# Pump gas in an unmolested '68 400?



## Mikesan (Apr 2, 2011)

I've had a few '60's cars, but all of them had rebuilt, restored, or remanufactured engines in them and ran fine on modern pump gas. What do I do with this 25,000 mile '68 I have? It's never been touched other than a time belt (chain) change. Do I add lead or some other additive? California gas normally tops out at 91 octane, but I think I can get 100+ octane nearby.


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## geeteeohguy (Feb 2, 2008)

You should mix the 100 octane with the 91. In addition to 91 octane being lower, it runs leaner due to the alcohol in the fuel, which can lead to lean-detonation issues. I've had a lot of GTO's in CA, and have not been able to run stock ones on pump gas for 25 years or more. You can also try TEL-130. It's the only octane booster that actually does work, but it's not street legal due to it's being lead.


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## Mikesan (Apr 2, 2011)

Thanks. Mix it 50/50?


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## geeteeohguy (Feb 2, 2008)

I'd put 5 gallons of 100 in and 10 galllons of 91 and go from there. This time of year, with cooler temps here, it may be fine. In the summer, you may need more octane with higher ambient temps. I need to run more octane in my '65 in the summer than in the winter.


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## dan woodland (Jul 24, 2013)

*Octane boosters and high test fuels*

I was going to post something about Octane boosters in another thread but this seems to be a good place to ask if anyone used them and what they used.

I have access to 93 or 94 Octane here from the pump. My 69 seems to run fine although I tried a booster in the spring and it seemed to run "quieter". I didn't notice any more power or other effects. 

Is 94 Octane high enough? Or do I need to host it or find 100 Octane?

Geeteeohguy said he used TEL-130. Any others out there that will "work" as well - in case I can't find it here. I did find a brand that says it's not street legal (contains lead) and another that says it's made with lead - which geeteeohguy also mentioned.

Dan


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## Mikesan (Apr 2, 2011)

Thanks GEETEEOHGUY. One last stupid question. I can get either 100 octane leaded or 100 octane unleaded. Would I be OK with the unleaded version? I understand we can't use leaded for on-road use.


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## geeteeohguy (Feb 2, 2008)

Unleaded will be just fine. As for octane, it won't give more power. That is a misconception. Low octane fuel actually burns faster and produces more energy unit for unit. Because it burns fast, it can cause detonation in high compression engines. High octane fuel burns slower....the higher the octane the slower the burn, and therefore will not detonate or 'ping' in a high compression engine. So, high octane will keep an engine from pinging to death and will keep it alive, but won't give you more 'power'. If you can run lower octane without a ping, you will get more power than with high octane in the same engine. Many racers run faster with a better e.t. with 100 octane than they do with 110, etc.


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## Mikesan (Apr 2, 2011)

Much appreciated. I'll be getting unleaded 100 as you suggested and go with it. If you're ever in the Sacramento area with a little free time, give me a call as I'd like to just meet up and say "Hi".


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