get these cars into the 12-second range
with some simple tricks and slicks.
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How did the standard
400 and T/A 400 differ from 1977 - 1979?
The standard 400 (L78) had 180 HP and 325 lb/ft
torque. But the T/A, also had the following engine options:
1977 T/A 400 (W72/L78) - 200 HP
Better power curve
Different camshaft
Higher compression ratio (96cc 6X heads down from 101cc) 8.1:1 from 7.7
Carburetor recalibration
Different spark advance curve
Low backpressure muffler
1978 T/A 400 (W72) - 220 HP and 320 lb/ft torque
Different camshaft
More aggressive spark advance curve
Windage tray
Dual resonator exhaust with single catalytic converter
1979 T/A 400 (W72) - 220 HP
1978 shelf motor - only available with 4 speed, 2485 made
The standard 400's had a decal callout, when
present, of "6.6 Litre" while the T/A 400's had a decal callout, when present,
of "T/A 6.6". The T/A 400 also had chrome valve covers.
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What are the best
techniques for building up a 400?
Recipe for a street strip Pontiac 400 that, if built properly, will
make 450+ HP with commonly available parts:
BLOCK:
Start by boring the block .060 to get max
cubes (413), hone to a #625 Sunnen finish with .003 piston clearance and
minimum deck it. Leave, or add the scallops at the intake valve side of the
bore to unshroud the valve. Make sure the main bearing saddle alignment is +
-.001 or better. A 2 bolt block is OK providing you use studs. Remove *all* the
casting flash in the lifter valley and re-tap/deburr the whole block. Don't
forget to tap the oil galleries for threaded plugs, drill an .042 hole in the
right rear plug for dist gear cooling and chamfer the oil filter block and oil
pump holes nice and big. Take your rotary file and elongate the oil return hole
in the front of the block down to the valley floor for immediate drainage to
the pan, there are others along the sides between the lifters if you feel
energetic. Do *not* scrimp and try to save money on the block! You get what you
pay for so use a competent machine shop!
When cleaning your freshly-machined block for
assembly use *hot* water and dish soap, a steel rifle-cleaning rod will work
great for the oil passages, a 12 gauge shotgun brush for the lifter galleries
and a 9mm for all others. After cleaning soak the block with WD-40, wipe the
cylinders. You will see more blackness on your *paper
towels*. Clean again with
soap and hot water using a pressure nozzle. If you have an air compressor, blow
dry the block and coat the cylinders immediately with oil.
CRANK:
Note: see the 455 instructions for info on
stroking your 400 to 468 inches. Remember that head cc choice will be
affected.
Get an early 350 crank, have it magnafluxed for
cracks, heat treated (case hardened), shot-peened and straightened. Grind it
-.010 on the mains, offset grind the rod journals .015 (more stroke). You'll
need to go .020 undersize to get the offset. Cross-drill the crank and lightly
chamfer the rod oil- holes, chamfer the main oil-holes in a tear-drop shape in
the direction of rotation, just a small chamfer will do. Micro polish it, since
it is heat- treated it will polish nicely. Run .002 clearance on the mains.
The reason for using the 350 crank is that it is
lighter and has thinner crank throws. You can also use a late 400 crank as it
is a similar casting. Avoid very late 400 cranks as they have a different
flange. The lighter crank will reduce your rotating weight and rev faster under
load. If you anticipate super-high rpm, you may want to "knife-edge" the crank
for even less weight and less resistance.
Before installing the crank, clean it just as you did
the block. They are covered with powdered metal and abrasives after
grinding.
To use this crank you must also do the following:
PISTONS:
This is an area that I will hold back on
the tricks slightly. If you *must* know more, private e-mail will do. You will
have to reduce the weight of the *forged* 400 pistons, you can machine some off
the back-side of the dome or machine or drill holes in the pin boss area from
the bottom. Another way is to use thin walled tool steel pins, they are fairly
inexpensive. Use moly filled rings *only* with the Sunnen #625 finish. Ring
end-gap is .014 top and .018 2nd.
RODS:
You *must* upgrade your rods to at least
the '73 - '74 SD or preferably Carrillo, Crower, or any other reputable racing
rod as you will be revving this thing to 7000+ rpm easily. If you use factory
rods you will have to remove most of the small-end pad to get it light enough
to balance correctly with the 350 crank. Run .002-.0025 clearance. If you can
afford it, use racing bearings. Grooved uppers on the crank. Torque rods by
stretch to +.005 to .008.
OIL PUMP:
Use a Milodon 455 H.O. pump and
tack-weld the pickup in place. I suggest removing the cover-plate phillips
srews, loctite them and use an impact- driver to re-install them.
WINDAGE TRAY:
The stock '65-'73 Pontiac 4/5
windage tray will work fine, if you can find a full-length one use it. Take a
cut-off disk and cut 2 square openings in the end troughs and 1 long slot in
the bottom-center trough of the tray. Note the position of the end-pairs of
rods above the tray, cut your square end- slots exactly below them. The two end
slots should measure about 2.5" x 2.5" and the center slot 2.5" x approx. 8".
When you make your end cuts on each slot, continue 1/4" past the side cuts.
This will allow you to bend a flange downward along both sides. You can set the
tray on the edge of something and tap the flange down with a hammer, the metal
is very soft so it bends easily. Find a piece of course perforated or expanded
metal, cut it to size and form the same radius as the tray. Tack weld the 3
pieces in between the flanges and on the ends. This modification will allow oil
escaping from the crank to be blown directly into the pan and keep oil from
splashing up onto the spinning crank. Its good for 10-15 HP.
CAM:
Call Bob Cook at Competition Cams and go
over your proposed setup with him. He is very experienced with Pontiacs and
helps many a racer with the proper cam, etc. He is *realistic* so be prepared,
he won't let you over-cam your engine, no matter how nasty you want it. His #
is 800 999-0853.
HEADS:
Any big valve, early Pontiac head will
work as long as it has 2.11" int and 1.77" exh valves and screwed-in rocker
studs. Exceptional D-port heads would be 16, 12, 13, 62 and 48. The 62's and
16's should be fairly easy to find. These heads have 72cc chambers and should
yield a 9.7-10:1 compression ratio which will allow you to run a fairly radical
cam effectively.
Heads, more than anything are an area that will
determine how much hp your engine makes. If your cores are rusty, remove the
freeze-plugs and have them acid-dipped. Start by installing new bronze guides
and hardened exhaust valve seats for use with unleaded gas. Since the seats
will have to be blended into the port, now is a good time to do some
porting.
On a street engine, do *not* fully port the heads!
You want some turbulence in the port to keep the fuel/air mixture atomized,
thus keeping your engine from loading up. The best street port-job that will
wake-up your Pontiac is simply to open up the "bowl" area under the valve and
blend back into the port-runner. Try and keep each port relatively close in
volume, don't get carried away removing material! Just blend the seat into the
bowl/runner and polish. Use some "Dykem" machinist's dye, or if not available
use spray paint around the intake ports. Install an intake gasket and snap the
plastic locators in place. Scribe a line on the head where the ports are
mis-matched and open them up with a *large-diameter* rotary file and blend
3/4"-1" into the port. Leave the gasket on during this procedure (taped down
& numbered) to ensure a perfect match.
Minimum mill the heads if necessary and do a good
multi-angle valve job. The spring umbrellas can be discarded, make sure you use
spring dampners to reduce friction and heat build-up in them. If possible find
a 1 piece intake valve for peace of mind. At present I'm not aware of anyone
making a 1 piece exhaust valve for a Pontiac.
A good valve cover to use is a late baffled cover.
You can spot them in the boneyard by the "8" dimpled spot welds on the surface.
These covers have "fingers" that channel oil onto the rocker-balls. The
next-best would be the bolt-on baffles that came on the 455 H.O. and the like.
Poly-Locks would interfere with these however, you would have to use lock-nuts
and hardened washers.
Do not use factory head gaskets, they are too thick
and will add several cc's to your chamber volume. Do use head studs if you can
afford them, especially if you are planning to run nitrous.
INTAKE MANIFOLD:
Use a torker or preferably, a
Doug Nash. I have a friend who has a couple of them and a 750 Holley with what
ever thickness carb-spacer your hood will allow. Third choice would be a
gasket-matched early stock manifold with the #7 runner opened up to relieve the
throttle bracket bolt-boss protruding into the port, with this manifold use a
Holley 750 CFM Spreadbore (see details on installing this carb in the 455
instructions).
IGNITION:
Run an MSD #8563 distributor, 6AL box
#6420, Blaster coil #8202 and Soft Touch Rev Control #8738 (or 2 Step Rev
Control #8739). Use the biggest plug- wires you can find and stock heat-range
AC plugs gapped at .035. Experiment with the plugs in each hole while the heads
are off to get the electrode pointing down toward the piston on as many as
possible (or you can mark the plugs for later installation).
Timing curves vary with each application, a general
rule is to keep it at 34-38 degrees total and don't get wild on the street
regardless of what you've read in the magazines. Getting it "all in" by 1800
rpm will only rattle and ping. Keep that figure at around 4000 rpm unless you
cut your gas with toluene or racing fuel.
HEADERS:
If you can find a decent set of 4-tube
headers that aren't a nightmare to install and maintain use them. I recommend
3-tube "Tri-Y" headers because of their ease of installation and room, they
will also make lots of torque at a very low rpm. Always use a cross-over tube
on the way back to the mufflers and slightly smaller tube at the muffler exit.
Note that some heads will require the end exhaust ports to be drilled and
tapped for header bolts.
FLYWHEEL & BALANCING:
If you run a 4-speed
use a neutral aluminum flywheel and internally balance the engine. That will
give you a softer launch without a lot of tire spin and will rev quicker. The
stock Pontiac dampner works fine. It is a waste of money to replace it. Just
make *sure* you torque it to 160 ft. lbs.
NITROUS:
It is better to build a "hot" engine and
add mild nitrous, than to build a mediocre engine and cram it with the "happy
juice" trying to make power. The result will surely be a pile of scrap iron,
empty wallet and a severely bruised ego.
These are the basics as I see it that will give you
an 11 sec car provided you have the chassis for it. If you run slicks, the
right gears (4.33-4.88) and a race-prepared TH350 and have the chassis
extremely dialed in, I would put $$$ on a 10 sec run. All this costs plenty of
$$$, but take your time and shop for prices, it will be worth it. This info is
based on my many years of building Pontiac engines.
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What are the best
techniques for building up a 455?
Recipe for a street strip Pontiac 450. The basic engine building
technique for the 455 is similar to the 400 with the basic differences being in
the head selection and rod choice. So follow the 400 instructions when
rebuilding a 455 with the exception of the following:
CRANK:
Only a 421-455 crank can be used in a 455
block due to the large 3.25" main journals. Prepare your 455 crank as described
in the 400 primer only disregard the stroking procedure. A 400 can be stroked
to 468 inches with an .060 overbore and a modified 455 crank. These finished
cranks are available from Bruce Fulper at Rock & Roll Engineering in Grand
Terrace, CA. The cranks have the mains turned down to 3.0" and the thrust
bearing surface welded and machined to 400 specs. They have proven to be very
reliable and with the decreased bearing speed of the smaller journal they are a
good choice instead of going with a 455. The only modifications to the block
are a notch in each cylinder to clear the rod bolt.
Always heat-treat a Pontiac crank, they are cast from
tough nodular iron but after grinding they are *very* soft and won't take much
abuse. Follow the 400 instructions for crank tips. There is nothing different
about preparing a 455 crank, but note that they are already crossdrilled from
the factory. Always use a grooved top main bearing.
RODS:
Good rods are a *must* in a 455, don't even
think of anything over 5200 rpm with stock, cast 5/16" rods. The good '58-'62
forged rods with good bolts are a better choice but require heat-treating to
get up to the required minimum hardness of 25 Rockwell C. These rods also had
quirky production runs. It's hard to tell what they really are, best to avoid
them unless you're sure. The '73-'74 SD rods are first choice but *very*
expensive. Last I heard they had gone up to $135 each new. A set of Carrillo,
Crower or other racing rod is recommended instead at about $900 per set. Rods
are an area you don't want to compromise, you'll always grit your teeth when
you stomp on it if you do.
HEADS:
The only difference required here is the
chamber size, keep the chamber at about 95cc minimum for the street. There
really is not that much to be gained from higher compression except that you
can run a hotter cam (which narrows the power band). 95cc will yield approx
9:2.1 compression, it makes little sense to go higher on a street engine.
Your choice is fairly limited without major mods.
Good 455 heads are the #96's with a 95cc chamber; 7K3's at 96cc; 66's at 114cc
(although this head uses pressed-in studs it is big-valve and can be milled for
compression and tapped for srew-in studs); 197 & 7F6 round port 455 H.O.'s
at 111cc.
The 1970 GTO 455 #64 head has an 87cc chamber and was
the only high compression head offered for the 455. They are a great choice if
you want a more radically cammed and curved street-engine and don't mind
cutting your gas with toluene or racing fuel.
Best choice would be the #96 head. The 7K3's do not
have a flange on the end exhaust ports for headers. The H.O. round port heads
need the end exhaust port flanges drilled and tapped for header bolts.
Prepare your 455 heads as described in the 400
instructions.
OILING:
The large crank journals on the 421-455
require a large volume of oil. Always use the proper oil pump, a 60-80 psi
high-volume unit. Milodon makes an excellent Pontiac pump at around $40 which
puts out incredible volume, even at low rpm.
A baffled pan is a good idea in any race engine but
especially in a 455. Under hard acceleration the oil will climb the back of the
pan and rush forward under deceleration. A simple and inexpensive cure is to
cut two 1.5" wide pieces of 18 gauge or thicker sheet-metal, shape and radius
the corners to fit along the back of the pan between the sides and at the front
where it rolls up and forward. At the front you must cut a few 3/8" channels
along the edge to allow oil to readily return to the sump, weld the piece
horizontally in place in the center of the rolled section to form a rearward
lip, tack-weld it between the channels also. Weld the rear baffle in the same
fashion to the back of the pan the same height as the front to form a
forward-facing lip. Pay close attention to the position of the oil pump during
this procedure to avoid interference. These simple baffles will help keep the
oil in the bottom of the pan.
INTAKE MANIFOLD & CARB:
The same manifold
setup as described in the 400 primer will work well on the 455. Since the 455
has a longer stroke it requires more air flow, thus emphasis on porting and
induction system become more crucial. An 800 CFM carb is a good street strip
choice. The Holley 6910 Spreadbore is the direct replacement for the QuadraJet,
however they are hard to find and due to low demand Holley may stop producing
this carb. The next choice would be the 6213 designed for the BB Chevys. Both
carbs have center float bowls and are dual feed.
There are several modifications needed to use the
Chevy carb on your Pontiac manifold, they are as follows:
1) You must remove the PCV nipple from the top of the
manifold, cut an allen head 1/8" pipe plug in half (a real hassle) so it sits
flush and plug the hole to clear the carb float bowl, use the nipple exiting
the front of the carb for the PCV.
2) There is a loctited plug in the vacuum manifold
nipple at the rear of the carb base which must be removed, unfortunately it is
very soft and will probably be ruined before it comes out. An easy-out will not
grab so the only alternative is to drill the plug out. Start with a small bit
making sure it is centered and work your way up. An easy way to get around
having to tap it for a Pontiac manifold is to cut a short piece of 3/8" copper
tubing, rought half of it up with some coarse sandpaper and epoxy it into the
carb nipple (do not use 5 min epoxy), slip on a short piece of 3/8" hose and
shove the proper plastic manifold into it, Pep-Boys has a good selection of
manifolds.
3) The 6213 carb is a divorced choke style, you will
have to bend a section of rod extending from the manifold stove to the choke
linkage. I have scavenged many rods from junkyard cars, they are soft and are
easily bent to shape, after cutting to size take a pair of dykes and rotate
them around the end of the rod, that will give you a groove for the retainer
clip.
4) The stock Firebird throttle cable is 1" too short,
you can either buy a Camaro cable or use an extension. A reliable extension is
an old Ford-type threaded-rod linkage end with a ball stud in it (available at
Pep-Boys). Cut a vertical slot in the threaded end wide enough that the flat
cable end will slide freely between, drill a hole from the side and tap it.
Insert the cable and after locating the screw, insert it through the
cable-eye. You may have to tweak your throttle-cable bracket some to align
everything, an early bracket works best, they are higher and give a better
angle for the return spring. You will need a stout spring on the linkage
otherwise.
5) Your Q-Jet air cleaner will not fit the Holley, a
Chevy or aftermarket cleaner will have to be used instead.
The Holley carb will absolutely wake up your Pontiac!
They respond instantly and are dialed in easily.
CAM:
Refer to the info provided in the 400
instructions on cams, however remember that the 455 is a mid-range monster.
When selecting your cam, unless you have made major racing modifications to the
short-block keep your RPM ceiling at 6000 when selecting cam duration.
REAR END GEARS:
It makes little sense with the
torque of the 455 to use 4.xx gears, best 1/4 mile times would be with gears in
the 3.42-3.90 range.
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