Ok, i have owned a handfull of classic cars and I was always told that classic cars have to run high octane gas, none of the midgrade stuff, or they will not run right, smoke, be a little sluggish and the list goes on. I was just wondering if this is true.
What he said. My car has 10.25 compression from the factory. I have to run high octane gas. If you had say a 1965 300 running as new to factory spec's, you should be fine with regular. By the same token if you have an early smog motor you have a low compression engine and high octane won't help. Like was stated, how it's tuned will have a bearing on this.
As an engine ages, sometimes the octane requirement does increase (due to carbon buildup and that type of thing). If your engine is fairly fresh (built to factory spec's), then you can use "standard" octane. If you've modified things (increased compression, etc.) then obviously your octane requirement goes up as well. So, "it depends"... -BC
I use 89 octane in my 430 ci and it runs great. My question is related to which is the most appropriate motor oil, but I'll start new thread for that. lol
If the engine is a pre 1971 and it has a 2 bbl carb it usually has 9.5 to 1 compression and can get by with 87 octane.... If it has a 4 bbl carb it is higher compression , usually 10.25 or better, and has to have as good as you can buy.... like previously said, you can usually tune to the lower octane stuff, but that is limited by the compression ratio... the old rule of thumb,,,''6 deg. before tdc for a 6 cyl and 8 deg. for an 8cyl.'' usually works... but the performance will go down... and the milage will be affected... 1971 and up are set up to run on lower octane fuel....
Ive got a 69 LeSabre 350-4 it has 10.25 : 1 ratio. I run 93 in it, my question is about leaded gas, would it help, harm or make no difference if I ran some 100LL fuel through it? Edit: 93 octane not 97
Does it smoke any? My only experience with leaded fuels is when I had a 68 Ford Galaxy 500, got it cheap with low miles cause it smoked. Started using lead addtive in regular gas, no more smoke.
The problem with 100LL fuel is that some one has their butt on the line for selling it for street use. EPA reg's and more important, no highway tax. They may slap your wrist, but who ever sells it to you could get in bigger trouble.
