ez1

Hi All,
I am (have been for the last few months) looking for my first vette. I saw her first in Sept 1970. What a beauty! I was a high school kid working at an automotive supply store and saw her, right off the showroom floor, in the parking lot. I couldn't even speak I was so stunned. I had never seen anything like it. Well, I've arrived (my wife said OK :-) I've been looking on all the autotrader, carsonline etc sites and was wondering what kind of gas does the 454 require. I remember 103 leaded gas back then was desirable. Do I have to buy a 350 to be able to drive into my local gas station to fill up? What do you all use?
Any help would be appreciated.
Thanks,

bence13_33

I believe the compression ratio for a 454 in '70 was around 10.25:1. That is still pump gas friendly. You may need to run 92/93 octane but you shouldn't have any problems with detonation with pump gas.

Larry B.

HI...Most stock BB's through 1970 can (must ) be re-tuned to run on 93 octane. They are sensitive to brands... Amoco seems best for mine. You still need to retard the Total timing and drive conservetivly to avoid pinging. 1971 and later for most part will do just fine on premiun 92-94. When you retard timing performance suffers so if you want you early BB to run like it did in the 60's-70's ... use Cam II 110 octane racing fuel. Mine is the lower compression 427/ 390hp. About the only time I have problems is in the hottest part of the summer. I absolutely cannot use any fuel except Amoco. :hurray:


[Modified by silvervetteman, 4:15 PM 2/22/2003]

zwede

I have a '71 LS-5 454. Factory compression was 8.5:1 and I swapped on a set of aluminum heads which bumped CR to 9.5:1. I'm running fuel injection and programmed a fairly aggressive timing curve. It has never pinged, even lugging the motor at 1000 rpm in 4th in 100 degree heat. So recently I switched to 89 octane instead of 93 and it still doesn't ping.

So as long as you get a '71 or later 454 I'd say it runs on pretty much anything.

ez1

Hi, Thanks for the quick response. I'm looking at the 70 vette. It was the summer of 69 not 70 as I previously mentioned :bb Musta' been something I ate at Woodstock that summer?
As bence13_33 noted the 70 454 has a CR of 10.25:1. I assume that the CR is the factor to consider. No? The 350/350 and 350/370 have a CR of 11.0:1. (I looked these numbers up in the book) Is there a rule of thumb that you all go by?

Robert N

I have the 70 LT-1 (350/370) and run a mix of 91 (best available here) and 100 race fuel to keep her happy.

zwede

Well, there are rules of thumb, but what CR you can get away with on pump gas depends on so many things. For example, the camshaft makes a HUGE difference, as well as in what climate the car is driven, gearing and other things.

As I basic rule of thumb (erring on the safe side) I'd say that a smallblock with iron heads and 9.5:1 Cr will be safe. With aluminum you can bump that to 10.5:1.

The big blocks are slightly more sensitive so I would knock that down maybe 0.2-0.4 ratios.

The above is for engines with mild cams. If you run more cam you can usually increase compression.

ez1

Thanks Guys. Nice looking 71 :cool: Markus

JB

With my stock '69BB at 10.25:1, I absolutely can't get the thing to run on 93 octane without pinging under hard acceleration. I'm currently running a blend of 93 octane and 100 octane blue aviation gas, with a half-bottle of Marvel Mystery Oil thrown in per tank. Works beautifully.

JB