Need help with BBC

[DCVING 6]

A buddy of mine has a 73-75 454 in his 72 chevelle. Its obviously a low compression motor. He is getting it re-built, what kind of compression ratio can he run safely on 93 octane.

 

[86brick]

Originally posted by DCVING 6
A buddy of mine has a 73-75 454 in his 72 chevelle. Its obviously a low compression motor. He is getting it re-built, what kind of compression ratio can he run safely on 93 octane.

9.5 - 10.0:1 CR would probably be the highest you'd want to run for a pump gas motor...

 

[EightSecV6]

Cam selection will make a difference too. Alot of overlap will lower cylinder pressure and allow you to run more compression. Iron or aluminum heads?

 

[DCVING 6]

iron heads.

 

[chevyII]

With the big inch, 9.1 would be about the limit. If you used alum. heads or a stupid big cam you could go 9.5.