the 70 mustang fastback that i recentky bought off a guy has a 302 bored out .2 over with cast pistons and rods and a holley carb and mallory ignition.
The enige has been really speced out. the guy claimed it had nearly 350 hp and claimed it would only run with 93 octane fuel with anoctane booster. he aid it wont even start on 89 octane. could this be true? what type fuell do yall run in ur mustang?

 

My 10.8:1 compression motor runs on 91 octane.
If its lucky it gets110 octane at the track.

 

You can run 89 with 350HP. Its all about timing, 32*-34* total. If you bring the timming up to, lets say 38*-40* , I would use 93/96. This is asuming that comp is less then 12.8 and it's not blown/turbo..

 

cast pistons? im gonna guess and say it has flat tops, which means the compression shouldnt be *that* high. and even if a motor needs 100+ to run properly, it would still start up with 87 in it (and go down the road but it would knock/ping)

 

aight... the person i bought it off of is not a real smart guy but told me it was high compression and needed the 93 octane with booster. i just wandered thanx

 

My old 9:3.1 compression ratio 289 runs just fine on 87 octane. I suppose if that one is 11 or so ratio, then the premium would be needed. However, it is bullsh!t to say a car won't even start on 87 octane fuel.

 

i run 93 octane in mine, the motor isnt anything special, it just makes me feel better to run it. (im afraid to run 87)

 

octane booster is crap. if you really NEEDED to bump the octane, ya gotta add in a couple gallons of 100 or higher to blend it. av gas from your local dinky airport works really well but it lacks upper cylinder lubricant found in automotive gas. i wouldnt mix it more than 50/50 but i have done it that way a bunch of times with no ill effects. btw, av gas is usually alot cheaper than race fuel, and its low lead so theres a *little* something to cushion those exhaust seats (which i figure is nice even with hard seats)

reminds of another point. if your motor is original and its pre early 70's, you DO need to use a lead additive or you will pound the crap outta the valve seats and screw up your stuff.

 

I am wondering about the lead in he gas as well. My engine is all original and though the timing is changed to run 87 octane, I wonder about using unleaded.