Kid Thunder

I have a 67 Cutlass 330 2bbl motor. What is your thoughts on using unleaded fuel in these engines before they were set up with different valve & valve seat material?
Should any gas supplants. be used & what is out there?
Don-M

oldcutlass

No additives or supplements will be necessary, just stick with E10 and run the highest grade available in your area. There has been many years of data and the these old engines run just fine on it. The only issues have been the original rubber parts need to be upgraded so that it's more compatible with todays fuels.

BangScreech4-4-2

Yeah, I second. Just drive it without worry until it's time for a rebuild -- however, at the time of the rebuild, I WOULD go with hardened valve seats, just for a little extra peace of mind.

jaunty75

If by "grade" you mean octane, I question whether even this is necessary. If the car was designed to run on regular fuel, then put in regular fuel. If it required premium originally, put in premium now. There is no advantage to putting premium fuel in a car not designed for it.

crimsoncolby

Be reminded that, if the car will sit for months on end without being driven (such as winter storage), you might want to put an additive in the tank to absorb the moisture that ethanol attracts. It doesn't store very well, otherwise.

jaunty75

This is good advice and was true even before the advent of ethanol in gasoline. There's almost always some water in the gas in your tank, and it gets removed as the gas is burned in regular use. But when the car sits, the oil and water separate, and the water, being more dense, settles to the bottom of the tank, where it can cause rust.

oldcutlass

There were 2 - 330's with 2v carbs one was 9:1 and the other 10.25:1 compression. I'd run at least the 89 and 93 won't hurt.

jaunty75

I don't mean to be picky here, and I know this debate has been endless, but I've heard, and it's always been a convincing argument to me, that running fuel designed for a higher compression engine in a low compression engine can hurt. The higher octane fuel doesn't combust completely in the low compression engine, and that leads to carbon build-up which can lead to hot spots and potential overheating.

"It won't hurt" is hardly a reason to use something that's otherwise unnecessary. Not to mention the fact that you're paying more for the higher octane fuel while gaining no advantage.

If someone can give me a clear reason why using premium fuel in an engine designed for regular is a good thing to do, I'm listening.

And, yes, I know there were both high and low compression versions of the 330. I'm assuming he has the low compression version. I assume he knows which one he has.

nj67

I am by no means any sort of expert but last summer I decided to be cheap and start running regular instead of premium (higher octane). After second tank I started getting run on / dieseling, switched back and problem went away.

70cutty

I doubt that these cars were designed to run on today's fuel.

jaunty75

Maybe not, but the answer isn't to automatically assume that higher octane is the solution or is "better."

jaunty75

This solution may only be masking the problem. If your car was designed to run on regular and it runs on/diesels, it sounds like it needs a tune-up, although there are other reasons why this could happen.

Interestingly, run-on/dieseling IS a possible symptom of carbon build-up which could be due to extended use of premium fuel in a low-compression engine as I mentioned above. Run-on can be caused by the engine being too hot, thus igniting the fuel without a spark the way a diesel engine does (hence the name!). An engine running too hot can be the result of carbon build-up.

Another result of carbon build-up is a decrease in combustion chamber volume, which means an increase in compression ratio. That may be why premium fuel works better in your engine than regular. It's been turned into a higher-compression engine by incorrect use of the wrong grade of fuel.

You haven't said very much about your situation, so I'm only speculating here, but it is interesting that your situation could be a classic example of why the use of premium fuel in a low-compression engine is not only a waste of money but can actually be harmful.

Fun71

I am wondering about this. Ethanol, being an alcohol, mixes with water. Exactly what additive are you going to put into the tank to absorb the moisture when the ethanol is already absorbing moisture in the tank.

nj67

I at the time contributed the problem to change in fuel but I also did a tune up shortly after I had experienced the problem. Maybe the fuel change was just coincidence.

drop top olds

Seafoam is a good fuel additive to remove water from gasoline. It can also be used as a top end engine cleaner when injested in a vacuum line into the intake manifold.

I have talked to engine builders about hardened seats on the #6 heads I have in the garage. When the #6's were rebuilt my machinist told me the seats were very hard and he only recommended using a hardened seat when the valve seat was too damaged to be cleaned up.

jaunty75

This is a good question. I'm not sure that the purpose of fuel stabilizers like Sta-bil is to absorb water. You actually don't want water being absorbed into anything. It's better if any moisture you have in the tank stays emulsified in the gasoline so it doesn't come into contact with the tank walls.

I've been doing a lot of searching, and while I can find lots of forums and comments about how wonderful Sta-bil is, one thing I haven't yet found is a description of how it actually works chemically. It would be interesting to know.

jaunty75

I don't mean to rain on your parade or anything. It's just that a properly tuned car should not experience dieseling.

Here's a page describing five causes of it.

http://mgaguru.com/mgtech/engine/ro101.htm

You did letter c. You put low octane fuel in an engine that had been running high octane. But the question is, should your engine be running premium fuel? If it shouldn't but you need to use it now to prevent dieseling, you may have an underlying problem.

Note letter b on that list. Heck, we all use E-10 gas now unless you can find a station selling the pure.

Look at letter e on the list. "Hot spots in the combustion chamber," and his reason #2 below that as to a possible cause of hot spots. Carbon build-up! He doesn't give any reasons for what can cause carbon build-up, but one possibility is incomplete combustion.

Kid Thunder

Wow! Thanks for all the info. I didn't expect so many posts.
I've been a bike guy for the last 45 years or so & the same controversy goes on in those forums.
I do run Sta-bil for ethanol fuel for years & I do swear by it. It does work. I've gotten in many bike that didn't use it for the winter & have had to do many carb rebuilds or clogged injectors.
I will use it in my car.
How I heard & read it works(take with a grain of salt)is that it surrounds the water molecules & then is burned in the engine but keeps the water from coming in contact with anything.
Sorry Eric, but using much higher octane is of no use. But using the "Top Tier" fuels is a good idea. (Goggle Top Tier fuel).
I was just worried about not enough carbon!!
Thanks,
Don-M

Fun71

This is the first mention of Sta-Bil and I don't think anyone said it was used to remove moisture from gasoline. It is used to stabilize the hydrocarbons so that they do not break down over time as untreated gasoline does.

From the StaBil web site:

Our stabilizers and treatments each contain a powerful mix of additives and chemicals that neutralize acids, prevent gasoline from oxidizing and coat metal surfaces to prevent corrosion.

I was originally trying to make folks think a bit.

We all know that gasoline and water do not mix.
We also know that if you get water in the tank, using something like Dry Gas will cause the water to be removed by mixing the water with the gas, then burning it in the engine along with the gas.

We also know that Dry Gas does this because it contains alcohol, and alcohol mixes with both gasoline and water, so it holds the water in suspension in the gas.

Now this brings us to E-10.

We know it has 10% ethanol.
We know ethanol is an alcohol.
We know that alcohol will mix with both gasoline and water.
We know Dry Gas is made of alcohol.

So it's as if E-10 has Dry Gas already built into it.

Kid Thunder

So why are we having with water trouble in our gas if ethanol is the same as Dry Gas? Is Dry Gas still on the market?

Fun71

I am not sure what you are asking.

Water will get into the gas tank for various reasons, such as condensation.

With 100% gasoline, water in the tank ends up on the bottom of the tank with the gas floating on top of it due to the density differences and because gasoline and water do not mix. In order to get rid of the water, an alcohol based additive is use to mix the water with gas so the water is removed along with the gas being burned.

Water in the tank with an ethanol blend fuel results in the water mixing into the fuel and being dispersed in it. The water is removed along with the gas being burned.

So what I am getting at it is the same end result.

oldcutlass

Yes, dry gas is still sold at parts stores. Sometimes called gas line antifreeze.

jaunty75

Good questions.

"Dry Gas," which is brand name, is basically alcohol. It's purpose is to absorb any water and help prevent it from freezing. According to this article, there is no point in adding it to ethanol-based fuels, which are all around us these days. Kind of wonder why Dry Gas is still on the market.

http://www.wikiwand.com/en/Dry_gas