I have a Small Block 400 and a 350 manifold, I was wandering if it would work on the 400?

Question

Thanks for the answer i have been wandering about that for a long time.

Answer 1

yes you could use them but it would reduce your mpg

Answer 2

Yes, Most manifolds for sbc will fit all motors from 283 c.i. to 400 c.i.  

Answer 3

Yes it will work.  If you use 350 heads you will need to drill steam holes in them.  To do this, get a 400 head gasket and drill into the head where the little holes in the gasket are between the combustion chambers.  If you don't, the heads may crack due to lack of cooling.  The 400 blocks do not have water passages only steam holes due to the size of the cylinder bores.

Answer 4

It depends on what year of 350 you have. In either '86 or '87 (whatever year they started using the center bolt valve covers) GM changed the angle that the intake bolt holes were drilled into the heads, so, the angle is different in the manifold too. If your 350 is older than that, the manifold will bolt right up. If not, you can take it to a machine shop and have the angle of the holes in the manifold matched up to the 400 heads. This goes for all small blocks, not just the 400.Also, gas mileage will not be affected as someone else said, after all, it's still a Chevy small block, no mater what manifold is on it A manifold that fits one will fit pretty much all of them.

Also, kevin_57 is right about the steam holes needing to be drilled if you use the 350 heads. This is not hard to do, and, may raise your compression if the heads have smaller combustion chambers. This will increase power basically for free.