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The following technical bulletins were published by AERA.


                 Cylinder Head Specifications On
                         GM 1.6L Engines

General Motors suggests the following specifications be observed
when remanufacturing the cylinder head on 1.6L engines used in
Pontiac LeMans automobiles.

Measure the cylinder head height from the deck surface to the
rocker cover rail.  The overall height should measure no less
than 3.770 (95.7mm).  GM does not recommend the reuse of heads
that fall below this minimum specification.

The installed valve stem height should be measured using tool
#J25289.  The tool straddles the valve and stem height is
measured from the tip of the valve stem to the tool.  A minimum
clearance of .015 is recommended.   The valve tip should never
extend beyond the gauge.

AERA machine shops have determined the actual installed valve
stem height to be 1.500 for the intake and 1.625 for the
exhaust valve when measured from the valve spring seat to the tip
of the valve.

                                     The AERA Technical Committee

January 1991 - TB 727



                                           Factory Undersize Crankshaft
                                                Identification Marks On
                        GM (Pontiac) 5.0 & 5.7L (305 & 350 CID) Engines

GM (Pontiac Motor Division) announced that it has changed its method identifying crankshafts with undersize main journals from their factories for 5.0 & 5.7L (305 & 350 CID) engines. 

Previously when crankshafts were used with undersize main journals, all journals were .009 undersize and 009 was stamped on the oil pan rail and the back side of the main bearings. 

Now crankshafts with only one or more (but not all) undersize main bearings will have a 9 stamped on one side of the undersize journal and a large spot of light green paint. The main bearing cap will also be painted light green on each side.

Main bearing inserts will still be identified with 009 US on the back surface.

Note: TB 172, April, 1978, provides similar information from Chevrolet Motor Division.
                                                                         The AERA Technical Committee


                              Undersize Crankshaft Diameter Caution On
                              Some 1975-76 GM (Pontiac) 3.8, 5.7 & 6.6L
                                          (231, 350 & 400 CID) Engines

Some 1975 & 76 - 3.8, 5.7 & 6.6L (231, 350 & 400 CID) engines may be equipped with crankshafts with rod journals which are .010 smaller than standard.
These crankshafts are identified by a daub of orange die on the counterweights next to the rod pin. In all cases, all rod journals will be the same undersize. If one rod journal is .010 undersize, all others will be the same. Rod bearings will also be marked with the smaller dimension.

This condition affects rod bearing journals only. Main bearing journals will be standard size.

                                                                             The AERA Technical Committee


                                             Elimination Of End Bolts &
                                       Locks From Exhaust Manifolds On
                                 GM (Pontiac) Engines Except Super Duty

All GM (Pontiac) engines after serial number 191552, except the super duty engine, will have the front and rear end bolts and locks omitted from both right and left side exhaust manifolds. 

The drilled holes in the exhaust manifolds have not been removed, and the cylinder heads will still have drilled and tapped holes. These end bolts and locks have been removed to improve the durability of the exhaust manifolds.

Caution: Do not install bolts or locks in these end holes.

                                                                                 The AERA Technical Committee


                     Revised Main Bearing Bolt On
                     1988-93 GM 1.6L VIN 6 Engines

AERA members have reported revised main bearing bolts on 1988-93 GM
1.6L VIN 6 engines. The service manual for this Pontiac Lemans
engine indicates the use of a torque to yield main bearing bolt and
also recommends using new bolts anytime they are removed.

Recently, obtaining those new bolts revealed a difference in design
which indicated they were not a torque to yield bolt. The original
design bolt has a shank-down portion and was easily identified. The
replacement bolt, Part #11503649, has been revised and is no longer
a torque to yield bolt. This revised bolt is a straight shank bolt
and no longer requires replacement, unless it is damaged or

The torque value for the straight shank bolt is also revised, it
should be 44-46 ft. lbs. The torque to yield bolt has a torque value
of 44-46 ft. lbs. plus an additional 90^ turn.

                                         The AERA Technical Committee

November 1996 - TB 1395



                        Connecting Rod Oil Squirt Holes Eliminated On       
                                      Most 1973 GM Pontiac Engines 

The connecting rod oil squirt holes were eliminated in all GM Pontiac V-8 engines on September 18, 1972, starting with engine number 106178.  Some engines prior to this date and engine number had connecting rods both with and without squirt holes.  Replacement rods may be of either type and may be used interchangeably. 
                                                                                The AERA Technical Committee


                                        Rear Main Rope Seal Alternative

The AERA Technical committee supplies the following information on a rear main rope seal alternative. The information provided below was collected over many years. This information is feedback from people like you. People tell us these seals have worked fine for them but will they work for you? AERA expresses no guarantee that they will work 100% of the time but the seals listed below have proven to be the most successful. 

During installation, offset or rotate each seal half ? to 3/8 from the main cap parting line. Place dab of anaerobic gel on the ends of the seals that will butt together. Lubricate the seal lip with straight 50 W oil or a bearing assembly lube as those lubes that will stay in place until the engine is started. Seal manufacturers do not recommend white grease alone, because they have seen too many failures from dry startups. This is especially true in rebuilt engines that sit on the shelf for long periods of time before being put into service. This is why you may have seen chunks torn out of the contact face of the seals that have 
leaked. If you have ever seen a Ford 390 or 460 tear the whole lip off the seal, it happened because it was dry started and stuck to the crankshaft.

Engine to       Detroit   Enginetech     FM            ROL             Victor            Actual
Be repaired                                                                                                  Application

Buick 231      17200      S-1389      BS-40613     RS-29470    JV-742-V     Jeep 225
Buick 350      17043       N/A          BS-40032    RS-29130      JV-618      Ford 460
Buick 455      17042        N/A         BS-30135     RS-29050    JV-730       Ford 200
GM 265/283   17053      S-0629     BS-13241     RS-29005    JV-728       Chev 250*
Caddy 365     17032      S-1196     BS-40245     RS-29040    JV-606       Dodge 318
Ford 312        17032      S-1196     BS-40245     RS-29040     JV-606      Dodge 318
Olds 260 307
330 350 403   17175       N/A          BS-6141      RS 29310        N/A         Ford 292
Olds 350D 
400 425 455   17043       N/A          BS-40032    RS-29130      JV-618     Ford 460
Pontiac 301   17091       N/A          BS-40048        N/A            JV-616     GMC 637
Pontiac 350   17043       N/A          BS-40032    RS-29130      JV-618     Ford 460
Pontiac 455   17008       N/A          BS-40012    RS-29115      JV-600     Caddy 500

* Install a .090 (2.290 mm) diameter wire in the groove, behind the seal.

It has also been reported that replacing the timing case rope seal with a National seal Part #450446 has proven effective on 455 Buick engines.                                                                                                                           On engines which use rope anti-rotation holes in the block and cap, fill them with RTV and let dry over night. 

                                                                             The AERA Technical Committee


                                        Piston Scuffing And Pin Wear On
                                             GM 2.5L (151 CID) Engines

Scuffing of piston skirts and excessive piston pin wear are common complaints with General Motors' 2.5L (151 CID) four cylinder engines.  Piston pin wear seems to be restricted to OE pistons while the piston scuffing occurred with both OE and aftermarket pistons.

General Motors uses a torque plate during production of these engines and General Motors (Pontiac) engineers recommend using a torque plate to bore and hone these engines.  AERA field reports indicate cylinder distortion exceeding .002 when torque plates have been removed from blocks after boring and honing.  The two center cylinders are affected the most.

GM has changed the design of this piston a number of times, as well as the type of material used, in efforts to solve a variety of problems.  Some aftermarket piston suppliers have followed OE designs while others have not.

Because of the variety of piston designs and differences in materials it becomes extremely important for AERA members to carefully check their piston suppliers's recommendations for fitting these pistons.  You must mic the pistons at the point specified by the manufacturer and fit to that manufacturer's
recommended clearances.  Using one manufacturer's clearances with
another manufacturer's piston could create problems on this engine.

Piston noise appears to be a bigger complaint than scuffing of piston skirts.  This could be due to excessive clearances from not following the piston manufacturer's recommendations.  AERA members report decreased customer piston noise complaints when using a torque plate to bore and hone these engines and following the minimum recommended clearances.

Some piston suppliers feel that the pin wear problem is a design problem in how the pin gets its oil supply.  Most of the OE pistons oil the pin with oil scrapped from the cylinder walls. If the engine is not properly maintained, contaminants such as carbon deposits and aluminum from top ring poundout can find their way to the pin where they will accelerate wear.  Laboratory
analysis has upheld this view in some cases.

                                                                         The AERA Technical Committee


                  Timing Gear Noise Or Knock On
            General Motors (Pontiac) 2.5L 1-4 Engines

The following information lists characteristics of timing gear
noise to assist diagnosis of problem cases involving the subject

Loose or improperly seated camshaft timing gears are usually
loudest when warm.  They are sensitive to speed only, not load
sensitive.  Cam gear noise will be noticed at a warm idle and
sounds much like a loose timing chain noise.  It is recommended
to remove the drive belts and use a sounding device on the timing
pointer.  This will provide a definite indication of timing gear

Timing gear noise is most noticeable at about 800 rpm.  It can be
heard the loudest at the timing gear cover and at the oil pan
between #3 and #4 cylinders.

If the noise has been diagnosed as timing gear related, Pontiac
Motor Division recommends AERA members use the following
procedure for checking timing gear backlash:

     1.  Remove the rocker arm cover and loosen all rocker arm
     retaining nuts on pre-1981 vehicles and shouldered bolts on
     1981 and later models.

     2.  Remove the timing gear cover.

     3.  Check the camshaft end clearance to determine if the
     gear is fully seated.  End clearance should be .0015 to

     4.  Using a magnetic dial indicator positioned on the front
     face of the engine block, place it on one tooth of the
     camshaft gear.  Be certain that the crank gear hub is

     5.  Rotate the camshaft gear back and forth.  Camshaft gear
     backlash should not be less than or exceed .0005 to .0095.

     6.  If the camshaft end clearance is over .005 or gear
     backlash exceeds .010 over the above limits, the timing
     gear and/or thrust plate should be replaced.

                                     The AERA Technical Committee

September 1983 - SB 105 



                                                  Knocking Noise On
                              1983 General Motors (Pontiac) 6000 Vehicles
                                     With 2.5L L-4 And 2.8L V-6 Engines

Pontiac reports that some 1983 model 6000 vehicles may exhibit a knocking noise from under the hood which could be caused by loose torque converter to flywheel bolts.

Loose torque converter bolts sound very much like a bearing knock and will give several raps on a quick acceleration (engine running free).  With the vehicle's transmission in gear, the noise may or may not appear at idle depending on the idle smoothness.

Before attempting to repair any bearing-type knock, check the torque converter to flywheel bolts.

                                                                         The AERA Technical Committee

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