Cam install problem need help please.....

[toypwr]

Doing a stroker build on 2001 4.0 block. The original cam had the retention plate and my new cam of course does not (aftermarket cam). I have the retaining bolt with spring and the cam gear rides against the front of the block, so far no problem. But.....with the cover installed and the spring keeping tension against the front of the cam, with a screw driver I can get about an 1/8 inch forward movement out of the cam. Should I try and space my bolt out with shims/washers to take up this space and try and limit it to .005-.010? And if so wouldn't it be better to set this distance with the spring and pin out and then install them to maintain the cam gear against the block. Or is that space for the cam to walk forward normal?

[SilverXJ]

For a factory cam that space is normal. However, I have had a problem with cam walk eating up my cam bearings. I don't know why, but a few other people have experienced it as well. I would replace the spring and pin with a solid pin cut to length to limit end play.

[toypwr]

This is kind of my thoughts as well. Being this is the first time I have encountered this kind of problem I want to make sure I get it right. What is the number for cam end play I should shoot for .005? Whats the max/min? Thank you.

[Torqsplit]

I don't mean to sound contradictory, but concern for this has always intrigued me. The way the distributor/oil pump drive gears are cut, the cam effectively pulls itself into the block and keeps itself seated against the cam sprocket due to the resistance from driving the oil-pump. Do the the lifters overcome this during operation and force the cam forward? Just curious.

[SilverXJ]

What is the number for cam end play I should shoot for .005? Whats the max/min? Thank you.

IIRC I went with .007" when I setup mine up. There is no real spec. .005" sounds good to. You could always compare to a similar engine that has a spec. Or maybe just with the same gear and cam material.

The way the distributor/oil pump drive gears are cut, the cam effectively pulls itself into the block and keeps itself seated against the cam sprocket due to the resistance from driving the oil-pump. Do the the lifters overcome this during operation and force the cam forward? Just curious.

That is technically the way it works, and even the grind of the cam lobes should help pull the cam into the block. However, there is some force that is pushing the cam out the front of the block. Perhaps aggravated by a more aggressive valve train. Originally the 4.2L or 4.0L didn't have the cam pin and spring. It wasn't until there were complaints of a knock sound that it was added. The knock was the cam moving in and out of the block.

[toypwr]

I know that if it moves to much it can break the oil film on the cam causing excess wear somewhat like a shearing force. I don't think that would happen with the cam bearings but can happen for sure on the lobes. If they added the spring to keep the cam from banging the cover I would imagine these thing jump back and forth alot during accel/decel operations and we just don't see it. With this being my first stroker build I want everything to be as good as possible. With all of the info on this site and the help given when needed I hope to have a long living motor. Thanks all for your help.

[SilverXJ]

I know that if it moves to much it can break the oil film on the cam causing excess wear somewhat like a shearing force. I don't think that would happen with the cam bearings but can happen for sure on the lobes.

It can.

Here is another instance of bearing failure. He was using the stock pin and spring. http://www.jeepstrokers.com/forum/viewt ... 176#p34176
Also, my build thread is mostly bearing failures.

[toypwr]

Any bearing failures using the solid set up to limit endplay?

[dwg86]

I don't mean to sound contradictory, but concern for this has always intrigued me. The way the distributor/oil pump drive gears are cut, the cam effectively pulls itself into the block and keeps itself seated against the cam sprocket due to the resistance from driving the oil-pump. Do the the lifters overcome this during operation and force the cam forward? Just curious.

Cams do walk. Every engine that I have torn down that didn't have a retaining device has had evidence of cam walk (bolt hitting timing chain cover). Go look at any amc v8 and you will see marks where the cam bolt has hit the cover(I have rebuilt several). Same goes for sbc. If cam walk wasn't a problem, cam retaining plates wouldn't be neccasary. Cam retaining plates were used on flat tappet cams before roller cams were used (SB ford 302, FE ford 390, Dodge SB V8 318,360).

I have also heard the way flat tappet cams are cut, the lifters are suppossed to help keep the cam in the block.

I'm not trying to sound like a smart a**, I just know cams will walk.

[SilverXJ]

Go look at any amc v8 and you will see marks where the cam bolt has hit the cover(I have rebuilt several).

Ahhh.. that reminded me of an engine we had in the machine shop not long ago. AMC V8. And there was evidence of the cam hitting the cover.

Any bearing failures using the solid set up to limit endplay?

Not that I have heard of. It seemed to have stopped mine.