87 Octane
 

I always use 87 octane in my regular car, and my Model A. Someone I know who owns more then a few old cars ,and Hot Rods, says I should only use in my Model A, High Octane, and add high octane booster due to the fact that there is Ethanol in are gas, and that my motor was newly rebuilt. Is that excessive?

Re: 87 Octane
 

That is a waste of money to use high octane in a low compression motor.

I have talked to more than one person who does not understand that high octane does not mean that the gas is higher quality.

Marc

Re: 87 Octane
 

I would think that it wouldn't explode at the same time as 87 and would throw off the timing and may even be less efficient in a low compression type of engine.

Re: 87 Octane
 

I use the mid range in my Model A and Model T. In the A it keeps it from pinging with a high compression head, and the T won't start on the hand crank when it's hot on the 87 but will star no problem on the 89 octane. This was on the recommendation of a BP tech when I called with the starting problem.
My two cents.

Re: 87 Octane
 

I think corn should be in our food supply, not fuel.
But, I don't see a problem using it [87] in an 'A'. Mine burns anything including all my old stale fuel from the small engines [ but I usually have 90 non-ethanal in them]. But, this corn crap does spoil pretty quickly.

Some folks don't seem to understand gasoline. Low octane burns quickly and contains more BTUs, high octane burns slower.

Re: 87 Octane
 

OH, for the days of STANDARD & CHEVRON Super Ethyl, in the WHITE pump. I know a Guy who calls his WIFE, "SUPER ETHEL"--She LOVES it & she never "PINGS"--LOL
Bill Alone

Re: 87 Octane
 

Bill that's one of your better ones, I'll remember that one. I guess he must have like to pump Ethel.

Re: 87 Octane
 

I hope 87 isn't bad for my engine. I've been using it in my T with a Z head and my A with a B (police) head for many years now. I use 87 in everything except the V-10 motor home that requires mid grade.

Re: 87 Octane
 

Some are telling me, if you have a stock motor its ok, but if your engine has upgrades with higher compression, no. I can only say one thing I know, with my back pack Redmax blower I only use 89, because the store I bought it at says they will void the warranty if you use 87.

Re: 87 Octane
 

Re: 87 Octane
 

The plus of the Model A is the low compression, so detonation is rare. The minus is the gigantic combustion chamber, with a spark plug miles from the far edge of the chamber. This promotes detonation. I'd say- rule of thumb - that a stock compression engine is fine on low octane and a high compression engine would need higher octane. I haven't heard detonation in mine, but most cast iron engines are pretty audible. If it sounds good, don't worry about it.

Re: 87 Octane
 

Re: 87 Octane
 

Since I can't find gas without corn in it, except at the marina, I did a little checking. Around home Marathon gas has the lowest amount of alcohol in it, about 7%. I use that in my Model A with about 4 oz. of MMO per tank. Runs great.
Marty

Re: 87 Octane
 

Marty and others find a gas station close, might have to drive a bit.. https://www.pure-gas.org/index.jsp?stateprov=OH I'm luck I have three where I live. All issues with alky gas have ended years ago and all small engines and the 4 As run great.

Re: 87 Octane
 

I think you're safe with 87

"By the early 1930s, automobile gasoline had an octane reading of 40 and aviation gasoline of 75-80."

http://www.newworldencyclopedia.org/entry/Gasoline

Re: 87 Octane
 

Re: 87 Octane
 

I've never understood the concern about the gas either.The 29-30 automotive journals said gas was running up to about 67 at the time.Phillips was so proud of their gas they even used the octane rating in their name,Phillips 66.Lead was being developed for use in gas,and it wasn't in widespread use at that time either.I just don't seem to notice any difference in the A's with alcohol gas.If I forget to stabilize the cars in the fall when I park them I just start them up in the spring and drive off.A small engine place near me says he is having a lot of trouble with people using av gas in lawn equipment.When he told me that we didn't have time to go into it,but he is getting stuck on warrenty work from trouble the high octane gas is causing.

Re: 87 Octane
 

1929

High octane fuel is more difficult to burn. It is used on high compression engines to help prevent pre-ignition / pinging.
In a high compression engine fuel will want to ignite prematurely due to compression sort of like a diesel engine ignites fuel from pressure.
Using high octane fuel that is more difficult to ignite solves this issue.
Stock Model A's do not have this problem and will run better on the lower octane fuels.
Has anyone had troubles with pre-ignition / pinging with a high compression head on their Model A?

Re: 87 Octane
 

I have a 6-1 Head

Re: 87 Octane
 

You have read it here but there will still be those that refuse to believe that octane is added to fuel to SLOW burning.

http://bestride.com/research/buyers-...e-premium-fuel

Re: 87 Octane
 

Still low compression as compared to the 12.5:1 engines that require 91 octane.

Re: 87 Octane
 

I have had the 5.5 HC head for over 10 years, and have always run 87 octane regular, ethanol gas, with MMO added. Never had a problem pinging, but I am also careful with the spark advance. A 5.5 head may be higher compression in a Model A, but it is still very low compared to anything modern. I cannot imagine any need to run higher octane gas at this point.

Re: 87 Octane
 

Exactly.

Re: 87 Octane
 

Also remember they changed the way they rated octaine some time in the 80's I believe
They used to list the the two different rating methods on the pumps during the change over.
So we are not exactly apples and apples here.

Re: 87 Octane
 

8:1 Tod's first iron Winfield. Use ARCO cheapest (87) and runs great, no problems :)!

Re: 87 Octane
 

During WW-2 gas rationing, some would even add a few gallons of the CHEAPER, non-rationed Coal Oil, (kerosene)
Bill W.

Re: 87 Octane
 

Hey Hard times, have you used a compression gauge to see what your cylinder pressure is with that 8-1 head? Curious

Re: 87 Octane
 

Hey Dodge,
No. I have very old gauge and the rubber(s) are decayed/broken, so can not get any accurate pressure reading.
I'm going to tear this B down, and have Joe Sivils do some improvements (4"/larger intakes, etc) to enhance use of Tod's head, cragar and others. So, those # not important to me right now.

Re: 87 Octane
 

I have an original 'Mann's 68' gasoline globe from the mid-1930's. 68 Octane.

That was hot stuff back then. Today you couldn't light a charcoal fire with it:D

A Model A will sing using today's 87 Octane she loves it:)