Another Classic Car Question: Fuel?
May 13, 2011 
2 Comments
Question by minipoof_saddlebreds_and_buses: Another Classic Car Question: Fuel?
Hey,
I have another classic car question. Okay, cars before 1970 were all run on leaded fuel, right? I’ve been looking into getting a car from the mid 50′s, and was wondering how it is possible to run on unleaded fuel, and if there were any expensive changes that would need to be made. We have a 1964 and a half mustang, but when my Pa was alive, I never remember him talking about the fuels- just talking about the difference between fuel injections and carbeurators. And that’s been a long time! So can any one help me out here? The cars I’m looking at are usualyl around 1950- 1955 and are restored as close as they were-NOT with fuel injectin engines and “hot rod” styling. *blech* (What’s the point)
Okay, I was talking to our school bus mechanic and he said something about heads, but didn’t have time to explain. Is it on the pistons, and you replace them so there is less wear and tear on the engine?
Best answer:
Answer by Vipassana
Depends on how classic you want to go.
Nothing wrong with putting a carbureted 350 engine in a 1950-1955 car.
It’ll look appropriate for the year, run on pump gas, and not have any fuel injection to mess with.
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you will need to change the valve seat’s in the head’s in oder to run today’s gas in those motors if you plan to use the origanal motor.
Your bus driver is probably talking about valve seat erosion. Most manufacturers started using hardened valve seats in the late ’70′s, but most cars designed for leaded fuels run fine without hardened seats unless they are subjected to severe service.
The bigger issue is with the octane rating of today’s unleaded fuels. 93 is pretty much tops and a lot of these older engines were designed when they were selling 105 and better at the pumps. This can lead to detonation which can wreck pistons and bearings. If the car you are looking at was designed for more than about 95 octane you’d need to use some kind of octane booster, use race fuel or rebuild the engine with a lower compression ratio. You can detune the engine a little to get it run on slightly lower octane, but this causes overheating and poor performance.