# pump gas



## simmons68 (Dec 22, 2009)

Hey guys,

I backed my timing off 4 degrees and that made my 68 gto run way better, thanks. My next question is fuel. Should I be adding an octane booster to the pump gas that I am running. When I rebuilt the engine I installed a harder seating valve so I could run pump gas. Do I need an additive? Will it hurt to use an additive every once in a while? Thanks


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## Rukee (Feb 8, 2007)

Whether or not to run the octane booster is more dependent on what compression ratio your motor is running at. If it's a low compression motor, no worries, if it's a high compression motor then yes, maybe even run 50-50 with some race gas. Then you can bump your timing back up.


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## simmons68 (Dec 22, 2009)

My 68 gto has 10.75-1 compression with a mild cam. I was told that Berryman's B-12 is as good octane booster as any. It has something called touraline in it. Will putting a couple of pints of this with every fill up help any? Thanks


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## jetstang (Nov 5, 2008)

Why did you back the timing off, was it pinging? And how does it run better?
If you backed the timing off due to pinging, then you definatelly need higher octane fuel to stop the pinging. The hardenned valve seats are to protect the valves due to not using leaded gas, nothing to due with octane requirement.


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## simmons68 (Dec 22, 2009)

Yes, it was pinging. It does seem to run better, but I think it can still do more. It was also hard to start once it warmed up. My timing now is about 6 advanced at idle. Would you suggest moving my timing back to 10 advanced at idle (where I usually keep it) and use an additive? I appreciate any feedback.

Thanks


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## jetstang (Nov 5, 2008)

6 with advanced removed is stock setting, so that's alright. If you can run that on Premium pump gas you are doing good. Octane/race fuel will make the car faster with the right tune. Anytime you pull good timing, you are also pulling power. If you aren't racing, then this is fine. When you want the car bad, put good gas in and dial the timing back up. My 454 hard cranked, I put a gear reduction starter in it and hard crank went away, so it may be the starter, not the timing.


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## likethat (Oct 5, 2007)

I have been playing with E85 to premium gas. E85 is around 100 octane but is alcohol based. It will harden up filter and rubber lines and promote rust in non stainless lines and the gas tank. We have Sunoco here and they have 94 octane unleaded. So I add about 4 gallons of E85 and the rest 94 for a total of 16 gallons. It helps my 67 Camaro it is running 13:1 on a 427BBC No ping.


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## skyman51 (Jun 12, 2010)

simmons68 said:


> My 68 gto has 10.75-1 compression with a mild cam. I was told that Berryman's B-12 is as good octane booster as any. It has something called touraline in it. Will putting a couple of pints of this with every fill up help any? Thanks


Anything under 11:1 CR will run fine on pump gas at normal engine specs. My 70 Judge Ram Air III runs just fine on 93 pump gas. On the other hand my 70 Chevelle LS6 is 11:25 to 1 CR and I run 50 50 of pump gas and Sunoco Cam II 110 octane leaded. It runs fine with that but must have the lead and octane.


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## Rukee (Feb 8, 2007)

You should only need a lead additive if your heads don't have the hardened exhaust seats.


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## skyman51 (Jun 12, 2010)

Rukee said:


> You should only need a lead additive if your heads don't have the hardened exhaust seats.


Hardened valve seats do prevent damage due to lack of lead to cushion the exhaust valve, but it is an urban legend that this is really a problem. Unless your car is driven as a daily driver, no damage is going to happen rolling it on and off a trailer or driving it to a cruise night several times a season. I would only do the heads if I was rebuilding the engine, otherwise it is a waste of money IMO.


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## allpawl66 (May 9, 2008)

Detonation will destroy that engine , do not take the chance , have it tuned properly , check total timing .


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