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Mar 1, 2020 | 01:07 PM

crap

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Fuel

What fuel octane should I put in my 1975 corvette stingray? Is 87 ok?I believe that’s what the handbook says,Thanks

Mar 1, 2020 | 01:53 PM

jackson

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From: Unreconstructed, South Carolina

So long as it retains its relatively low OE compression ratio (& hasn't been modified w/ hi-comp pistons/heads) ... 87 OK.

Mar 1, 2020 | 09:03 PM

crap

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Thanks alot

Mar 2, 2020 | 10:30 AM

kodpkd

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From: Loveland

Just don't make the mistake thinking that higher octane fuel has more power. As mentioned, if your engine doesn't have higher compression, putting extra high octane in it will actually give you LESS power.

Mar 3, 2020 | 12:10 PM

vince vette 2

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From: PA

You didn't note if it's an L82, so I am guessing that it's not. However, if it is, the base timing is 12 degrees vs. 6 or so for the L48. On my 80, L82, owned since new, I found that 87 octane would ping at 12 degrees. 89 or 90 worked fine. Today, as I don't drive it that much, I use 90 ethanol free.

Mar 3, 2020 | 02:02 PM

Jebbysan

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From: New Braunfels Texas

Set the timing correctly and see if it pings with 87.......when I say correctly, throw the manual out. Use Lars' papers to set timing for performance and drivability.......stock specs were not really specs at all.

Jebby

Mar 3, 2020 | 05:07 PM

Mrvettenick

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Do you still have the EGR working? That would make a big difference too?

Mar 3, 2020 | 05:50 PM

Bikespace

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From: Virginia

Quote:

Originally Posted by Jebbysan

Octane will cover up problems.When I first got my L48 80, I has to run 93 to prevent run-on/dieseling. She ran HOT. I did the @lars tune, and ran her enough to clean out some of the carbon, and I can get by with ethanol-free 87. The sidepipes are much cooler now, too. I don't think the timing changed more than a few degrees, but it made a difference.

So email @lars, and experiment.