The Stovebolt Site Forums The Shop Area Engine Shop Leaded gasoline?

My son was at the parts store yesterday and they asked him if we had adjusted the engine to compensate for not having leaded gasoline.

I never even thought about it....

He has a '62 with a 235. What, if anything, can we do to the engine? Or do we need to get a gas additive?

IIRC the leaded gasoline was important for the life of the valves. Did it serve any other function?

JYF, The lead cushions the valves as they hit the valve seats. I'm not certain what year they started using hardened valve seats but I'm certain that somebody on here knows. If your pickup is just a driver, the no-lead will probably not hurt the valve seats, but if it is a hot rod with high RPM's then you will need the hardened valve seats. Otherwise, don't worry, these old Bolts are tough.

Thanks my friend!

We should be okay then.

I have to agree, especially if the engine (or head) has some old miles on it. I have read in some resto books that a valve seat with alot of leaded miles on it will have enough residual lead on or in the seats to keep the engine going. A new head, however should probably have hardened seats put in at some point.

http://www.radford.edu/~wkovarik/papers/kettering.html#tetraethyl

They were likely referring to the fact that the leaded gas had a higher octane rating. The hot V8s of the same era had to be de-tuned to run on the unleaded stuff. Usually reducing the spark advance curve, using a cooler thermostat and fattening up the carb jetting would get some of the engines by on the high-test unleaded. But its a stopgap measure, cuz the V8 engines with over 10:1 CR will still detonate even with band-aid tuning tricks.

On a 235 its unneeded as the compression wasn't high enough to cause detonation anyway. None of the 235s had induction hardened valveseats, cuz they went out of production 10 years before unleaded gasoline. Any high-mile 235 will show SOME valveseat recession if its been used regularly onroad after the advent of unleaded.

My 235 had terrible seat damage, and some exhasut valve warpage due to this. My car saw many hard miles on unleaded gas. Had to have my head reworked when I did the engine the first time. Now the head is the only part of my 235 currently together. *G*

You can set your valves a bit on the loose side if you have mechanical lifters. This leaves them on the seats longer and improves cooling. If you have a 261 it has stellite valves and better water passages so the seats last a bit longer. Most of the time the block and valve guides will wear out first. Don't worry until it is a problem. There is no point in doing a valve job until you actually need one, since they have to put insert seats in it anyway. It won't leave you stranded.