question about setting end play on BBC cam

[VDriver66]

Hello all, I have a question about setting the end play on a cam in a 502. I bought a 502 that Im dropping in a '66 hallett flat bottom. The motor has a large solid roller cam in it. It also has the manifold installed. The keyway that bolts to the end of of the water pump shaft is too short to fit onto the key bolted to the cam. I thought I'd just have a longer one machined and put it on the water pump shaft. How tight do the tolerances have to be? I was thinking that the end play on the cam should be about .004" does this sound right? Also, being that the manifold is already installed, can I safely assume the cam is pushed all the way to the back of the motor and just machine in the needed end play between the key and the keyway on the pump shaft? Or should I pull the manifold and wedge the cam back and forth and measure it with a dial indicator (obviously at this point not the option im hoping for). Does what Im saying even make sense? Any help would be appreciated!

[victorfb]

the gen5/6 502 uses a cam thrust plate and no bearing against it. so normally you dont need to set thrust, especially since they use roller lifters. you dont need to remove the intake to measure cam thrust movement, just loosen all the rocker arms. then remove the timing cover. not real easy to do without dropping the oil pan some, but can be done. however, it sounds like you have a timing cover that has a removable access to the cam since your useing a water pump drive system. this is driven off the cam correct? you may have a system that was designed for a mark 4 BBC. the gen6 roller cams are differant at the timing gear end. machined smaller with closer mounting bolt holes. but, the over all length should be the same. i realize i havnt givin much info on how to fix your problem, but some reasons why you may be having the problem to begin with. i would suggest posting this also on the V-drive forums ( if you havnt allready) since it is most common to use a cam driven water pump with that set up.

[VDriver66]

The block is a mark 4 bowtie block. I will try posting in the vdrive forum, thank you.

[DetroitJim]

I think I understand what you are trying to do, need to clear up some confusion.
If your block is a Gen 4 Bowtie, it might be 502 cubic inches, but it's not a late model Gen 5 / 6 502 with a factory roller cam.
What timing cover are you running? It must be a Glenwood or similar, or the depth will be wrong for a Magnaflow pump.
Yes, you do need to control camshaft end play and you will have to do it with whatever is bolted to your front cover.
What water pump are you using? If it is a Magnaflow or Neovane with a single flat blade, there will be about 0.125" end play. You will have to modify something. What I did was to weld some steel onto the tang on the cam mounted drive piece, and grind it to provide end play. You can do all of this without taking off the front cover or intake. Just make it long enough so the pump bottoms out against the front cover, then grind 0.008" to 0.010" clearance. Mine works fine.
DJ

[BDMar]

You absolutely cannot set end play with the rocker arms on and adjusted. The cam will not move back and forth and no you cannot assume the cam is all the way to the rear.
Remove the rockers, remove the water pump, use a depth mic and check the distance to the front of the cam/water pump drive (make sure it is all the way back). Then measure the distance from the mounting flange on the water pump to the end of the drive and make the adjustment. Check the depth of the drive slot to be sure you are checking the place that will be the stop. .006 to .010
Assume nothing....

[VDriver66]

Thanks everyone. I knew deep down that I would have to pull the rockers to make sure, but I guess I was hoping I would not have to. The mounting plate is an Edelbrock (similar to the glenwood) and the pump is a neovane.

[DetroitJim]

You absolutely cannot set end play with the rocker arms on and adjusted. The cam will not move back and forth and no you cannot assume the cam is all the way to the rear.
Remove the rockers, remove the water pump, use a depth mic and check the distance to the front of the cam/water pump drive (make sure it is all the way back). Then measure the distance from the mounting flange on the water pump to the end of the drive and make the adjustment. Check the depth of the drive slot to be sure you are checking the place that will be the stop. .006 to .010
Assume nothing....
Well, me being the lazy dirtbag mechanic that I am, I'd just give it a whack with a big piece of brass and a hammer!
BD is right though, to be absolutely sure loosen the rockers. Good luck!

[MACHINEHEAD]

Use some clay between the drive and gen 5s were flat tappet