Pontiac V8 engine

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by: Cobalt327
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Pont twin turbo eng.jpg

Warning Warning: Be sure to verify all Pontiac info found on the internet, in print, or by word of mouth. There is a lot of erroneous and misleading info out there- even from so-called experts, pros and gurus. Remember: Trust but verify!


[edit] Overview

The Pontiac engine has long been recognized as being a good engine for making a lot of torque at a relatively low RPM. Recent advances in aftermarket parts in general and cylinder heads in particular have given new life to this venerable platform. While turning your Pontiac 400 into a fire-breathing BBC eating machine can be accomplished given enough dedication and money, the Pontiac engine remains a viable economical option for building a lot of torque using basically stock castings, including blocks, heads and cranks.

As for the current (ca. 2000-up) aftermarket support given to the Pontiac engine, suffice to say that a Pontiac engine- much like a BB or SB Chevy- can be assembled using basically NO factory production parts whatsoever. Never before has the Pontiac engine enjoyed such aftermarket support, and it can truly be said that the golden years for building a Pontiac is... NOW!

[edit] Pontiac engine history

[edit] Pontiac engines by year

YEAR CID BORE (in.) STROKE (in.) MAIN (in.) ROD (in.)
1955 287 3.750 3.25 2.50 2.25
1956 316 3.9375 3.25 2.50 2.25
1957 347 3.9375 3.5625 2.623 2.25
1958 370 4.0625 3.5625 2.623 2.25
1959-'66 389 4.0625 3.75 3.00 2.25
1961-'66 421 4.09375 4.00 3.25 2.25
1963-'67 326* 3.71875 3.75 3.00 2.25
1967-'69 428 4.120 4.00 3.25 2.25
1967-'79 400 4.120 3.75 3.00 2.25
1968-'77 350*** 3.875 3.75 3.00 2.25
1969 303** 4.125 2.84 3.00 2.25
1970 366** 4.153 3.375 3.00 2.25
1970-'76 455 4.150 4.21 3.25 2.25
1977-'81 301 4.000 3.00 3.00 2.25
1980-'81 265 3.750 3.00 3.00 2.25

*The 1963 "326" engine had an actual displacement of 336 ci due to its 3.78" bore.
** The 303 and 366 were not productions engines.
***The 350 engine actually displaced 354 ci.

[edit] Pontiac engines by displacement



BORE (in.)

STROKE (in.)

MAIN (in.)

 ROD (in.)

265 1980-'81 3.750 3.00 3.00 2.25
287 1955 3.750 3.25 2.50 2.25
301 1977-'81 4.000 3.00 3.00 2.25
303** 1969 4.125 2.84 3.00 2.25
316 1956 3.9375 3.25 2.50 2.25
326* 1963-'67 3.71875 3.75 3.00 2.25
347 1957 3.9375 3.5625 2.623 2.25
350*** 1968-'77 3.875 3.75 3.00 2.25
366** 1970 4.153 3.375 3.00 2.25
370 1958 4.0625 3.5625 2.623 2.25
389 1959-'66 4.0625 3.75 3.00 2.25
400 1967-'79 4.120 3.75 3.00 2.25
421 1961-'66 4.09375 4.00 3.25 2.25
428 1967-'69 4.120 4.00 3.25 2.25
455 1970-'76 4.150 4.21 3.25 2.25

*The 1963 "326" engine had an actual displacement of 336 ci due to its 3.78" bore.
** The 303 and 366 were not productions engines.
***The 350 engine actually displaced 354 ci.

[edit] Engine ID

[edit] Block ID

[edit] Head ID

[edit] Other ID

[edit] Bore and stroke

CID BORE (in.) STROKE (in.) MAIN (in.) ROD (in.)
265 3.75 3.00 3.00 2.25
287 3.75 3.25 2.50 2.25
301 4.00 3.00 3.00 2.25
303** 4.125 2.840 3.00 2.25
316 3.9375 3.25 2.50 2.25
326* 3.71875 3.75 3.00 2.25
347 3.9375 3.5625 2.623 2.25
350*** 3.875 3.75 3.00 2.25
366** 4.153 3.375 3.00 2.25
370 4.0625 3.5625 2.623 2.25
389 4.0625 3.75 3.00 2.25
400 4.12 3.75 3.00 2.25
421 4.09375 4.00 3.25 2.25
428 4.12 4.00 3.25 2.25
455 4.15 4.21 3.25 2.25

*The 1963 "326" engine had an actual displacement of 336 ci due to its 3.78" bore.
** The 303 and 366 were not productions engines.
***The 350 engine actually displaced 354 ci.

[edit] Heads

Return to Parts interchangeability

[edit] 6X heads

Casting 6X heads and similar heads from the "smog era" generally all have hardened exhaust seats, screw-in rocker studs and guide plates, with 2.11" intake x 1.66" exhaust valves. See How to Identify Pontiac's Small Chambered 6X Head for more info on ID'ing 6X heads.

When inspecting 6X head and Pontiac heads in general, check the spring installed height to be sure it is equal between the valves. The spring's seat and open pressure is also important but all but impossible to measure unless the springs are checked w/a spring gauge. There are spring gauges that can be used on an assembled head. When buying assembled heads, demand a receipt showing part numbers. That will not guarantee anything but will cut down on the BS.

[edit] 4X heads

Stamped ID Application Valve Diameters Rocker Studs
1H 455 4-bbl 2.11/1.66 Pressed-in*
3H 400 4-bbl Manual 2.11/1.66 Threaded
4H 400 2-bbl 1.96/1.66 Pressed-in*
7H 400 4-bbl Auto 2.11/1.66 Both*
*All rocker arms studs are threaded beginning with unit number 709986, assembled on or about May 7, 1973

[edit] Secondary head code identifiers

[edit] 1973-'74 4X, 46, 4C, 16/X

Stamped ID Head # Chamber Volume
Valve Diameter
int./exh. (in.)
Valve Length
1H / 14X 112.302.11/1.664.78455
3H / 34X98.212.11/1.664.86400
4H / 44X98.941.96/1.664.86350/400
5H4C (AIR)96.171.96/1.664.86350
6H 4696.171.96/1.664.86350
6H16/X110.742.11/1.774.97455 SD
8H / 84C (AIR)98.941.96/1.664.86400

[edit] 1975 (early) 5C, 51

Stamped ID Head # Chamber Volume
Valve Diameter
int./exh. (in.)
Valve Length
65C / 51124.512.11/1.664.71455
75C (AIR)100.042.11/1.664.86400
95C (AIR)93.742.11/1.664.86350

[edit] 1975-'79 6X, 6H

Year Stamped ID Head # Chamber Volume
Valve Diameter
int./exh. (in.)
Valve Length
1975-'76 46X93.742.11/1.664.86350
76S (AIR)100.042.11/1.664.86400
96S (AIR)93.742.11/1.664.86350
1977 46X93.742.11/1.664.86350 / 400 W72
1978 86X100.042.11/1.664.86400
46X93.742.11/1.664.86400 W72

[edit] Valve sizes

Often, modified Pontiac "X" heads have 1.77" exhaust valves installed in place if the stock 1.66" and this is obviously going to be very easy to determine. As far as the rest of the work that may have been done to the heads, you can visually look to see if they both have at least 3-angle seats (that won't tell you if the seats are concentric, though). The valves can be inspected to see that they have adequate margins, seat widths, and if they've been back cut or have undercut stems. I would suggest measuring the valve guide clearances, too.

[edit] Combustion chamber volume

One of the most important things that need to be known about the heads is the exact chamber volumes. First, look to see that the secondary identifiers are the same. Even if they are, both heads need to be checked- although doing the end chambers of each head (four chambers total) will be enough to tell that the chambers are equal. This is necessary because there's no way to be sure the heads were always a pair from day one, onward. Even if they were paired from birth, one head might have had a bad head gasket that required it to be resurfaced. If both heads weren't cut an equal amount that can cause the chambers to vary. If the heads were from different engines originally, obviously they can vary due to all the above reasons plus manufacturing and casting differences from the factory.

The combustion chamber volume can be changed by milling the head deck. One cc will be removed per 0.005" removed from the deck. All heads can be safely milled 0.050". The 1971 #96 and the 1972 #7K3 heads can be safely cut 0.070" and the 1971-'73 round port heads can be cut 0.085". If 0.030" or more is removed, the intake side of the head should be cut equally to keep the port and bolt holes in alignment. The chamber volume should be rechecked after a valve job; most times a valve job on the same size valve (not replacing a smaller valve with a larger valve) will add 2-4cc to the chamber volume.

There were three sizes of combustion chambers on 6X heads. For most builds, the small chamber head is what is wanted. The late large chamber 455 heads on a 400 will put the compression ratio in the 7.8:1 range, even with a 0.040" quench. The small chambered 6X and similar head on a 0.030" over 455 with a 0.040" quench will result in a CR of about 9.75:1. On a 400 the CR will be around 9.2:1.

  • 6X-4 and 6X-7: 93cc (have been seen to be as much as 95cc). The 6X-4 heads were found on mid '75-'77 350ci; 1977-'79 W72 400ci (TA "6.6 Litre" option)
  • 6X-6: 124cc, these would have been on a 455
  • 6X-8 and 6X-9: 101cc
  • There are also 1973-'74 casting 4X heads that have 98cc chambers and screw-in studs, but the intake port size is about 5cc smaller.
  • The 1975 casting 5C heads have 101 cc chambers, but they supposedly have about 7cc smaller runners than the 6X heads. Bigger is better, in this case.

The 4, 6, 7, 8, and 9 identifiers can be found stamped on one of the vertical ribs on the side of the head. These heads have hardened exhaust seats, screw-in rocker studs and guideplates, 2.11" intake x 1.66" exhaust valves. They can be easily converted to 1.77" exhausts. If nitrous or high rpm is in the cards, this mod should be considered.

A compression ratio calculator can be used to calculate compression ratios when using different chamber sizes, etc.

[edit] Port volume

Then there's the port volumes. These heads have relatively small intake ports; the 6X-4 heads used on one 455 build were 158cc "stock" (these ports have also been measured at 153 cc), and they did not look to have been ported. After porting they measured 173cc. These stock sized ports would be like a ~ 125cc head on a 350 SBC. The comparison isn't as bad as it sounds because of the design of the Pontiac head/ports and the 30 degree intake valve angle, but the fact remains- they ARE small.

Usually a stock or mildly reworked D-port Pontiac head doesn't need lift in excess of 0.480". That is a little past where maximum flow is reached but before any port stall occurs, given the rpm range of a 455. Combining that w/a duration @ 0.050" of around 234-236 degrees or so will be about right for a strong street engine that will run mid 12 second ETs at the drags and can be driven daily, anywhere, without issue, on 89 octane gas, and using a 2.73 to 3.31 gear ratio is all that's needed.

[edit] "Low compression" heads

Be aware that published figures often differ. The only sure way to know what the combustion chamber volume is, is to actually measure it. This will take everything into account: previous valve jobs, milling done to the decks, manufacturing and casting tolerance creep/stack up, etc. Obviously an alternative to using the larger chamber heads is to install dished pistons and use any of the smaller chambered performance heads.

[edit] Original head applications

CastingSecondary IDValve diameter (in.)Chamber volumeOriginal application
4X1/1H2.11/1.66112 cc1973-'74 455ci 4-bbl
4X3/3H2.11/1.6698-99 cc1973-'74 400ci 4-bbl manual trans.
4X4/4H1.96/1.6698-99 cc1973-'74 400ci 2-bbl
4X7/7H2.11/1.6698-99 cc1973-'74 400ci 4-bbl auto trans.
4C5/5H1.96/1.6696 cc1973-'74 350ci 2-bbl w/A.I.R.
4C8/8H1.96/1.6698 cc1973-'74 400ci 2-bbl w/A.I.R.
466/6H*1.96/1.6696 cc1973-'74 350ci
5C42.11/1.6692-94 cc1975 350ci
5C72.11/1.6699-101 cc1975 400ci w/A.I.R.
5C82.11/1.6699-101 cc1975 400ci
5C92.11/1.6692-94 cc1975 350ci w/A.I.R.
6X42.11/1.6692-94 ccMid 1975-'77 350ci; 1977-'79 W72 400ci
6X82.11/1.6699-101 ccMid 1975-'78 400ci
6S72.11/1.6699-101 ccMid 1975-'76 400ci w/A.I.R.
6S92.11/1.6692-94 ccMid 1975-'76 350ci w/A.I.R.
5162.11/1.66124.5 cc1975 455ci
6H62.11/1.66124.5 ccLate 1975-'76 455ci
*Some reported to have a secondary stamp of "2"

[edit] Studs and guideplates

Heads having pressed in studs will usually have smaller valves than heads having screw in studs, although there are exceptions to this like the 4X-1H 455 head. Pressed stud heads have a tapped hole between the studs for attaching a guide plate on most heads.

Pressed vs screw stud pont.jpg

[edit] The bottleneck stud

Stock type Pontiac bottleneck stud
Pontiac heads like the 6X and practically all other production Pontiac heads likely to be used in a performance-orientated build originally had screw in bottleneck studs and steel guideplates. There are some exceptions to this, like heads having pressed in bottleneck studs, and the Ram Air IV and "Ram Air II" round port heads, which used a straight 7/16" stud with an adjuster nut/lock nut arrangement.

The usual stock D-port arrangement is a "net lash" set-up. Because the rocker stud is 7/16" OD at the bottom, the rocker arm and pivot ball is also made to fit a 7/16" OD stud, so the stock rocker arm and ball can be reused with a straight 7/16" stud. The top of the bottleneck stud is threaded for a 3/8-24 nut, to be torqued to 15 ft/lb to retain the rocker arm.
The stock Pontiac net lash lifter preload adjustment may be adversely affected by any of the following:

  • Block deck height change
  • Head deck height change
  • Head stud boss height change
  • Rocker arm brand/design
  • Cam base circle size
  • Lifter design/brand/pushrod seat height
  • Valve stem length
  • Head gasket thickness

So if any of the above changes are made, the stock Pontiac bottleneck stud/net lash set-up may no longer preload the lifter properly. Unless the studs are changed to allow for an adjustable valve train, different length push rods may be needed to set the lifter preload- but changing the length of the push rod can adversely affect the valve train geometry. For that reason it is advisable to use straight studs to replace the bottleneck studs. A good replacement is ARP p/n 190-4003 w/hex nuts, or p/n 190-4203 w/12-point nuts. Be aware that there can be clearance issues between the polyloc and valve cover if polylocs are used. Check the clearances carefully; you might be able to use a shorter polyloc. If possible (and the valve cover are so equipped) keep the oil drippers. The oil drippers are a separate piece from the valve covers on the RA II/IV engines.

While it is not recommended, the bottleneck studs will sometimes work as an adjustable valve train if a stock SBC lock nut is used and the camshaft is very mild. But this does nothing for the inherently weaker design of the bottleneck stud.

The stock Pontiac guideplates are fine to reuse as long as the pushrod diameter is the same as stock or if the pushrod OD is larger, the holes are tweaked to allow the pushrods to fit without interference.

[edit] Rocker arms

Most Pontiac engines came with 1.5:1 ratio rockers. Exceptions to this were the Ram Air IV engines, which used 1.65:1 rockers. The 1.65 rockers can be used on any Pontiac head but the push rod guide hole in the head has to be carefully inspected/enlongated at the top of the opening. More on rocker arm ratios, including cautions can be seen here.

[edit] Valve springs

Cliff Ruggles has said "We use and prefer the Crower p/n 68404 (1.6" installed height) or p/n 68405 (1.7" installed height) for flat hydraulic cams with Pontiac cylinder heads."

[edit] Round port heads

D-port #13 heads above a Ram Air IV head

Round port heads were long favored for high performance. But they are scarce (read expensive), and don't flow all that well, at least when compared to aftermarket heads.

But now that Edelbrock and others have come out with affordable aftermarket aluminum heads, the round port heads are all but ignored by the performance crowd. But to restorers, they are still highly sought after.

[edit] "Pete's Picks"

Pete McCarthy did a huge head air flow test that was originally written up in the April and June, 1991 editions of High Performance Pontiac, titled The Ultimate Head: Part I.

The results:
  • Best performance head: 1970 Ram Air IV
  • Best intake port: 1969-70 Ram Air V
  • Best exhaust port: 1968 1/2 Ram Air II
  • Best D-port head: No.16, No.48, No.12 (tie)
  • Best low compression D-port head: No.96(1971)
  • Best low compression post-1972 head: No. 6X
  • Best balanced head (exhaust to intake): 1963 421 SD
  • Best low-lift (under .400) head: 1967 No.670
  • Worst exhaust-to-intake port ratio: 1969-70 Ram Air V
  • Worst intake-to exhaust ratio: 1968 1/2 Ram Air II
  • Biggest surprise: Intake port, No.17 350 head
  • Biggest disappointment: 1969-70 RA V, 1973-74 455 SD (tie)
  • Biggest "sleeper": 1975 No. 5C
  • Most under-cammed: 1963 SD, 1971 455 HO, 1973-74 455 SD (tie)
  • Most under-exhausted: 1964 GTO (No.9770716)
  • Most potential for porting: 1973-74 455 SD, 1968 1/2 RA II (tie)

[edit] Cams

According to Pontiac expert Pete McCarthy, "Low-lift exhaust deficiency has been a Pontiac curse for many years. That is why all the Pontiac stock cams, with the exception of the very first profile developed (No.518111 "A"), are dual pattern, with a longer-duration exhaust lobe."

A dual pattern cam like Comp Cams' XE series or a Lunati Voodoo would be good cams to look into. For info on Comp Cams XE series of cams you can contact Butler Performance for good solid info. For info on Crower cams contact Kauffman Racing Engines or Spotts Performance. These shops can be contacted via phone or email.

Return to Parts interchangeability

[edit] Intakes

With the D-port heads, unless they've been heavily ported, an RPM intake is a good choice. It will hit harder off idle and gives up nothing to a single plane at the modest peak rpm the 455 is going to be turning (5000-5500 rpm in street trim), built as described here; harnessing the torque by using sticky drag radial tires will give the maximum all-around performance. There might be an argument made for a single plane to "tame the torque". But that might be better left until all other avenues have been exhausted.

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[edit] Heat cross over

1972 and up cylinder heads using earlier intakes can use Felpro intake gasket p/n MS90205 or Mr. Gasket p/n 5848 to seal the exhaust crossover.

Heat riser block off schematic

Exhaust Crossover Port Match Ups

** Use stainless steel sheet block-off plate

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[edit] Pistons

Generally, using flat top pistons are the best way to go. There may be cases where a dished piston is needed, but the cost is generally higher than cast flat tops.

Because the 1967 and newer valves don't line up correctly with the 1966-back piston valve reliefs in the pistons (and obviously vice-versa), the correct piston has to be used if any sort of aftermarket high lift cam is used, or else there may be destructive valve to piston interference. There are 8-valve relief pistons available to fit all the valve angle differences used through the years on Pontiac engines. While these pistons will get the job done, from a high performance standpoint they are not desirable.

Pontiac went to an advertised 7.6:1 compression in about 1975, due in part to the design of the top of the pistons. Pontiac pistons from the low compression years have a 45 degree machined outer edge of the piston top.

Note 45 degree cut (arrow) to the top edge of the low compression piston
8 valve relief rebuilder-type piston, undesirable for high performance use
Return to Parts interchangeability

[edit] Rods

There are now inexpensive, good quality Pontiac rods. Years ago all that was available were high dollar rods like Various aluminum rods, then Miller, etc. or the weak factory forged rods or weak factory cast rods. Neither the cast or forged production Pontiac rod is a good choice if the engine will see hard use or high rpm. At a bare minimum, cast rods need to be resized and ARP hardware installed, and the rpm has to be kept under 5500 rpm (455) or 5800 rpm (400).

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[edit] Cranks

The factory cranks are good. But if a crank is needed, it would be worth looking at a stroker to make a 400 into a small journal 455. Smaller main journals of the 400 make it a better foundation for building a high performance 455 than an OEM 455 block.

This info on crankshafts is from the www.pontiacpower.org site.

Warning Note: Starting around 1966-'67, not all cranks were machined for a pilot bearing, so be sure to check to see if the crank needs machining before installing the crank if a manual transmission is to be used.

Warning Note: Pre-'64 cranks are not machined for TH-type torque converter hubs. They can be machined to fit, though.

Return to Parts interchangeability

[edit] Pontiac crank numbers

Year         Engine        Material     Crank#          Notes
1939-1954    all 6cyl                   506176      
1946-1949    all 8cyl                   508454      
1950-1954    all 8cyl                   512512      
1955           287         FS           518047   
1956           317         FS           521602   
1957           347         FS           530048   
1958           370         FS           528527   
1959-1962      389         AS           531369      except Super Duty
1959-1960      389         SD,FS        533038      Limited production
1961-1962      389         SD,FS        541649      Limited production
1961-1963      421         SD,FS        542990      Limited production (approx 2000)
1961-1962      215                      542239      Tempest
1961-1963      4cyl                     1193645     Tempest
1962-1963      421         AS           9770488     And HO engines
1963           326         AS           545585      Special Tempest transaxle hub
1963           389         AS           544191      Pontiac V8 except 421
1964-1965      6 cyl                    3864465     Tempest; supplied w/o pilot brng
1964-1965      V8          AS           9773382     Tempest inc. 389 Armasteel "400"
1964-1965      389         AS           9773383      
1964-1965      421                      977384      And HO; might require different
 connecting rod for balance

1966           421         AS           9773384     1st Type: if using 1965 type
 piston, different connecting rods are required

1966-1967      326         AS           9782770   
1966           389         N            9783786   
late 1966      421         AS           9783787   
1966-1967      6 cyl                    9782279     Firebird and Tempest; use pilot
 bearing P/N 3752487 for MT

1966-1968      421-428     AS           9783787     2nd type: AS long snout
1967-1970      400         AS           97954       Except Ram Air, late 
1967-early '68 400         N            9773524    
1968-1979      400         N            4813        Both "N" crank and standard 
 w/2-3/4" flange, early

1968           350         N            9793573     Late
1968-1970      350         N            9795479     
1968           400 RA      AS           9794054     WU, WY, XT, XW engines
1968-1969      6 cyl                    9790154     Firebird and Tempest; use pilot
 bearing P/N 3752487 for MT

Late 1968-1969 428         N            9782769      
1969           303         FS           546270      Limited production
1969-1974      400         N            97954       2-3/4" flange
1969           400 RA IV   N            9795481     WH, WW, XN, XP engines, +0.001" 
1970           400 RA IV   N            9795481   
1969           400 RA V    FS           545671      Limited production
1970           366         FS                       Moldex forged, limited production
1970-1979      350/400                  9773524     Non "N" with 2-3/4" flange
1970-1976      455                      496453   
1970-1976      455         N            9799103     Approx wt. 72 lbs. came both "N"
 and standard

1971-1974      350         N            4813  
1971-1974      400         N            4813   
1972           455 SD      FS                       Kellog forged, limited production
1973-1974      455 SD      N            490164      W8, Y8, X8, Z8, ZJ, XD engines
1973-1976      455         N            496453      Service replacement
1975-early '76 350         N            496452      Thin counterweights
1975-early '76 400         N            496414      Thin counterweights
1975-1976      455         N            496415      Thin counterweights
1975-1976      455         N            496453      Thin counterweights, late
1976-1979      350         N            496452      Thin counterweights, late
1976-1979      400         N            499864      Thin counterweights
1977-1981      301         N            525887      End counterweights only
1980-1981      265         N            525887      End counterweights only 

SD: Super Duty
FSD: Forged steel
AS: Armasteel
RA: Ram Air
MT: Manual transmission

[edit] Pilot bearing

The Pontiac uses a rolling element-type pilot bearing as opposed to a bushing.

BCA p/n 7109 pilot bearing
Pilot bearing is BCA p/n 7109 (available from Summit and Ken's Speed and Machine, among others). The GM part number is 15533265. The dimensions are 1.3780" OD x 0.5906" ID x 0.3543" wide (35 mm OD x 15 mm ID x 9 mm wide). According to www.pontiacpower.org, the cheaper p/n 6202 bearing may be used, but the crank opening may need to be machined 2 mm deeper. The p/n 6202 is 35 mm OD x 15 mm ID x 11 mm wide. The 6202 is available with shields on both sides to keep dirt out.

The outside of the crank opening is staked with a chisel in at least two places to hold the bearing in place because the pilot bearing is a slip fit into crank recess.

[edit] Ignition

Pontiac firing order.jpg

Warning Note: Often a specific distributor cap terminal was designated by the factory to be "number one". And the terminal designated as #1 will often be different depending on whether the ignition is points or HEI.

But in actuality, terminal #1 can be any terminal. As long as the piston is at TDC ready to fire (not on exhaust stroke), whatever terminal the rotor is pointing to can be designated to be #1. Just be sure there is enough rotation allowed by the vacuum advance before it hits the firewall or intake to set the timing.

CCW orientation of mechanical advance weights and cam

See Hot rodding the HEI distributor.

[edit] Timing covers

The following is from High Performance Pontac forums:

All of the timing chain covers from 1964 to 1979 will bolt up and interchange with any motor from those years. However, you must use the matching water pump, pulley and crank pulley to avoid alignment problems with the alternator and/or power steering pump.

All of the water pumps from '64-'68 will interchange. These pumps have eight bolts and measure 3-5/8" long (from base to water pump pulley flange). The casting number for '64-'65 is 9772716 and for '66-'68 it is 4782482. The matching pulleys are 2" in height.

From '64-'67 Pontiac used a small diameter (5.25"), six bolt two-piece harmonic damper and from '68-'79 a large diameter (6.75"), four bolt one-piece damper was used. In '69 Pontiac changed to an 11-bolt water pump but the early '69 was different from late '69-on. Many early '69 Firebirds and GTOs used a water pump that measured 4" long (casting #9796351) and the pulley was 2-1/4" in height. From late '69 to '79 only one pump style was used, it measured 4-1/2" long and there are at least two different casting numbers used: 482138 and 488296. The matching pulley should measure 2-5/8" in height. Always use the correct diameter and style crank pulley to match the water pump pulley and also use the same series timing chain cover and balancer to properly line up your timing marks.

The same timing chain cover was used for both '64 and '65 and had just a simple pointer. These were cast with number 9773371. The timing cover used on '66 and '67 employed a small timing scale marked -4-0-+6 and is otherwise identified as casting #9783130. The '68, '69 and '70 timing covers look very similar with timing marks of 0-6-12 degrees BTDC and accommodated the large diameter damper. The '68 timing cover casting number is 9790347 and uses the 8-bolt water pump. The '69-'70 timing cover casting number is 9796346 and uses the improved 11-bolt pump. For '71-up the timing cover timing tab is marked from 4 degrees ATDC to 12 degrees BTDC and is graduated all the way to 16 degrees BTDC. As compression ratios were lowered to 8:1 and less there became a need for increased initial advance. Casting number for this cover is 482883. If you need to order a water pump the Federal Mogul part numbers are: '64-'68 is FP1388N, early '69 is FP1409N and late '69-on is FP1423.
Return to Parts interchangeability

[edit] Cooling system

[edit] Water pump

There were two basic water pump designs used between 1964 and the end of production: an 8-bolt (up to '68-early '69) and an 11-bolt pump used after the 8-bolt pump.

If the engine seems to be overheating, first be sure the temp gauge is reading correctly. Use a temporary mechanical gauge to check it. Then check the ignition timing to be sure it's not retarded.

Be sure the thermostat is working as it should. If you have a clutch fan, check it for correct operation as well. Be sure there's no belt slippage- sometimes you won't hear the belt squeal. If you have a flex fan, they can cool poorly. You also need a shroud that fits the fan assembly.

Here is some info on the divider plate that shows how to set the clearance up. No rust holes allowed!

Also be sure the sleeves/grommets are in place correctly.

Red arrow indicates rubber grommet inserted into sleeves used on 11-bolt water pump assembly

[edit] Oil filter mount

In some cases the oil pressure gauge sender will hit the top of the filter. In that case, use an angled fitting as shown below. The threads are 1/4-18 NPT.

Pont oil housng11.jpg

[edit] Parts interchangeability

Based on info from teufert.net and Ken's Speed & Machine.

Block: 1955,1956,1957,1959-'60,1961-'64 (full size V8), 1964-'69 (Tempest/Grand Prix V8), 1970-'79
Note: No block mount starter holes on pre-1964 blocks
Bellhousing: 1955, 1956-'57, 1958-'60, 1961-'64 (fullsize), 1964-'79 (all except 1964 fullsize)
Oil pump: 1955-'58, 1959-'79; all use the same oil pump shaft
Oil pan: 1955-'58, 1959-'60, 1961-'63, 1964, 1965-'71, 1972-'79
Note: Same pan can be used from 1964-on with proper rear pan seal
Windage tray: 1955-'58, 1959-'60, 1961-'62, 1963, 1964, 1965-'72
Note: #2 and #4 main cap holes are for windage tray mounting. After 1972 some blocks have no provision for windage tray mounting. Center main cap holes (#3 cap) are for lower dipstick bracket
Oil filter: 1955-'59, 1960-'79
Oil filter mount: 1955-'59, 1960-'62, 1963, 1964-'70 (straight), 1967-'79 (tilted)
Note: There are basically two different oil filter housings: Pre-1970 straight mount and the later angled housing mount. Also special adapter for a rearward facing oil filter housing to clear RA III and IV exhaust
Crankshaft: 1955-'56, 1957-'58, 1959-'66 (3" main), 1967-'78 (3" main), 1962-'76 (3.25" main).
For all engines after 1964: 326, 350, 389 and 400 use the 3" mains. 421, 428 and 455 use the 3.25" mains.
Warning More at Cranks
Harmonic balancer: 1955-'62, 1963, 1964, 1965, 1966, 1967, 1968-'79
Note: Some 1977-up 400 and 301 use a crankshaft hub without a rubber torsional ring
1955-'57, 1958-'60, 1961-'62, 1963, 1964-'79
Note: There are two different diameter flanges used on the 400 crank after 1975: 2-1/2" and 2-3/4".
All 350/389/400/428 and 455 with same flange will interchange.
Also watch the pilot ID on early pre-1964 389 Armasteel cranks when using an automatic
Warning More at Modern GM transmission behind early Pontiac engine
Connecting rods: 1955-'79
Note: Before 1962 forged rods were installed, but weaker then the later cast rod unless heat treated and prepped. Swapping to the earlier lighter forged rod requires re-balancing
Warning More at Rods
Pistons: Must match the bore, stroke, and head series
Note: 455 SD piston use SD rod unless the pin boss is internally milled.
Warning More at Pistons
Wrist pins: 1955-'57, 1958-'62, 1963-'65, 1966-'79 Some SD pins are longer
Heads: 1955, 1956-'60, 1961-'66, 1967-'79
Note: Valve centers were widened in 1967 for larger valve diameters.
Warning More at Heads
Rocker arm: 1955, 1956-'60, 1961-'64, 1963 (421 HO)-'64 (GTO Tripower), 1965, 1966, 1967 (326 only), 1967-'79
Note: Ram Air IV engines used a 1.65 ratio, the pushrod holes were factory enlarged for this.
All other heads have to be modified to use 1.65 rocker arms
Pushrods: 1955-'60, 1961-'66, 1967-'76 (except longer Ram Air IV)
Note: Match pushrod to year of head
Valve covers: 1955-'57, 1958-'60, 1961-'62, 1963-'66, 1967-'79
Lifters: 1955, 1956-'79
Camshaft: 1955-'79 (except Ram Air V/455 Super Duty).
Warning More at Cams
Intake manifold: 1955, 1956, 1957-'58, 1959-'60, 1961-'62, 1963-'64, 1965-'71, 1972-'79
Warning More at Intakes and Heat cross over
Exhaust manifolds: 1955, 1956, 1957, 1958, 1959-'79 (D-port); 1968-'74 (round port)
Note: While the manifolds physically fit the engine, the oil filter mount, steering box, and chassis configurations all need to be considered if using a non original manifold
Distributor: 1955-'79 (except Ram Air V/455 Super Duty)
Starter: 1955, 1956-'60, 1961-'64 (fullsize), 1964 (Tempest/Grand Prix)-'79
Timing Cover: 1955-'59, 1960, 1961-'62 (inc. Tempest "Trophy" 4), 1963, 1963 1/2-'65, 1966-'67, 1968, 1969-'79
The only difference in the 1968-up timing covers are the timing indicator markings.
Some late model 400 and 301 covers have a plastic bolt-on tab.
Warning More at Timing covers

[edit] Modern GM transmission behind early Pontiac engine

Due to the differences in the early crank flange and the lack of a drilled block mounted starter mount on the block, a TH 350/400, etc. tranny won't work behind an early (pre ~1964) engine. Wilcap and Bendtsen's sell kits that allows the later trannies to bolt up behind these early engines.

[edit] Original build information

Ever wondered how your Pontiac was originally equipped? A service has been established by Pontiac Historic Services, P.O. Box 884, Sterling Heights, MI, 48311-0884 to research original build information for 1989-back Pontiacs. See them on the web at www.phs-online.com. Information on your Pontiac is $65.00 ($75.00 U.S. for international orders) as of 2012.

[edit] Jim Hand tech articles

Jim Hand has been a prolific writer on the Pontiac scene for decades. The following is a few articles by him; others can be found on the web:

[edit] Also see:

7K3 heads drilled for headers. Spots Performance also sells "L" brackets for heads like these that don't have the pad.
Another view of 7K3 heads drilled for headers
1968-up open chamber Pontiac machined combustion chamber
Tri Power induction set up

[edit] Resources

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