Thread: octane

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have used it in a 548 10 to 1 blown 10 of boost 548 14to8 bigblock a 468 12to1 462 11 to1 yes you need to tune it but they are not pump gas engine. on pump gas they would of bunt down for shure on pump gas. if it not more then 10to1 you dont need much octane makes the burn slow and makes heat the more octane the more you can squeeze it so i think he will be ok i have done it many times but reall race fuel would be better so yes it will need to be tune in

I agree Pat, it should be OK when properly tuned. But, keep an eye out for detonation.
I remember a guy from the old neighborhood (east side of Detroit) that had an early Max Wedge Dodge. I seem to remember it ran 13.5:1 compression from the factory! He used to mix half AV gas & half Sunoco 260.. Ran great on that mixture.

no need to appoligize ,any imfo is good. so with avgas i will have to jet up to be on the rich side.is there any info on the benifits of the lead in avgas that helps reduse detonation or increase the octane number wether mixed or strait?

Good one Dyno. We love to ignore that 'theory' stuff about fuel charge DENSITY and volumetric effeciency but you explained it well.

Actually, I can't take the credit for that thread. I found it on the Club Cobra site. But, it was some very good reading.

Originally posted by shevy not heme
Good one Dyno. We love to ignore that 'theory' stuff about fuel charge DENSITY and volumetric effeciency but you explained it well.

may be you but not me .this was the first thing they hammer in are heads at mercury mercruiser school and that pump gas was not the true octane all the time. they where not going to buy any more engine for boats that hammer them self to death. have done many thing and tried them .on this post i will not give out bad info evey thing i post on i have done it many times .YES he will need to tune it in and if not done rigth it could blow it up i would trust avgas in a12 to1 before pump gas for the rigth octane rating

ON A 12.0-1 MOTOR NEEDS 110 OCTANE FUEL, AND NO ONE TALKED ABOUT A TIMING RETARD CONTROL FOR THE BOOST?

every engines is diferent .msd goses in to this if the pistons are dome or flat top how are the head chambers and more on big block i like to start at 36 and 10 on crank and 26 in the dist =36 like to see it all in at 2500 rpm that is the starting point i spend some time on the tops of the pistons i get them smooth like a old bar of soap and get all the junk out of the chambers of the heads and make shure the head gaskets fire ring is got hanging in the bore and cut the deck to O or the pistons down a bit but not to much if the head gaskets are 0.040 run it at0.005 or so