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The Ford Barn (https://www.fordbarn.com/forum/index.php)
-   Model A (1928-31) (https://www.fordbarn.com/forum/forumdisplay.php?f=3)
-   -   87 Octane (https://www.fordbarn.com/forum/showthread.php?t=228354)

Mike V. Florida 09-04-2017 11:14 PM
Re: 87 Octane
 

Quote:
Originally Posted by 1929 (Post 1522971)
I have a 6-1 Head
Still low compression as compared to the 12.5:1 engines that require 91 octane.

TerryH 09-04-2017 11:23 PM
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.

Flathead 09-04-2017 11:54 PM
Re: 87 Octane
 

Quote:
Originally Posted by TerryH (Post 1523105)
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.
Exactly.

Dodge 09-05-2017 12:59 AM
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.

hardtimes 09-05-2017 01:57 AM
Re: 87 Octane
 

Quote:
Originally Posted by 1crosscut (Post 1522947)
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?
8:1 Tod's first iron Winfield. Use ARCO cheapest (87) and runs great, no problems :)!

BILL WILLIAMSON 09-05-2017 09:46 AM
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.

Dodge 09-05-2017 11:27 AM
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

hardtimes 09-05-2017 12:59 PM
Re: 87 Octane
 

Quote:
Originally Posted by Dodge (Post 1523259)
Hey Hard times, have you used a compression gauge to see what your cylinder pressure is with that 8-1 head? Curious
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.

Jeff/Illinois 09-05-2017 01:10 PM
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:)


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