MF64VETTE

What is the best octane of gas for my 1964 Vette with 327/300 hp engine. I have been using 94 octane since I bought it last summer. But I've been running into problems with it hiccupping when I decelerate and it occasionally backfires. Is it the 94 octane? :confused:

Curtis

I am running 93 or 94 octane in my 350/350 (RPM intake and cam and 750 carb and camelback heads) and I have no problems. I prefer Amoco 93 over most all, but I would say it isn't the gas. You may have a timing problem, carb adjustment or something else.

93 octane should be more than enough.
Curt

waynec

The symptoms you cite are not likely to be related to gasoline octane.
I agree with Curtis, it's timing or carburetor-related.

StrayDog

your power valve may be bad, if your spark advance is to quick & your vac advance connected to manifold vac , periodic backfire occurs, a timed port connection is prefered . :seeya

gilbybarr

I run 93 in my '65 327/300hp. No problems...I do use some real lead but just for my own peace of mind....probably something else causing your problem.

Viet Nam Vett

I use 93 octane in my 65 dual Quad Cp which is the highest I can get in my area, No problems at all. Sounds like your problem is not Fuel related.


65 Dual Quad Cp. 86 Vortec Blown Cp.

RoadVettes

I have a 327/300 in my 67 and I had the same problem. Found out my stock holly carb was way too rich. Adjusting air/fuel mixture solved the problem. I always use 93 octane Amoco or Mobil and the car runs fine.

ghostrider20

I use this crutch to get me close to finding a fuel problem like yours.

-Backfire, Timing to far retarded, or to rich of mixture.

-Pop out of carb, - Timing to far advaced or to lean.

I don't think fuel octane is your problem.

Mark.

MF64VETTE

How did you find out your carb was way too rich? How do you adjust the fuel/air mixture?
I am a novice at this but willing to learn all I can.

RoadVettes

I went to my friends service station and he hooked the car up to his emissions machine (part of NY state inspection for cars less then 25 years old). Took a reading on the Hydro Carbons (this measures how much fuel is being used), and my car was way off the charts. To adjust this there are 2 small screws, one on each side of the carb. Turn one way to lean or the other way to rich. Did this while still on the machine.
There might be other ways to get these readings but the adjustments are very easy. Good Luck, and let us know how you make out.


[Modified by user9ryan, 9:09 PM 5/13/2002]

62fuelie

Those screws only affect the fuel/air ratio at idle. If the carb is too rich at cruise, a change in jetting is probably in order.

Tom/99

I am using 93 octane Shell or Exxon gas, in my 65 Coupe 327/300 with no problems at all.

ARed64

I have a 64 327/300 also. I run premium unleaded, 93 octane with no problems.

midyearinterest

On the left coast the highest octane is 91. The 327/300 runs fine on the pump gas from 76 or Chevron. So I agree with the above posts The ignition is retarded to accomplish this.

Vetterodder

My `65 327 has pop up pistons with an .039 gasket for 10.35 cr. I've had no problems with 91 octane and 37º total timing.

MF64VETTE

Thanks for your post. I took my car to my mechanic for a LOF and asked him to check the timing. Turned out two of the new spark plugs put in lin ate November had fouled. He replaced all of them and reset the timing and dwell. Voila! The engine runs smooth as silk, no hesitation or rough idle. He suggested that I add some leaded fuel additive to the tank once in a while. Do you use that? If so, what do you use and where do you buy it?

RoadVettes

Glad to here your problem is fixed. I was also fouling plugs very fast because of the rich fuel mixture (black carbon deposits on plugs) before I fixed it.
I haven't used any lead additives so I can't advise you on that. :seeya

ghostrider20

I set my mixture via a vacuum gauge and the curb idle screw.

I first let the car warm up, then hook up my vacuum gauge.
I note the reading and then begin small adjustments of the idle/air screws.
I let the car stabablize for a minute and check the vacuum gauge for a drop or increase. I tune for the highest vacuum. If the car idles up, I re-set the idle speed via the curb idle screw and repeat the first steps.

Mark

midyearinterest

Every time I have put in a lead substitute or octane boost my engine runs rough until I flush it out with two tankfulls of un- tainted gas. Used to be I'd go through the carb adjustment, timing etc... just to try to get the engine back to where it was before the additive. My mechanic just chuckels. You would think I'd learn the first time, but I am ever hopeful I'll find a secret potion for even more power. There isn't one. Some folks do swear by Poddels real lead but I have not tried it and probably won't.

396 RAT

midyearinterest, Were about 30 miles apart, I find the additives do help,
(a little) and am real close to putting in an order for a case from Poddels.
Just curious, what brand of 91 octane are you buying? As I would like to
fill her up today.
Thanks

BTW. are you going to the Vette show at Sea Port Village Sunday?