Hi guys, I bought a new custom grind roller cam that I am not sure whether it is for 87+ stock roller applications, or whether it is ground on a retro roller blank. I will check it tomorrow. I suspect it may be on an 87+ OEM type blank, according to the previous owner's recollections.

I was reading that if it is on an 87+ OEM type blank, that it will be necked down to clear the thrust plate, and it will have a different sized (larger?) timing gear dowel pin than my GEN I timing gear. But I can't just slap an 87+ timing set on it because the thickness of the thrust plate, which I can't use, will be missing. I was reading about grinding the ears off a thrust plate and using it as a spacer (super sketchy), and using the 87+ timing gears.

Can't I just use a GEN I timing set, and if the hole is too small for the dowel pin, just drill it out larger?

 

The cam bolt pattern is different.

 

whats wrong with using the thrust plate?

 

There's nothing wring with grinding the ears off of a retainer plate to make a spacer; or making a spacer from scratch out of shim stock or the like; or drilling and tapping your block for the plate (if your block has enough material all the way around the cam for that). Even if there's not enough of that machined surface up there for the plate, you could in theory locate the holes using a retainer plate (or a drawing), drill them, then spot-face them true to a convenient depth, and use spacers like washers behind the plate. I've never tried it but I can't see how it wouldn't work, given the appropriate level of precision.

If you use either of the 1st 2 methods, you'd still need a cam button. Problem is, the 3 sprocket bolts are SO CLOSE together on the factory roller setup, there's no cam button made, that will fit down in among them. However you might be able to take one of the nylon ones and trim it down to fit in there.

Drilling out the dowel pin hole in the sprocket is risky, as that could easily destroy the gear's timing accuracy. An error of just a couple of .001"s can result in the cam CL being several degrees off. I would avoid that if AT ALL possible.

If you bought a cam and somebody ground it on the wrong blank (i.e. you told them it was an original design motor and they ground it on the blank for the 87-up motor) then the smart thing to do is to send it back and have them do it right. If you bought it used and just bought the wrong one, and the PO won't cancel the transaction, then you'll have to do one of those things above, or re-sell it, or just chalk it up to an installment of the Dumba$$ Tax (don't worry, I've been there PLENTY of times myself, as have most all the rest of us who have been doing this for awhile).

 

Dumba.ss tax, I like that. I bought this cam off this board a while ago. I didn't have it ground, the PO did. There is no recourse if it doesn't work. Crap. Thanks for the great info though on the interchanges. I hate 87+ roller set ups!!! I wish chevy had just used slide a link lifters and kept everything the same.

 

yes that would have been great except aftermarket companys would have to stop ripping people off for them. there is no why they can justify the price

 

Okay the end result is, tada! I have a 0.495/0.530" roller cam, brand new custom grind, ground on an 87+ L98/LT1 blank. Sheeit. I'd hate to not use it because, #1, I paid $100 shipped for it, #2, the specs are exactly what I wanted (and it is rated w/ 1.5 rockers, I did not want to have to step up to 1.6 rockers to get decent lift out of the hot cam that I could otherwise find as cheap on ebay).

So I will use an L98 type timing set (which means I am tossing yet another barely used double roller flat tappet timing set out) and grind the ears off the thrust spacer from an L98. I have one of the spacers in the garage somewhere, it's just a matter of finding it.

I found a set of used Speed Pro retrofit hydraulic lifters on Ebay, and paid $160 for them. I was not going to pay $400 for lifters. All they are is a frieking roller lifter with a stamped steel link riveted to each one. That doubles the price?

Now I need a thrust button. I bought a comp cams steel/ball bearing style thrust button. It sounds like that won't work. I'm sure other idiots like me are using L98 style roller cams in pre 87 blocks, are they all filing down plastic thrust buttons to fit?