Safe comp ratio for an iron headed

[Blown 472]

mota with proper quench in a jet boat??

[76BARRON]

Cam has alot to do with it, but i'd say 10:1 easy and with alot of cam 11:1
should be no problem. Keep in mind I'm shootin from the hip without more info!
I assume your talking about running pump gas?

[76BARRON]

Just noticed your BLOWN 472 name, so if your talking blown then your on your own!

[Blown 472]

Just noticed your BLOWN 472 name, so if your talking blown then your on your own!
no blower, single four.

[LakesOnly]

Tough call blown, depends on so many variables. Generally, 10:1 with those C9' we're discussing and 92 pump gas.
But get this: Pump gas premium is not that much more than AvGas these days, and so you can blend 50/50 and get a resulting 95-96 octane fuel that has 10x the lead pump gas last had. And don't complain about dragging gas cans whenever you go to launch your boat; you live right across the street from the funkin' lake!
By the way, I forgot to mention that I have a very interesting little known trick that I'd like to perform on your heads that may raise your threshold of detonation by a full compression point (yes, pump gas at 11+:1 may be possible). No power loss, no power gain, just detonation resistance by making a change in the head.
LO

[78Eliminator]

I was at 13:1 on my 427 with 990 Iron heads and I hurt it. Several of the exhaust seats were cracked so it was rattling for sure. I would go 11:1, maybe a hair more. Think about it. Production cars are sending them out of the factory with 11:1. Of course, that's with EFI and knock sensors.....

[Fiat48]

The problem is gasoline. Get rid of it. For lawn mowers and transportation vehicles only. It's overpriced and smells bad too.

[78Eliminator]

And it turns your combustion chamber black....

[396_WAYS_TO_SPIT]

The problem is gasoline. Get rid of it. For lawn mowers and transportation vehicles only. It's overpriced and smells bad too.
LMFAO...... That is funny Very true!
396

[396_WAYS_TO_SPIT]

And it turns your combustion chamber black....
Amen!!!!! I ran avgas in my olds for 2 years and it never turned black!!! HMMM I wonder why...........
396