The Ford Barn

daveymc29 · 07-10-2014, 03:45 PM

Will a Model B crankshaft work in a Model A block. Any real changes necessary?

Joe K · 07-10-2014, 03:50 PM

Other than the obvious (journal/rod diameters) the only other issue I've heard of is a tendency of the rods to hit against the sides of the crankcase. I believe the B block is relieved a bit for clearance at this place.

It is possible to compensate for this.

I explored the option but have yet to act on it.

Joe K

Purdy Swoft · 07-10-2014, 03:53 PM

The main beartings will need to be cut down to model A size. You will need model B or aftermarket special connecting rods. If model B rods are used, special rod nuts will be needed or the oil pan will need some minor mods to clear.

Joe K · 07-10-2014, 03:54 PM

A quick look to refresh my memory confirms Purdy on this.

See http://www.jalopyjournal.com/forum/t...engine.506451/

Joe K

Chris Haynes · 07-10-2014, 04:20 PM

Quote:

Originally Posted by Purdy Swoft

The main beartings will need to be cut down to model A size. You will need model B or aftermarket special connecting rods. If model B rods are used, special rod nuts will be needed or the oil pan will need some minor mods to clear.

The minor mods of the oil pan are extremely minor. Bolt the pan in place and turn over the engine. A rod will hit the pan. Remove the pan and with a ball peen hammer install some clearance for the rod. You will have to R&R the pan at least 8 times to get all you locations marked. Not rocket science.

daveymc29 · 07-10-2014, 06:24 PM

Sponsored Links (Register now to hide all advertisements)

Thanks, it all sounds rather simple, just time consuming and a few bucks for the machining.

hardtimes · 07-10-2014, 06:37 PM

Quote:

Originally Posted by daveymc29

Thanks, it all sounds rather simple, just time consuming and a few bucks for the machining.

Hey davey,
The rods will clear block, but will touch pan..ergo pan dimples, as said. You will have the benefit of larger/stronger rod journals and use any B crank that you wish to do this, i.e.- Ford first edition..without counterweights, right up thru C crank.

If I were you, I'd get a copy of member Jim Brierley's book and you will not only have answers to the instant inquiry....but much/much more, IMO

! And, if you do not comprehend what you are reading (my problem,eh

!), you can contact Jim B to clarify such. He (Mr. F.A.S.T.) is easy to talk to and most knowledgeable !

Purdy Swoft · 07-10-2014, 07:02 PM

The beaver tail crankshaft isn't a mobel B crankshaft. The beaver tail crankshaft was used in 1928 and has the same journal sizes as the later model A crankshaft

Gavin · 07-11-2014, 02:22 AM

daveymc29,

I recently did this. Had the mains ground to standard A size and used Snyders B rods which had nuts that did not contact the sump. Also fitted a modern rear seal which I hope will not leak too much. I expect to run this engine in the next month or so.

Cheers,
Gavin

colin1928 · 07-11-2014, 02:38 AM

The oil slinger is a different size and needs to be machined to fit the A block if it is off by just a few thou diameter, thickness and taper it will leak
find a machine shop that has done this
or you have you have it machined for a modern seal easier

Jim Brierley · 07-11-2014, 09:02 AM

use ARP nuts, the 12-point kind and they clear the A pan with no mods needed.

07-10-2014, 03:45 PM	#1
daveymc29 Senior Member Join Date: Sep 2010 Location: Danville, CA Posts: 1,557	Model B Crankshaft Will a Model B crankshaft work in a Model A block. Any real changes necessary?

07-10-2014, 03:50 PM	#2
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Model B Crankshaft Other than the obvious (journal/rod diameters) the only other issue I've heard of is a tendency of the rods to hit against the sides of the crankcase. I believe the B block is relieved a bit for clearance at this place. It is possible to compensate for this. I explored the option but have yet to act on it. Joe K __________________ Shudda kept the horse.

07-10-2014, 03:53 PM	#3
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Model B Crankshaft The main beartings will need to be cut down to model A size. You will need model B or aftermarket special connecting rods. If model B rods are used, special rod nuts will be needed or the oil pan will need some minor mods to clear.

07-10-2014, 03:54 PM	#4
Joe K Senior Member Join Date: Jul 2010 Location: Cow Hampshire Posts: 4,188	Re: Model B Crankshaft A quick look to refresh my memory confirms Purdy on this. See http://www.jalopyjournal.com/forum/t...engine.506451/ Joe K __________________ Shudda kept the horse.

07-10-2014, 06:24 PM	#6
daveymc29 Senior Member Join Date: Sep 2010 Location: Danville, CA Posts: 1,557	Re: Model B Crankshaft Sponsored Links (Register now to hide all advertisements) Thanks, it all sounds rather simple, just time consuming and a few bucks for the machining.

07-10-2014, 07:02 PM	#8
Purdy Swoft Senior Member Join Date: May 2010 Location: Alabama Posts: 8,099	Re: Model B Crankshaft The beaver tail crankshaft isn't a mobel B crankshaft. The beaver tail crankshaft was used in 1928 and has the same journal sizes as the later model A crankshaft Last edited by Purdy Swoft; 07-10-2014 at 09:52 PM.

07-11-2014, 02:22 AM	#9
Gavin Member Join Date: Oct 2010 Location: Red Beach New Zealand Posts: 31	Re: Model B Crankshaft daveymc29, I recently did this. Had the mains ground to standard A size and used Snyders B rods which had nuts that did not contact the sump. Also fitted a modern rear seal which I hope will not leak too much. I expect to run this engine in the next month or so. Cheers, Gavin

07-11-2014, 02:38 AM	#10
colin1928 Senior Member Join Date: Mar 2013 Location: Australa Melbourne Posts: 878	Re: Model B Crankshaft The oil slinger is a different size and needs to be machined to fit the A block if it is off by just a few thou diameter, thickness and taper it will leak find a machine shop that has done this or you have you have it machined for a modern seal easier

07-11-2014, 09:02 AM	#11
Jim Brierley Senior Member Join Date: Jun 2010 Location: Temecula, CA Posts: 4,105	Re: Model B Crankshaft use ARP nuts, the 12-point kind and they clear the A pan with no mods needed.