Upgrade Suggestions?

[detmatt]

Everything big block after ‘67 was open chamber and this is the first I’ve heard of there being any difference between port sizes or how much they were cleaned after casting between the 350 & 375 horse application.

 

[The Goose]

Everything big block after ‘67 was open chamber and this is the first I’ve heard of there being any difference between port sizes or how much they were cleaned after casting between the 350 & 375 horse application.

Yep that's what I meant. We were told you could add 67 heads to bump the compression never tried it though. If I remember right my brothers HP 383's all (1970) had the 906s too.

 

[moper]

Everything big block after ‘67 was open chamber and this is the first I’ve heard of there being any difference between port sizes or how much they were cleaned after casting between the 350 & 375 horse application.

That's because it's not true. Never was. The differences in ratings were mostly hype, although different manifold and air cleaner packages and CA emissions vs non-CA did make some minor differences. It's basically packaging differences.

 

[detmatt]

That's because it's not true. Never was. The differences in ratings were mostly hype, although different manifold and air cleaner packages and CA emissions vs non-CA did make some minor differences. It's basically packaging differences.

This much I did know.

 

[bajajoaquin]

I would have guessed the differences were accounted by the several small obvious differences without need for head changes. Everyone mocks the HP manifolds for only making 5 more HP than the logs. The dual snorkel is probably worth 5 more. The 375 cam the remainder?