[jpd37]

I am reassembling a 1988 GM 5.7 liter motor. I cannot find any information on the attachment of the timing gear to the cam. Does the cam require any component to prevent the cam from riding forward? It seems to me the cam gear bolts directly to the cam and there is nothing to prevent the cam from riding forward other than the timing chain. That does not seem right. Is it?

[curtis73]

If its a truck motor with a flat tappet cam, it doesn't need anything. Flat tappet cams have tapered lobes, so the force on the lifters also forces the cam toward the back of the block.

If its a car motor with a roller cam, there is supposed to be a cam button that fits in the snout of the cam. The cam button is a spacer that fits between the cam and timing cover and prevents the cam from walking forward.

[oldbogie]

Originally Posted by jpd37

I am reassembling a 1988 GM 5.7 liter motor. I cannot find any information on the attachment of the timing gear to the cam. Does the cam require any component to prevent the cam from riding forward? It seems to me the cam gear bolts directly to the cam and there is nothing to prevent the cam from riding forward other than the timing chain. That does not seem right. Is it?

If this is a flat tappet cam, Chevy expects that some cam lobe angle and your good looks will be sufficient to retain the cam. Sometimes this works and sometimes it doesn't. It doesn't often enough for GM to have suffered thru several class action law suits regarding abnormal cam wear. The fact that GM has for the most part stayed these suits doesn't mean the cam and lifter wear didn't happen, the courts just haven't attached Chevy's lack of through engineering to the resultant thousands of failures. My old 78 being among them and trust me while GM made it sound like people with cam troublels were dolts deserving of the failures by their own actions, or lack there-of, I'm an example of being on top the oil change situation with always using the right stuff.

So, and especially in this age of diminishing oil additives, I highly recommend using a cam button. This takes the wanna-be scuffing moments off the lobe/ lifter interface as the cam wants to move fore and aft. This allows more load space for the lobe to lift the tappet without the tappet having to keep the lobe under it. That will translate into better living conditions for both.

Bogie

[jpd37]

Thanks guys. I will research cam buttons. My motor is a truck motor and it has a flat tappet cam. I do not recall removing anything that looked like a retainer or button. But I'll investigate the button and determine if I can use it, or not. Thanks again.