Guess my dad just said screw it new motor

[-83MONTESS-]

If you end up with a true 11:1+ compression ratio you will need higher than premium fuel. Premium fuel around here is 93 octane.

 

[Casey78]

If you end up with a true 11:1+ compression ratio you will need higher than premium fuel. Premium fuel around here is 93 octane.

Its true 11:1

 

[Casey78]

tach works

 

[Casey78]

If you end up with a true 11:1+ compression ratio you will need higher than premium fuel. Premium fuel around here is 93 octane.

Its also aluminum heads so just premium

 

[-83MONTESS-]

Aluminum heads make a difference but not that much. You can get away with it but with today's garbage they call gas 11:1 is high. The general rule of thumb is around 10.25:1 is the limit for pump gas. Obviously there have been people that have gone past that like myself with no issues but it doesn't work for everyone. Ask your dad what the deck clearance measures at and the dome cc. There is no possible way to calculate accurate compression ratios without these measurements. If your dad has engine experience he should have no issue finding these numbers. I could walk you through it if needed.

 

[Casey78]

Aluminum heads make a difference but not that much. You can get away with it but with today's garbage they call gas 11:1 is high. The general rule of thumb is around 10.25:1 is the limit for pump gas. Obviously there have been people that have gone past that like myself with no issues but it doesn't work for everyone. Ask your dad what the deck clearance measures at and the dome cc. There is no possible way to calculate accurate compression ratios without these measurements. If your dad has engine experience he should have no issue finding these numbers. I could walk you through it if needed.

No idea on deck clearance we have never had the heads off

 

[Casey78]

new fuel pump(from the 383) just gonna buy a new one for the new motor

tach at night

 

[Casey78]

 

[Casey78]

We have run the numbers on the block and it came out of 79 conversion van

 

[rfpowerdude]

The general rule of thumb is around 10.25:1 is the limit for pump gas.

Actually, it depends on the cam profile. You can have a 10:1 engine with a cam that causes pinging with good 93 or have a 11:1 engine with a cam that runs fine with decent advance and no pinging.

First question is, what is the cranking compression? With domed pistons, it may have more of a propensity to detonate at lower cranking pressures, but it would be nice to know what cam is in it...