The Ford Barn

Lawrie · 08-08-2016, 11:14 PM

On my 99a engine it was getting compression into the cooling system ,(as well as a blocked radiator)I did a check and found a crack in one head , the head is 75 cc and I don't have another ,but I have a few 81A ones and some 81T ones,I know the 81T has about 5cc more in the chamber, my engine has a 4in crank and .040 over bore, and I thought the 81T heads would make up for the extra stroke to end up the same as the 81A,s would be on a 3-3/4 stroke engine.
I don't need a speed rocket just a nice smooth engine, any advice.
Thanks Lawrie

scooder · 08-09-2016, 02:03 AM

Lawrie,
Check the cc on the 81A And 81T. All the 81A heads I've measured have 81cc stock, the 81T is as you say bigger, around 85-89cc. 59AB are around 75cc, I'd use these or cut some face off the 81A heads to get um down some.
Martin.

Lawrie · 08-09-2016, 02:28 AM

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Yes thanks Martin, I was a bit slack and did not look at the archives till after I posted,The 81a heads are being acid cleaned in my yard and will be off to the machinist tomorrow.
The 81T heads went back under the bench.
Lawrie

08-08-2016, 11:14 PM	#1
Lawrie Senior Member Join Date: May 2010 Location: Qld, Australia Posts: 4,233	crack in head On my 99a engine it was getting compression into the cooling system ,(as well as a blocked radiator)I did a check and found a crack in one head , the head is 75 cc and I don't have another ,but I have a few 81A ones and some 81T ones,I know the 81T has about 5cc more in the chamber, my engine has a 4in crank and .040 over bore, and I thought the 81T heads would make up for the extra stroke to end up the same as the 81A,s would be on a 3-3/4 stroke engine. I don't need a speed rocket just a nice smooth engine, any advice. Thanks Lawrie

08-09-2016, 02:03 AM	#2
scooder Senior Member Join Date: Jul 2010 Posts: 2,593	Re: crack in head Lawrie, Check the cc on the 81A And 81T. All the 81A heads I've measured have 81cc stock, the 81T is as you say bigger, around 85-89cc. 59AB are around 75cc, I'd use these or cut some face off the 81A heads to get um down some. Martin.

08-09-2016, 02:28 AM	#3
Lawrie Senior Member Join Date: May 2010 Location: Qld, Australia Posts: 4,233	Re: crack in head Sponsored Links (Register now to hide all advertisements) Yes thanks Martin, I was a bit slack and did not look at the archives till after I posted,The 81a heads are being acid cleaned in my yard and will be off to the machinist tomorrow. The 81T heads went back under the bench. Lawrie Last edited by Lawrie; 08-09-2016 at 04:53 AM.