[sabino56]

I just bought an engine reportedly from a 70 Imapla. I'm pretty sure it is the 300 hp engine - it has 186 heads, 4 bolt mains, the good exhaust manifold (ram's head or whatever). I'm not so sure about intake & carb. It has a 4bbl quadrajet. The intake manifold has a small crack and I need to replace it. It has a casting number of 3985577. I have a manifold a friend gave me in the early 70's which has a casting number of 3887771. They look pretty much the same but have differences in area choke spring is mounted.
Can anyone tell me if that is original manifold and what year the other is from?
I attached pics of both manifolds
Thanks!
Ed

[Jmark]

Looks like the run of the mill 70's version q-jet cast iron manifold. There is no road draft tube opening nor is there a front oil filler hole so its not real old. Nothing special, just a regular manifold.

[Hippie]

Without checking the casting numbers the one on the right is probably a '74-'76 as it has the mounting boss for EGR, the newer style divorced choke pad and it's still Chevy Orange. They went 50 states with EGR in '73 IIRC and I'm pretty sure '76 was the last year for Chevy Orange. My '73 PU had EGR but it also had the old style choke pad, my '77 Malibu 350 had that same intake but it was Corporate Blue. Otherwise as far as the runners it's identical to your old intake.

[sabino56]

Thanks. I can buy or make a plate to close off the EGR hole. I'm wondering if the reliefs around the secondarys make a difference. The 70's manifold has a large relief connecting the secondarys on the rear. The rochester carb has a relief in same area for the engine vacuum port. The other unknown age manifold has smaller relief to front side of secondary's.
Do you know reason for differences and if it would make a difference?