Best Octane for Edelbrock?

[warrenbh]

Hello,

I just got an Edelbrock 600 for my 66 GT.

Should I stick to 93 octane gas??

Thanks for your response.

Warren

 

[blown65]

Octane is dependent on your motor build, not the type of carb you have.

Whats the compression/heads ur running?

93 wont hurt though, but you may be just fine running 89.

 

[j69302]

That depends mostly on your compression ratio and cam specs. List your engines specs.

Running a higher octane does nothing for you unless your engine NEEDS the higher octane.

 

[rbohm]

unless you need 93 octane, dont use it. run the lowest octane fuel you can to save money at the pump, and reduce engine deposits.

 

[warrenbh]

I never realized how little i knew about cars until i bought this mustang.

It's engine was rebuilt by my late friend. I ended up purchasing the car from his parents.

Needless to say, I don't know the specs. All i know is that the engine is blue and a 289 (windsor v8?). My friend put an edelbrock intake manifold on it and added headers.

Maybe I should take it to a performance shop to get more info . . .

 

[warrenbh]

He also added a cam.

 

[blown65]

You could run 89 and watch for signs of detonation by noise, or evidence of speckling of the spark plugs. If they get a peppered look on the porcelain then its got too low of octane or too much timing advance.

No reason to pay for premium if un-needed.

 

[C0V3R]

I find it interesting that you guys have such low octane fuels. 91 octane here is regarded as very low. We have 98 octane for all the sport/euro cars.

Anyway as the guys say, run what you have been running and retune if necessary. The carb shouldnt dictate the fuel used.

 

[65ShelbyClone]

I find it interesting that you guys have such low octane fuels. 91 octane here is regarded as very low. We have 98 octane for all the sport/euro cars.

North America's fuel rating is an average of research and motor octane (R+M/2). Yours is rated only by the research octane so it appears higher than ours, but actually isn't.

 

[D.Hearne]

I find it interesting that you guys have such low octane fuels. 91 octane here is regarded as very low. We have 98 octane for all the sport/euro cars.

Ours used to be as high as yours, but that changed in the early 80's. 93 now is the equivalent of the old 98.

 

[D.Hearne]

Hello,

I just got an Edelbrock 600 for my 66 GT.

Should I stick to 93 octane gas??

Thanks for your response.

Warren

In additon to what everyone else advised you, I'll also add that octane requirement is also dependent on the ignition timing. More advance in the timing usually requires more octane, if your motor's built to use the higher octane. Set the timing at 10-14*BTDC and try a lower octane fuel, but listen for a pinging noise on accelleration. If it pings, then go higher on the octane till it stops pinging. If it pings on 93 at this timing setting, back off the timing til it stops. I run my 331 on 93 with a 10.4 to 1 comp ratio and the timing set at 12-14*BTDC. The 5.0 in my 89 Ranger uses 87 in the winter, 89 in the summer with the same timing setting but a lower comp ratio (9-9.5 to 1) but also with a wider LSA cam (stock F4TE roller)

 

[C0V3R]

North America's fuel rating is an average of research and motor octane (R+M/2). Yours is rated only by the research octane so it appears higher than ours, but actually isn't.

Ah you learn something every day. Interesting!

 

[JonK]

I would also look for stations near you that sell 100% gasoline if it's available and avoid the "may contain up to 10% ethanol". The ethanol will dry out the gaskets in your carb. eventually and you get better mileage from 100% gasoline. Don't know what state you're in though as I've heard some states don't allow octane free gas to be sold, welcome to the new america...
Jon

 

[D.Hearne]

Don't know what state you're in though as I've heard some states don't allow octane free gas to be sold, welcome to the new america...
Jon

Octane free gas ?

 

[JonK]

DOH! amnit:

Typed too fast, meant Ethanol free...
Jon