gasoline for 66 tbird 390

[sadeqq]

i recently bought a 66 tbird.... its about time to fill the gas tank up.. what is everyone's opinion on this....

i was told it needs the lead substitute stuff... is that neccessaary and should i just follow the directions on the bottle? also, is it good to put in low octane gas or high octane premium gasoline.

any and all input is appreciated.
thanks
sadeq

[Joe Vandatta]

My 66 with the 390 runs okay on this California regular but there are different mixes for other parts of the country. I do add some Marvel Mystery oil on long trips and have been doing this for years with no bad results. I would try the unleaded regular and if it doesent ping you are okay.
Joe

[RogG]

My '65 runs fine on unleaded premium.

[Captain Mike]

My 390 with 129,000 never-rebuilt miles runs fine on premium unleaded. I add Marvel Mystery Oil to every tankful just to help compression and keep things from getting gummed-up. If you want to improve octane, why not add real lead to your gas instead of a lead substitute. Old-fashioned tetra-ethyl lead was outlawed for autos, but not for boats and marine use. You can buy it by the quart at many marinas or through Auto Krafters at www.autokrafters.com. Good luck.

[Ken Nicoll]

Has your engine ever been rebuilt? I had my 66' 390 rebuilt 2 years ago by a guy that has been rebuilding for over 20 years. His opinion is if you don't use the substitute on originals, it will eventually burn out the exhaust rings. Almost all rebuilds correct the problem so you can use regular unleaded.

[sadeqq]

my car is a 66 with a 390 engine, never been rebuilt... it has 79,000 miles on it.

any more imput or suggestions wouldbe appreciated. thanks to all who have voiced their opinions

sadeq

[64RREDCONV]

My 1964 390 has been rebuilt and runs fine on prem. unleaded.

[woodward bird]

The reason for lead substitute in older engines is to protect the exhaust valve seats,the older engines didnt have hardened seats and with newer unleaded fuel it is said they will be damaged,BUT i have run engines without using it and never had a problem so i guess thats a decision that you will have to make. As far as octane i have run 10.5:1 engines on 89 octane and havent had detonation but wouldnt drop any lower than that. Good luck and congrates on the 66' purchase!

WOODWARD BIRD :D

[bkn_1971]

Use the primum gas and you will be fine .some of the talk is lame I have seen many older engines run fine on hi octane (premi) for years without probs I have even seen street motors on pump gas run well without probs.

[boaterbob]

Originally Posted by bkn_1971

Use the primum gas and you will be fine .some of the talk is lame I have seen many older engines run fine on hi octane (premi) for years without probs I have even seen street motors on pump gas run well without probs.

You should be able to use Premium or Regular in your car depending on how you set your timing.