I have sbc383 w/ 2valve relief pistons/ .025 deck/ will use .020 head gasket/ with comp flat tappet 286h. I will have 11:1 stat comp. with 8.454 dynamic comp..(w/ IK brodix 200 64cc heads) will this be too much to run on 93 octance gas? should i change cc on heads. Advice?
F bird is right. Sorry but even if it works in Sweden, Miami has very different weather and atmospheric conditions. In the hot muggy Miami air you can cut with a dull knife you will probably have problems. It would probably be ok in Montana or Colorado up in the mountains.
There are things you can do though, if you have E85 nearby you can run some of that with your pump gas and it will quell the detonation. You would have to do some testing with different amounts to see how much you need. Dont worry about screwing anything up, just stay with less than 50% ethanol in the tank and at most you would only have to do some jetting to compensate. It wont hurt a thing in your fuel system either, no matter what people might tell you. An added bonus is you will have less carbon buildup in your engine and quite probably more power. Its an option for you if you decide to go ahead with the heads as they are.
Otherwise you will most likely find you need to retard the timing or run some race gas in it.
im at 13:1 compression with basically same setup
using a 50/50 mix of 116 leaded sunoco maximal race gas and 93 octane unleaded.
my timing is optimal
anything less with the gas mix I gotta retard timing a bit.
but I did install a methanol injection and now able to run a mix of 3/4 93 unleaded and 1/4 of 110 leaded race gas.benifits i noted thus far is that combustion temps are noticably cooler.
able to run lower octane
plugs are clean as a whistle.
able to run optimum timing with lower octane fuel.
only thing is to ensure ample supply of windsheild washer fluid.
its cheap at 1 buck a gallon.
AWESOME.. I will change the Combustion Chamber of the heads to accomidate for a lower compression for all around performance. 10.25:1 sounds good. Any guesses on my horsepower and torque numbers.
11 to 1 compression is a little high but I have built 2 motors in the late 1980's with 11 to 1 compression a 383 Dodge and a stroked 262 small block chevy, and they both worked fine with pump gas. A motor is more forgiving with flat top pistons, pop up pistons will ping. But you have to watch out for carbon build up,if you get ANY pinging run some Sea Foam carbon cleaner threw it.
The only way is to run it. The camshaft is fine to run.
Dale
also aluminumm heads help a bit more than cast iron heads.
IMO i would try your setup then if you do have pinging I would install a water injection setup.
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