JOHN

quote:

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Originally posted by indyphil:
I dont think it should but then some companies are using ethanol as an additive to make the gas cheaper. Ethanol additives make the car run leaner with the same jetting (but not by much). I think the cheaper gas may have the ethanol but Im not a gas expert. I think that may have a slight effect? I would say its probably coincidence. Have the ambient air temps changed at all while you are making these comparisons?

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Air temperature has been about the same while using the different grades of gas. The 3 row rad is clear, 6 bladed flex fan, shroud, 160 stat, 60% water 40% anti freeze and water wetter. Now when I am driving on the highway at 60 MPH the car heats up not boiling over but pretty close. When I drive at up to 50 MPH it stays cool, starts to heat up again when at a light. Bottom rad hose is good and not collapsing and just had the motor professionally flushed out. I just can not get a handle on this PITA cooling problem

JOHN

Pre-ignition (pinging) will make your engine run hotter.

You can't always hear pinging.

quote:

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Originally posted by JCQuinn@work:
Two thoughts on your gas grade vrs temp.

Pre-ignition (pinging) will make your engine run hotter.

You can't always hear pinging.

John

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Will that go back to the grade of gas that I am using? lower octane gas will cause pinging and higher octane will eliminate it. I can not hear any pinging at all with any of the grades of gas, but with the exhaust system and mufflers I have, plus being 85% deaf in my right ear I can not hear much of anything. I do not really want to bump my initial timing up any more than what it is now at 17. When this tank of gas is done I will put in the 94 octane and see what that does. Do you or anybody else have any other suggestions?

JOHN

Way back in pre-historic times CONOCO offered a super premium gas that was higher octane that any other gas available in my area. It was the only gas I could run in my hot rod of that time because the compression was so high. The lower grades all created audible pinging when the engine was under load. Now if you want to use high compression you get to buy $5.00/gallon race gas.

Lower octane (cheaper) gas will be more prone to pinging thats the whole point of higher octane. Octane rating is not an indication of how much power is in the fuel, its an indication of how easily the gas will pre-ignite or detonate. Higher octane allows higher compression ratios and more advanced timing without detonation.

quote:

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Originally posted by indyphil:
What he is saying is that if it is pinging on the cheaper gas that might explain the extra heat, so in this case perhaps retarding timing slightly might help REDUCE temps by reducing the pinging? 17 initial is a lot of timing.

Lower octane (cheaper) gas will be more prone to pinging thats the whole point of higher octane. Octane rating is not an indication of how much power is in the fuel, its an indication of how easily the gas will pre-ignite or detonate. Higher octane allows higher compression ratios and more advanced timing without detonation.

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Should I drop the timing back to about 13 - 14 ?

JOHN

quote:

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Originally posted by johnmustang:
Should I drop the timing back to about 13 - 14 ?

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Yep; maybe even back to 12* initially....
Then take someone with good hearing on a ride with ya to listen for any ping.

If I were you John, I'd run the good stuff through that motor. Early 289 heads with flat top pistons make good compression and were designed for 100+ octane in the first place.

38* total time is too much IMO. I'd back it down to 34* at the most

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1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9"