[Harrison_06]

What is the highest you can go with runing 93 pump gas????? On a 302 ford

[EagleAutosports]

Between 10-10.5:1. Any more and you'd be getting into the pinging range.

[1fast50]

it depends what you are running for heads iron or aluiminum and what type of ignition control you have. 10.5:1 on iron heads is a safe bet not saying it cant be pushed a little further. in 1969 the 4v 351 290hp motors ran 10.7:1 from the factory, on my friends aluminum headed 331 he runs 10.8:1 and has no problems he also has a msd timing controller which allows him to take timing out to compensate for bad gas (91-93 oct) or add timing in for race gas when he goes to the track. he drives the car every day.

hope this helps a little

[Harrison_06]

Oh ok im prob gone go with iron heads... an i think the way i want to go is gone have a 10. 1 compression.... so would that be safe without the timing control???

[The Greek]

In my opinion 10:1 would be the absolute limit for an iron headed engine using 93 octane. Some parts of the country only have 92. I think a more comfortable ratio to allow for a little spark advance would be 9.5:1. Again with iron heads. This is without a variable timing advance unit. This may be consertive, but I seem to have a little bit of respect for my pistons.

Years ago, when lead was in the gas, you could get Sunoco 260 with, I think, was 106 Octane. You could actually set a dial on the side of the Sunoco pumps to adjust which Octane fuel you wanted. There was like four different blends to choose from.

The reason some factory HIPO engines came with ratios in the 11s was that your everyday premium gas had a higher Octane, around 100. Things got so bad when gas was going to unleaded in the in the 1970s and 80s that premium wasn't available at all. In the 70s we had two fuel shortages and you couldn't buy gas, anywhere. You'd spot a fuel delivery truck and follow it to see where he was going to deliver some gas so you could get some. Ah, for the good old days. ---Chuck

[EagleAutosports]

I remember those days... I was about 4 or 5.

[BlueStreak03]

My dad has to tell me about those days, it was a little before my time.

[Asheron2]

If you run a huge cam you can get away with running more compression!!! We used to run 14:1 compression in our jet boats, but the cams were so huge that we could get away with it. Its not just about compression ratio, but your actual cylinder pressure.

[The Greek]

Out of curiousity, what was the base timing set at on the boat engines? Your are correct about cyl pressure being part of the equation.