Octane requirements 1959 - 283 - carb

[Gary L.]

I am looking for information as to the proper fuel /octain requirements for the 1959, 283 single 4bbl carb engine. In Canada the highest octain I have seen is 94, also as long as any fuel is under the 10% ethinol I would imagine that would be safe for engine operation, or should I be looking at some type of additive?

Thanks in advance,

Gary Logan
Toronto

[Michael W.]

Re: Octane requirements 1959 - 283 - carb

Gary-

94 is more than enough. The guys in the gulf states report problems with vapour lock and percolation when running E10 fuels, not so much here in the great white north.

[Gary L.]

Re: Octane requirements 1959 - 283 - carb

Michael,

Thanks for getting back to me with this information.


Regards,
Gary

[Zachary H.]

Re: Octane requirements 1959 - 283 - carb

Gary,

I am new to this forum and asked a similar question previously as it related to ethanol. I received responses on both sides of this issue. If you do a search on this subject you should find the past threads. There are many more experienced members who will more than likely weigh in on this issue. I have a 1960 283 single 4 barrel carb. I run the pump high test either 92 or 93 which I have been also told is more than enough. I do use an ethanol defender just to error on the side of caution. I have run all summer long this way without any known issues. Hopefully my experience helps in your thought process.

Zach

[Michael W.]

Re: Octane requirements 1959 - 283 - carb

I do use an ethanol defender just to error on the side of caution.

I know of no product that contains anything that will make much difference. They're mostly successful by claiming to avoid problems that wouldn't have happened anyway. I have a fairly large crop of garlic this year. So far not one vampire has been spotted.

[Duke W.]

Re: Octane requirements 1959 - 283 - carb

...sounds like a base 230 HP engine. Advertised CR is 9.5:1, actual as built was probably 9:1, and if it's been rebuilt it is probably lower, so regular unleaded, 87 PON, will probably be sufficient to keep it out of detonation. Many owners of base 283s report that their engines run detonation-free on regular unleaded, 87 PON. The 283/230 is a plain vanilla mildly tuned engine that was used throughout the Chevrolet model line - nothing special.

Let the tank get near empty, put in three gallons and listen for detonation. Repeat a couple of more times. If it doesn't detonate, fill it up with regular unleaded. If you do detect significant detonation try the next high octane which is usually 89.

Most owners don't know to any degree of accuracy many internal engine configuration details, such as actual compression ratio, so each needs to experiment as recommended above. Virtually all vintage Corvette engines will operate fine on pump gas. Many don't need the highest octane and none need any kind of store-bought additive, but a lot of guys still drink the Kool-Aid they get on the Web and various TV and magazine ads anyway.

Duke

[David K.]

[Duke W.]

Re: Octane requirements 1959 - 283 - carb

There are lots of solutions to the E10 percolation issue that some owners experience - spark advance map, heat riser, insulating fuel lines.... It's all in the archives.

Duke

[Gary L.]

Re: Octane requirements 1959 - 283 - carb

Zack,

Thanks for responding, I figured as much however since its my first 59 (4 wheel) after years of running vintage bikes I never had a problem in running the premium fuel, a few cents more and for the insurance its worth the cost.

Thanks again,


Gary

[Gary L.]

Re: Octane requirements 1959 - 283 - carb

Duke,
Thanks I will look into that.
Gary

[Michael W.]

Re: Octane requirements 1959 - 283 - carb

Everyone seems to have varying opinions on gas.

Opinions- yes everyone has at least one. Valid facts are not quite as numerous.

[Gary L.]

Re: Octane requirements 1959 - 283 - carb

How true..

[Domenic T.]

Re: Octane requirements 1959 - 283 - carb

Gary,
I would start at the top and use the best for a few more cents. It was a common practice to mill the heads when they needed to come off and that raised the compression. We milled the maximum when we raced the 283 which was the largest they had in a vette back in 59.
I developed a problem experimenting with a 425 HP big block that has higher compression. I did not de-tune it after running a higher octane fuel and started running our highest test fuel here in the heat of Palm Springs, CA. (91).
My engine did ping under power while accelerating so I stayed out of that area and drove like grandma would. My problem developed when the engine was heat soaked from a long drive, it would diesel when I turned the key to off. It was violent and with a automatic trans I couldn't shut it down with the clutch so I turned the key back on and the engine continued to run normally. It took many tries to get the engine stopped so I would turn the AC on and turn the key off while in low to load it down. The engine noise while dieseling was so loud that I knew I did damage. It did not diesel or ping or diesel with my fuel blended with avgas. I now have piston slap in one cylinder most likely from a bent or cracked piston skirt.
My idle was 1100 which invited the dieseling and I did find a bad vacuum can on the distributer. Had I not been so lazy and de-tuned the engine I wouldn't have to pull the engine.
I will not put the full blame on the fuel as I was experimenting. I de-tuned the engine and replaced the vacuum can and the engine runs without the ping or dieseling, less power but OK. The piston slap is loud when first started (cold) but as the engine warms up and the piston expands it is barely detectable.
I vote for the highest octane at the pump, that's why there is a choice!

Dom

[Gary L.]

Re: Octane requirements 1959 - 283 - carb

Dom,
Thanks for responding and I agree between the 91-94 grade of gas will meet the requirements.

Best Regards,
Gary

[Joe L.]

Re: Octane requirements 1959 - 283 - carb

Dom,
Thanks for responding and I agree between the 91-94 grade of gas will meet the requirements.

Best Regards,
Gary

Gary-------


If you're wise you'll do as Duke advises. Try some 87 octane and see if you get any detonation. If you do not get any detonation (and I'm pretty sure you won't), then 87 octane is all you need. Using a higher octane under such circumstances will do absolutely NOTHING for you except cost you more money.

Sometimes, I think the motivation for folks to use high octane fuel is because it conveys some sort of "prestige" factor. In other words, they feel that they own a Corvette, a high performance car, and they can't really feel right about it unless they put high octane fuel in it.