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Thread: What octane can I get away with??

  1. #1
    Registered User ShortBus's Avatar
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    What octane can I get away with??

    I am looking to put a v8 in my Blazer and I am leaning toward a 383 with a very mild torquey cam (don't have the specs), and edelbrock intake. As of now It has older double hump 64cc chamber heads with 194 valves. They need rebuilt so I was thinkng of going with some older model vortec heads and TBI. I'm even thinking about swaping on a 94'is top end if I can get the computer to work with the displacement of the 383 short block.

    The question here is that I want this to be a mild performace DD and don't want to have to run high octane gas every day just to make it run good. I know compressin, cam, and timing all play in on this so some suggestions would help. I know I'll probably get flamed for this but I would like to stick with 87 for my daily duties. And I'm not looking for a ton of hp out of this engine.

    Thanks, Chad

  2. #2
    It's all about to change winditup57's Avatar
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    Its is gonna depend on how good your 87 gas is. I have had 2 383's and they have both run on it. Is the 383 a Flat top motor or does it have dished pistons? Lobe separation on the cam can be a factor.

    I run 10-1 in my motor now and it doesnt ping on the lower octanes but it does run better on higher.
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  3. #3
    Registered User ShortBus's Avatar
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    I'm pretty sure it has flat top pistons. Even though the engine belongs to my uncle and he built it, his memory isn't the best and what he thinks he put in it may not be. It was built about 8 years ago. The only thing I'm banking on is that is is an '85 block with 400 crank and rods. The 87 around here is supposed to be "the best" Quick Trip and a couple of other places sell the "top tier" gas. What ever that means. But it is supposedly approved by GM, Toyota, and Crysler. But all I know about gas is they sell three grades and they go up in price the higher the octane.

    Like I said for DD duties I don't need huge performace, I just don't want to harm the engine with detonation. If I wanna race it I'll put in the good stuff.

  4. #4
    Registered User Catching Second's Avatar
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    It'd help to know what your compression ratio is. With flat tops though you should be able to run 87. Put 87 in it. If it pings, put high octane in it. :smoker:
    "A true hotrodder wouldn't be content untill he had created a car so violent, so hairy, so totally sick that the very act of dropping the hammer would result in instant death. Anything less results in the need to go faster." - Tony DeFeo

  5. #5
    Senior Member bigjsp's Avatar
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    In theory you want to add some additive to compensate for missing lead in the gas for the double hump valve lubrication

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