leaded gas question

[DeesZ]

My '72 runs very well on 87. Unleaded is all I can get anymore. I put some Marvel Mystery Oil in every other tank or so for some top end lubricant that I feel is missing since the lead has been removed and the alcohol has been added. I also use MMO in my carbs in the winter (3in1 in the summer). MMO seems high in detergents and also tends to keep things fairly clean.

[MikeW]

however if you want more performance, you can run AV-GAS that has the higher octane levels.

Higher octane does not provide increased performance if your car does not pre-detonate on lower octane. Higher octane means that the fuel/air mixture is harder to ignite.

[Bonzi Lon]

I've put 335 miles on my newly rebuilt engine, (1980) head work, cam #13001-N3626, round tops (new sig?) and used 87 octane, no other "treatments", and have yet to hear it ping, and it has only been SHELL!!!

Bonzi Lon

[Carl Beck]

I think Arne answered your question at Post #6. I'll only add that unless you want to retard your timing - I'd stick with super-unleaded.

FWIW,

Carl B.

[deadflo]

Ive been running the 87 octane with timing set at 10 BTDC in my 71. Never had any pinging issues.

[sblake01]

I run 87 in both the Z and the 810 with no problems but they're both EFI dish piston cars. Believe or not, I have to run premium in the old 320. Head work, fixed breaker plate, centrifugal advance only, Weber carb etc.

[Poindexter]

After running nothing but 93 since getting her on the road- I felt the need to mess with perfection and tried a couple of gallons of 89- and kept some octane-boost handy. Well, the pre-detonation was so intense that the exhaust pipe was banging into the wheel well- I have the "slipstream positioned" pipe tip coming out behind the LR tire. I immediately pulled over and added the booster. Later I filled up with 93 and added half a can of Seafoam to the gas tank to clean it out- and she ran like a champ again.

I will NEVER do that again. I believe that I might have blown the engine or at least a piston or two from excessive pre-detonation, according to several horror stories I've read around here.

All this from a numbers-matching 2/71 L-24 engine with a stock compression ratio of supposedly 9.0- I would have thought the reaction would not have been so violent. I wish Sunoco had their 94 around- that always gave me the best performance on all of my older cars. I used to have a Mercedes 6.9- which was a 1970's vintage 450SEL with a 7-liter racing engine and adjustable suspension, and it loved the 94 too.