The Ford Barn

[email protected] · 01-22-2015, 07:05 PM

How can I tell difference between 59 AB & 59 A engine?

AnthonyG · 01-22-2015, 07:21 PM

Look up post "Difference between a 59ab and stock 46-48 Flathead" dated 05-24-2010, 10:46 AM. It is basically the difference in the head space volume. Here's from the post,

Quote:

That is on the head, indicating a change. 59A-6050-A head marked 59A on casting has 77-79 cc chamber. 59A-6050-B head, marked 59AB, has 73.5-75.5 chamber spec.
I don't know date of change. B head replaced A head for service, too, with note to change both if a head was needed.

southfork · 01-23-2015, 11:43 AM

I bought the flathead v8 motor out of an early 1950s Ford Police car one time. There was a monster-sized generator on the motor and the heads were marked "AOB". Maybe the AOB means high compression heads --- more compression even than A or AB heads???

rotorwrench · 01-23-2015, 12:31 PM

Are you sure it wasn't OBA with an AS suffix? There was a post a week ago or so about the police/emergency package starting in 1950.

There is no difference in the 239 cid engine blocks for the post war period up to 1948. There are 41A 221 cid blocks though and they also have the "59" cast on the back bell.

southfork · 01-24-2015, 01:25 PM

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I double checked the casting on the head of the engine and it is indeed OBAS. Yes, that was discussed at some length here about December 9th in the context of a Possible police package. Thanks for mention of that thread. Apparently the "S" after OBA means "Special", and there MIGHT be some special features on that engine package, including higher compression. What is the compression ratio in an 8BA factory engine, as a point of reference?

01-22-2015, 07:05 PM	#1
[email protected] Junior Member Join Date: Sep 2014 Posts: 25	59AQB v. 59A ??? How can I tell difference between 59 AB & 59 A engine?

01-23-2015, 11:43 AM	#3
southfork Senior Member Join Date: May 2010 Location: Idaho Posts: 416	Re: 59AQB v. 59A ??? I bought the flathead v8 motor out of an early 1950s Ford Police car one time. There was a monster-sized generator on the motor and the heads were marked "AOB". Maybe the AOB means high compression heads --- more compression even than A or AB heads???

01-23-2015, 12:31 PM	#4
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 16,462	Re: 59AQB v. 59A ??? Are you sure it wasn't OBA with an AS suffix? There was a post a week ago or so about the police/emergency package starting in 1950. There is no difference in the 239 cid engine blocks for the post war period up to 1948. There are 41A 221 cid blocks though and they also have the "59" cast on the back bell.

01-24-2015, 01:25 PM	#5
southfork Senior Member Join Date: May 2010 Location: Idaho Posts: 416	Re: 59AQB v. 59A ??? Sponsored Links (Register now to hide all advertisements) I double checked the casting on the head of the engine and it is indeed OBAS. Yes, that was discussed at some length here about December 9th in the context of a Possible police package. Thanks for mention of that thread. Apparently the "S" after OBA means "Special", and there MIGHT be some special features on that engine package, including higher compression. What is the compression ratio in an 8BA factory engine, as a point of reference?