I have a ~1996 roller block (880 casting) and I'm doing pre-assembly for a 383 stroker. I've got a Cloyes Hex-Adjust double roller timing set, and a cam for hydraulic flat tappets.

First, the Cloyes timing set comes with a thrust bearing, and everything seems to fit OK. However, looking at the crank and cam gears, they don't quite align, and the cam gear is rubbing on the block's thrust plate mounting surface.

Is there some adapter, or shim, that I'm missing here? I'll post some pics (pretty grainy/blurry unfortunately).

Finally, what keeps the cam from walking forward out of the block? Do I need a thrust button? I thought that was only required for roller cams.

 

From your picture, it's hard to clearly see the snout of the cam. The end of a (factory) roller cam is stepped down in diameter to fit the inside diameter of the thrust plate. That portion is also longer so that it comes flush with the front of the plate. Is your cam styled the same as a roller, but just made for flat tappets? Or does your setup leave off the factory plate?
Thrust control is critical with roller lifters, which is why it has the thrust plate. The lobes on a flat tappet cam are slightly angled to keep the cam from walking out. That's not a big deal because flat tappet lifters rotate, roller lifters don't.
Edit: After looking again at your cam gear, I'd say that's the problem because it's deeply recessed where the cam mounts. But then again, I can't tell how flush, or not, the front of your cam is with the block.

 

The cam will sit all the way into the block if you let it. The snout is a single level/diameter with no step. I talked with Lunati (who makes the cam) and he said they didn't make that cam with a roller-block type snout. When you bolt the cam gear onto the snout, with the thrust needle bearing installed, it touches the thrust plate mounting surface, and the gear drags on the block (around the areas with the plugs).

I'd say the cam gear sprocket is about 1/4 inch too far in toward the block in relation to the crank sprocket.

I guess it's my own damn fault for not checking with the cam company and telling them what type of block I had. I guess I should call them back and see what their suggestions are. Trouble is, this is a custom grind and nitrided too, so I can't return it. :-(

 

Did you take this engine apart, and still have the old cam gear? Roller and non-roller cam gears are shaped differently in back where they fit to the cam. Could be you want to use a roller timing gear set. Maybe you can search online for some pictures of the back of the cam gear. And, pulling the cam out to get the gear on isn't going to work. It needs to be all the way in, or the distributor gear won't mesh.

 

No, this is a new build (my first if it wasn't already painfully obvious). :-)

Yea, I was worried about it not seating at the distributor. I'll look around for a different timing gear. Thanks!

Mitch

 

I think I have this figured out. It seems there were two issues:

1. I hadn't driven the crank sprocket fully onto the crank. I drove it an additional distance onto the nose, and it now aligns with the cam sprocket. Whew!

2. I had to grind away a bit of the lower lobe on the water gallery jacket. This was the only place the cam sprocket was actually touching the block. I went around the sprocket with a high intensity light, and found all the spots it was touching (just that one). After grinding about 1/8 inch off at this location, the sprocket clears fine, and all looks good.

Thanks for the feedback 'Camaro 69'!