My buddy bought a 1990 Iroc-z thats supposed to be a 305. After some unusually low 14 1/4 mile times that would make it hte fastest 305 in the world we started to think that the previous owner had been mistaken, so after showing him wear to get the head codes (theres no way you can see any block casting numbers in that engine compartment), we found out in the early hours of today he in fact has a 350. As you can imagine he was estatic. It seems that the motor came from a camaro doner being that its complete and appears to have never been touched. Its a TPI motor btw.

The heads decoded as 88+ Gen I 350, 76cc combustion chambers, it also had stamped steel rockers. Our question is whether or not its a roller cam or hydraulic cam. We are praying for hydraulic because that means he can afford to do the cam swap ;) Like I said theres no way he can get to hte block casting numbers so your help is appreciated.

BTW I was thinking a 262 or 256 adv. duration cam would be a nice swap for him? He plans to eventually to put some vortec heads on there which is making me lean toward the 262..

First, I'm guessing you're asking if the motor has a hydraulic roller or a hydraulic flat tappet, correct?

What were the head casting numbers?

If they book out to a 76cc bathtub chamber, chances are good they are the disgusting swirl-port TBI truck heads.

Someone correct me if I'm wrong, but the only way I recall being able to tell a roller motor from a flat tappet was looking down the distributor hole. If you see the spider, shes a roller.... or possibly peeking through an oil drain hole in the head under the valve cover if possible.

theres no way its a truck TBI, it *may* have 64cc chambers, but its 100% TPI and always has been, hte motor literally was unbolted and unplugged than placed into his car, its quite aparant through the little details. I don't have the numbers off hand but I'll try to get them. But yeah we want to know if its a hydraulic roller or just a hydraulic flat tappet, and with his budget we are hoping for the latter :)

What do you mean the spider.. oh is that the metal plate that retains the lifter alignment in a roller? If so yeah I'll get him to check for that..good idea! lol

Ok heres some more info, this is the head:

14101083

This is what GM has to say about it:

http://www.gmgoodwrench.com/perfpartsjsp/partdetail.jsp?cat=9373&sku=10125377&section=Engine%20Parts

the crate motor they list as having that head apparently doesn't exist on the internet.. Anyone?

anything after 87 has a roller cam in it.

aaron

you can put a plain hydraulic flat tappet cam in a "roller" block.

really? I didn't know that, well that makes it easy than, anything special required to do that though?

Anything after '87 CAN have a roller in it. They can go either way and I've seen a lot of each. Most built after about 93 or so are roller, in my experience. Try to shine a flashlight thru some of the oil drainback holes in the head. Roller will have the spider in the lifter valley plus some figure 8 shaped retainers that loop around the lifters. Other than that, if you feel confident in your valve lash setting ability, pull a pushrod and measure it. If it's roller, it'll be about .400 shorter than stock.

does this mean he would need new pushrods with a hydraulic flat-tappet?

Yes you would need new pushrods with a flat tappet if it has roller. Those are the iron L98 heads. Came on TPI 350 camaro/firebirds. I would guess the block is probably roller. You can find alot of info on this motor at www.thirdgen.org. Lots of posts on how to port these too. I'm running a set I ported on my 70 c10. They outperform the 461 camelhumps I had on there by a bunch.