myronf

I have a 65 327-300 with 4 sp. all original matching #'s. I was filling it tonite with premium as I have done since I have owned it and wondered whether it really needed premium fuel. Comments appreciated.

Myron

ohiovet

I have a 65 coupe set up as a 300HP on a 350 block with a Powerglide trans.
I run the cheapest regular gas I can fine and it runs great.

Blk63Vette

Hello

Usually 93 octane gas seems like that the best...She does get thirsty...

Powershift

Next time the tank is almost empty, pump in 5 gals of 89 (or 87) octane and let the car tell you what it needs. It will protest and ping if adequate octane is not there. If a problem, you can easily add 93 octane to the tank and be good. If no problems, you have your answer.

Many cars can also be tuned (or detuned) to run on a lower octane gas. If that is your goal, there are things you can do with engine timing and spark map.

Larry

KENS78SILVERANNIV

Not sure why you wouldn't use at least 91 octane Premium gasoline in your engine? It's going to burn more efficiently and cleanly.
Is it the cost? At .10 cents a gallon more for Premium is only going to cost you 2.00 more for a tank full. Seems like money well spent for better performance.

Frankie the Fink

Really ?

At least that's what the commercials say...
And de-tuning a classic Corvette to run cheaper gas should be a felony

TWINRAY

If you have a pre- unleaded gas 10:1+ CR Corvette and don't run the best gas (at least 91 if you can't get 93) you can get for it nowadays, I just don't get it.

myronf

I knew that this post would be controversial. But I figured I would just ask.
1. I alway put premium in, but was wondering what can be used, and what was used in the 60's.

2. I agree with Frankie - Premium will not be cleaner, or make it run more efficiently.

3. Premium is 35-40 cents a gallon more, and 10 10 cents more.

Time for more popcorn.

Frankie the Fink

I use the cheapest gas that doesn't ping/pre-ignite.

I run ethanol-laced, 87 octane all day long in my 270hp solid-lifter, dual quad '61 with nary a complaint from the mill. I run 91 in the split window...but will soon try 87 octane...its a base stock rebuilt 250hp.

There was an interesting case made here a few weeks back that the lower-hp/lower-CR engines may even have a greater need for premium...but the argument got into areas of fuel ignition and "big bang" theory that are above my pay grade...

Powershift

Cliffs Notes:

The high compression engines generally have cams with high intake and exhaust overlap that bleed off some of the compression pressure at lower RPMs. At the higher RPMs or WOT the vacuum advance is out of the picture. Just need to keep the TOTAL INITIAL AND CENTRIFUGAL ADVANCE around 34-36 degrees BTDC. Having the correct van can is also very important to prevent pinging.

I agree the 10:1 compression engines with mild cams can have more problems with the lower octane gas, since the cams are more efficient at the lower/typical daily driver speeds and RPMs with high(er) cylinder pressures.

FWIW.

Larry

MikeM

In the case of the mid year Corvettes, some of that is controlled through a less aggressive spark advance.

My 327/250 runs without problems on 89 E 10. Timing is set to OEM spec at 4* BTDC.

Mike Ward

Many people believe that high octane gas has magical powers which makes it 'better' or 'best'.

The only difference between grades is the resistance to detonation. If an engine doesn't ping on 87, nothing is gained by using a higher grade.

If a person enjoys spending money to feel better, I think Frankie offers an email service that would do just as much good or possibly even more for the same money.

Frankie the Fink

Yes! Send me the extra money you would have spent on unnecessary premium fuel or snake oil additives to engine crankcase, gas tank, or, radiator and I will send you a weekly email stating that "Everything is OK!". Everybody wins..and the net results are the same.

I can fake the "From" address of the email to make it appear it came from your engine for a slight fee.

VetteJohn

Sort of like the OnStar report that new cars send out.

mrtexas

Not true. The only difference between regular and super is the resistance to knocking or octane. No performance difference unless you advance the timing. Super shouldn't be necessary unless you have a very high compression ratio and hear knocking or ping. Any other claimed benefits are oil company propaganda.

I was a chemical engineer in a large Gulf Coast refinery for 31 years and spent a lot of time in optimizing gasoline blends. By optimizing I mean reducing cost for the same product specs. Used to be we could only produce Super for a cost of less than 6ct over regular. Anything above that at the pump is pure profit for you know who.

MikeM

I believe you are saying $.02/gal. spread between regular, mid grade and premium. $.02 ea. step? I had always heard that.

Up until recently, we had a $.10/gal spread on the three grades. Did for years. In the last year, the spread has jumped to $.20/gal between grades, compliments of Marathon oil company who now have a virtual monopoly on gasoline sales in my area since they bought out Ashland Oil some years back.

I can drive 30 miles from here and buy gasoline anywhere for about $.40/gal cheaper. The cheaper gas is coming out of a non Marathon terminal in Nashville.

mrtexas

Another gasoline fable is that Exxon gas comes from an Exxon
refinery. All the name brand gas likely comes from the closest refinery
whatever company to minimize transportation costs. The Oil comanies
have agreements with their competitors to minimize overall transportation costs.
Gasoline is fungible meaning a commodity generic product. Still believe the Oil Company advertisements? They wouldn't advertise unless is paid.

jtranger

We need to switch Frankie to the vendor section, since he is now providing a service!!

SDVette

I agree that you should run the lowest octane gas that DOES NOT cause pre-detonation in your motor. Paying for higher octane than that grade is a waste of money.

People are funny about gas though.... I still remember my dad having to dump the clutch to stop the motor from dieseling after shutdown... He was too cheap to pay for premium.. Which is certainly needed in the 11:1 LT-1 he installed.