My 305 TPI has centerbolt valve covers, but I read in another post that those covers first came out in 1987. My car was made in March of 1986 so I don't think it was an "updated 1986" model with the '87 block. To my knowledge, I don't think that any of the previous owners have done any modifications to the engine. If they did, what would warrant centerbolt valve covers... new heads and possibly intake? Would I have a roller cam?

 

Well if your 86 is TPI.....then it always had those "center-bolt" valve covers. That's a FI head you have on there.

Not sure about the roller cam but most likely.

 

not true, centerbolts didn't come out till 87 in the f-bodies. mid year 86 vettes had centerbolts and all 87 v8's had centerbolts. more than likely your engine is not factory but it could be that the heads were changed. to bolt your 86 intake to the 87 heads, the center 4 intake bolt holes would have to be elongated so you might see if that appears to have been done. if not, it is possible your car did get the centerbolts being such a late build but I have yet to ever see one. being fuel injected or not makes no difference on stuff like that.

 

Would those four intake bolts be visible without removing the plenum and runners? I can see a few Torx-headed screws on the intake but the holes don't seem to be elongated... There's also what appears to be a bolt hole without a bolt in it ... that can't be good. This is turning out to be quite interesting.

 

This one was assembled in Van Nuys in July of 1986 - about as late in the model year as you'll get, and it is pretty much bone stock. Perimeter bolt covers for sure:



I always said the '86 was the bastard-child of the breed. More evidence? Maybe, but probably not. I'm guessing the heads have been off, or that car is a really rare one, like some type of factory test mule.

 

It would be a good idea to check the numbers on the block. The engine could very well have been replaced under warantee.

 

Where would those numbers be?

 

This is gonna be hard to explain, but I'll give it a shot:

I believe all small block chevy's have a code cast onto them. It is on the drivers side of the block closest to the firewall. It will be difficult to access, because although it's facing up - it's going to be very close to the firewall and down behind the head. Might even take a flashlight, a mirror and the ability to rear backwards and upside down!

HTH...