Fuel Question
Thread Starter
Intermediate
Joined: Dec 2019
Posts: 27
Likes: 19
From: Shelby Township, Michigan
Fuel Question
General question on what fuel to use. I have a 69 convertible 4 speed with a 350 L46 11:1 Comp ratio. Original engine to the car (HW code non-AC). Engine has been reworked to run unleaded (or so the previous owner told me). No Carb, it has the Holley Sniper EFi system installed. Performance has been great so far.
I had the car about a month and have used 93 premium with 10% ethanol. Less than one fill up so far.
My question is: Should I use non-ethanol fuel? There is a station right around the corner that sells 90 Octane 100% pure unleaded gas.
There is also a station about 5 miles away that sells 110 Octane leaded racing fuel. Are either of these preferred? Can they be mixed together?
I had the car about a month and have used 93 premium with 10% ethanol. Less than one fill up so far.
My question is: Should I use non-ethanol fuel? There is a station right around the corner that sells 90 Octane 100% pure unleaded gas.
There is also a station about 5 miles away that sells 110 Octane leaded racing fuel. Are either of these preferred? Can they be mixed together?
Last edited by michjim72; Aug 17, 2020 at 09:12 PM.
1967 Pedal Car Champion
Joined: Mar 2020
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From: US-PNW
If you're not getting an pre-detonation pinging or knocking then I'd stick with what's easily and economically available. The ethanol isn't great for rubber components and it hurts gas mileage a bit but otherwise is OK.
Unleaded has been the only commonly available fuel for decades, so if the valve seats were going to be destroyed from being non-hardened, then it would have happened long ago.
Unleaded has been the only commonly available fuel for decades, so if the valve seats were going to be destroyed from being non-hardened, then it would have happened long ago.
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From: Sunshine Coast, Queensland, Australia
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Well, perhaps it's just me. But I'll throw my opinion in here as I guess the OP is asking for opinions.
I wouldn't put any alcohol in a old car period!
No Bloody way. Sorry, I've fixed to many that where destroyed by alcohol. These old girls where not built with alcohol in mind. AT ALL!
if you love your baby, buy her the correct fuel.
only the best top grade fuel should go into your car.
that is if you truly love your car.
NONE Alcohol go's into mine.
I wouldn't put any alcohol in a old car period!
No Bloody way. Sorry, I've fixed to many that where destroyed by alcohol. These old girls where not built with alcohol in mind. AT ALL!
if you love your baby, buy her the correct fuel.
only the best top grade fuel should go into your car.
that is if you truly love your car.
NONE Alcohol go's into mine.
Le Mans Master
Joined: Jun 2019
Posts: 5,334
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From: Loveland
Higher octane fuel is for higher compression. At 11:1 you are fine with 93. The higher octane fuels have LESS power,,, so they wont detonate. If a car doesn't detonate on 85 octane it will produce LESS power if you put 110 octane in it. The higher the octane in the fuel the LESS power it has.
Le Mans Master
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From: Loveland
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For the octane, no need for lead unless the engine is constantly under high load, pulling a trailer up a hill for example.
Where I buy it the price for the 110 leaded is less than the 100 unleaded, otherwise the 100 would be fine.
Where I buy it the price for the 110 leaded is less than the 100 unleaded, otherwise the 100 would be fine.
Last edited by MelWff; Aug 19, 2020 at 12:33 PM.
Le Mans Master
Joined: Jun 2019
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From: Loveland
Is that 110 octane aviation fuel? This is a total waste of money, and can hurt your engine. Not cleaner, better, and will give you less power.
Lead deposits will also block oxygen(lambda) sensors and catalytic converters and foul spark plugs even after only a short use. Also, 100LL has a chemical package added to make it perform at high altitude, and that isn't the best thing for motor vehicle performance here on the ground.
Lead deposits will also block oxygen(lambda) sensors and catalytic converters and foul spark plugs even after only a short use. Also, 100LL has a chemical package added to make it perform at high altitude, and that isn't the best thing for motor vehicle performance here on the ground.
Thread Starter
Intermediate
Joined: Dec 2019
Posts: 27
Likes: 19
From: Shelby Township, Michigan
Thanks for the feedback. I think I'm sticking with 93 premium with the 10%E. I think for winter storage it might make sense to empty the tank and then fill it with 90 non-ethanol and add some stabil. Can't believe I'm already thinking about winter storage.
Team Owner
Joined: Jan 2006
Posts: 37,637
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From: Crossville TN
If you use leaded fuel and you have a CAT in the exhaust system, that CAT will be wasted in short order. Your engine needs 93 octane, minimum. You have 11:1 compression with iron heads. Tough to keep that combo from 'pinging' without retarding the spark some. If you can find no-ethanol fuel and can afford it AND the engine functions better with it, go for it. Otherwise, just put the highest octane fuel you can find in your location and adjust timing to eliminate any pre-ignition (pinging).