Sandslot

iTrader: (2)

Can anyone confirm the exhaust manifolds from an 86 305 will fit an 87 305?
I had a few studs break off my 87 manifolds and thought I'd use my leftover 86 manifolds and while they do bolt up (holes line up), there seems to be hard contact point at the top of the manifold edge against the head??? Could this be tied to the change to roller lifters in 87?? Dosen't make sense.

Hoping one of you experts can confirm the part numbers maybe or confirm with experience??

two85z28s

I think the exhaust manifolds changed because the heads changed from perimeter-bolt valve covers to center-bolt valve covers. The '87 heads have a machined surface for the valve covers & might be a little wider than the '86 heads/valve covers. (But I've never tried to use the early manifolds with the later heads, so I don't know if they'll fit.)

You would want to make sure the diameter of the outlets are the same, too. The exhaust manifolds, for each year, are different depending on whether they are for an LG4 or a TPI engine.

I have a GM parts book that I get get the part#s (not casting #s) for you, if you need the part #s.

Sandslot

iTrader: (2)

I did check again and the 86 manifold holes do line up, but will NOT bolt flush to the heads on an 87 engine. I think you're right, the heads might have changed for the center-mounted hold downs....one for the note pad!