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Pontiac Repair/Camshaft Install


I am working on a Pontiac Super Duty 4 engine (similar to the Iron Duke 151 Cu in engine)

How much movement, if any, should there be on the cam when pulling/pushing on it in and out of the block?   Cam is held from coming out of the block by the thrust plate.  Cam is prevented from moving into the block by the cam Gear.  Should there be any movement here?  I am thinking the answer is No, How is this movement limited?   Currently I have at least 3/16 inch of movement.

I am currently using the cam spacer that was removed from the engine. (new cam and new gear are being installed)  This spacer and thrust plate is of a different design thant the stock duke engine.

This spacer is very thin, perhaps .040 thick.  It rides between the big part of the cam and the thrust plate.

The stock spacer is much thicker but it fits INSIDE the hole in the thrust plate.   It is about the same thickness as the thrust plate, so this will not provide any additional spacing.

Seems like I should have a really thick (3/16) spacer that goes between cam and the thrust plate, effectively pushing the cam fruther inside the block, and taking up this 'slack' I have now.

I have the Factory Service manual, but only mentions replacement of the spacer/thrust plate if the tolerance of .005 is exceed.   Since I have so much more movement than that, and my parts are NOT excessively worn, there must be something else I am missing.

Please help. Happy to email a picture or two if that would help.

Hi Jim:

I have not touched a tech $ engine in 20+ years literally! my online service manual stuff only goes back to 1998. if memory serves me right that 2 piece thrust washer is just to keep the cam from walking out of the block and to make sure the cam and crank gear are aligned. the dummy distributor gear at the other end is also in play on this it's a short stub shaft that is there in place of a distributor when they when to electronic ignition it drives the oil pump off the cam shaft if that gear is work out of the cam that will add to the end play you have 3/16" is a LOT of end play My guess is that gear on the oil pump drive is worn out or the gear machined into the cam chances are it's the gear on the drive more then the cam shaft. good luck :-)

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Todd Puccio


General auto repair,electrical issues,driveability issues,anti-lock brakes,SIR systems,HVAC,engine performance,Gm specific. I have worked at my current dealership since the 1990 model year anything much older than that I have limited exposure to. I do not have very much transmission experience so those question you may want to ask of another expert. When you send me a question let me know the exact make/model/engine and year for the car or suv you have it makes it easier to answer the questions that way. If your happy with the answer I gave you please feel free to Donate. This is a free service to you and I am not compensated at all by this web site. I have 22 years of experience to share with you and my knowledge wasn't free to me. I had to pay for my education.


Experience in the area: I have been a technician in GM dealerships for over 22 years and I am a ASE master technician. I work at a Buick and GMC truck store Previously I worked at a Pontiac GMC store for 18 years. I Served a a lead technician when dealership was on a team system. I just recently moved to a Buick,Hummer,Saab Store when my franchise was purchased by this dealership. Organizations: ASE master technician


Education/Credentials:High school diploma,2 year vocational school degree 2 year college degree. Associates degree in applied sciences (auto technology)Awards and Honors: GMC master technician

Awards and Honors
Master GMC truck technician Master ASE technician in 9 categories

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