The timing on my 88 TA 305 TPI has been jumping around about 2-3 deg at idle, and advances to 12 deg at 3000. I replaced the cam a month ago. I didn't replace the dist. gear. The cam has a retainer plate to hold the cam back, but there was still too much endplay ( about 1/8" or so). The guy at Comp cams Helpline said don't worry about it, so I didn't and now I have this timing problem. I'm assuming at idle the cam moves forward and back in the block, causing the erratic timing. Does this sound right? Is there any way to shim the cam where it meets the retainer plate? Or should I/ can I use a cam button? It seems odd to have to use 2 types of cam retension, or is this play normal?
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

 

Is this with the tan/black wire disconnected?
If so, did you replace the timing chain too?

 

Madmax, Yes, I did replace the timing chain & sprockets With the stock silent type, and it was with the tan/black wire disconnected- the one by the firewall on the pass. side.

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

 

Anyone else?

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

 

Jeff,

I just ant to bump the post up...I'm real interested in this 1/8th inch endplay. There's gotta be someone who's recently rebuilt a roller engine who know's.

I looked through my Helms, but didn't see any mention of endplay for the cam...strange.

 

I dont think theres supposed to be anywhere near that much play. I'd check it, but I dont have a timing gear to check it with.

I dont see a problem with using a properly installed cam button. When you looked at the retainer plate, was it flat on both sides? Its supposed to be.

 

Mike, I can't find any info on roller cam endplay in Helms, or any other SBC tech books I have. Everything seems to be on the ever-popular flat-tappet cams. Crane cams' website has an online instruction manual that states roller cam endplay as .008" or something like that. Whatever it is, it's a far cry from my .125"!
I think I'll try going to a machine shop to get a shim made to go between the cam retainer plate and the cam. I think I'd be more comfortable measuring endplay with the timing cover off, rather than a cam button, and sticking a screwdriver through the dist. hole and 'guessing'.
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock

 

Madmax, yes the retainer plate was perfectly flat on both sides. If I did go with the cam button, can I use the stock timing cover, and how long should the cam button be? Should I go with a ' roller' cam button, or would a nylon or regular steel one do?
Thanks,
Jeff

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88 Trans Am 305 Auto Red/Silver, MSD coil,wires, ported plenum, gutted airbox, TB bypass, comp cams 08-408-8, everything else stock