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Old 01-22-2017, 10:58 PM   #1
ford1933-2008
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Default Retro fitting an 8BA crankshaft into my 42 block?

Gentlemen, Hoping someone out there can provide me with appropriate guidance.

I have a VG 1942 Ford block all tested and good to go. The original crankshaft was badly scored and I was advised to retrofit an 8BA crankshaft and rods to replace my rotating assembly. I managed to locate a stock sized 8BA crankshaft which has been ground and balanced (minus .010"). Notably, the 8BA crankshaft has a single oil slinger whereas my 1942 crankshaft has 2 rear oil slingers

A couple of questions:
1. With the 42 Ford block, which seal retainer(s) do I need? I am advised I need 91A-6335 (Upper seal) which will accept the later 8BA seal. Is this correct?

2. What happens with the lower seal? Does this need to be changed? if so what do I need here?

Thanks for your help

David
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Old 01-22-2017, 11:53 PM   #2
Binx
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

This thread may help...

https://www.fordbarn.com/forum/showth...light=oil+seal

Lonnie
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Old 01-23-2017, 10:53 AM   #3
Ol' Ron
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

The 8BA crank should drop right into a 42 block, using the early main bearings. I question the fact that it's a 42 block. However, Red's headers makes a conversion Kit for this application. Also these early blocks had a different size main journal diameter.
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Old 01-23-2017, 12:01 PM   #4
rotorwrench
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

There were two types of blocks manufactured in 1942 for US and Canadian vehicles. In the US, the 221-cid 81A block and the 29A 239-cid block were utilized. If it came from a 1942 FoMoCo vehicle that can be historically traced back then chances are good that it was manufactured in 1942. If not, a person has to verify by characteristics to be close. Not many vehicles were manufactured for the civilian market in 1942. Ford Canada made most of the Ford equipment for shipment to Australia and they were already in a wartime mode before 1942 manufacturing universal carriers and CMP trucks.
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Old 01-23-2017, 01:06 PM   #5
flatjack9
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

Quote:
Originally Posted by Ol' Ron View Post
The 8BA crank should drop right into a 42 block, using the early main bearings. I question the fact that it's a 42 block. However, Red's headers makes a conversion Kit for this application. Also these early blocks had a different size main journal diameter.
Starting in 1939, all main journals were 2 499. The rod journals were different.
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Old 01-23-2017, 03:31 PM   #6
Walt Dupont--Me.
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

David, yes, the 8BA crank will fit the 42 block, you can use the 59ab aluminum upper rear seal retainer, most flathead places has the special aluminum rear seal retainer for the main cap, use the 42 main bearings, I would use the 49-53 rod bearing and rods. You can use the 4in. Merc crank also, but grind a little notch about an in. long and about 1/16 deep on the bottom of each cylinder so the crank rod nut wont hit the bottom of the cyl. Nothing to it. Walt
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Old 01-24-2017, 03:40 AM   #7
ford1933-2008
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Default Re: Retro fitting an 8BA crankshaft into my 42 block?

Gentlemen,

Thank you very much for your kind advice, much appreciated. I am using a stock 8BA crankshaft, 42 main bearings, 8BA rods and bearings. I am now just waiting on the rear aluminum seal retainer before I assemble.

Thanks again this is such a great forum.
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