239 for 312 Engine swap

fordbedflat · #1 (**permalink**) 10-22-2009, 10:53 AM

Was advised to ask question here. I have a running 239 w/ 3spd overdrive out of a 55 effie and I want to put in a 57 wagon I recently purchased that has a worn out 312 and fordomatic.. How difficult would it be to swap in the 239 and leave the fordomatic and what would have to be changed? Money permitting I'll eventually put the 312 back in. Thanks for the replies.

HT32BSX115 · #2 (**permalink**) 10-22-2009, 02:06 PM

Howdy,

The 239 should bolt right up to the Fordomatic. I'm pretty sure you will have to use the starter and flexplate that is currently on the 312.

You can also go to http://www.y-blocksforever.com/forums/Forum3-1.aspx for a lot of info on this..

Cheers,

Rick

fordbedflat · #3 (**permalink**) 10-23-2009, 01:57 AM

Thanks for the info and website Rick!

Happy Motoring,
Brian

46yblock · #4 (**permalink**) 10-23-2009, 06:59 AM

After the 57 is running wth the 239, you will probably have more incentive to get the 312 rebuilt

.

fordbedflat · #5 (**permalink**) 11-01-2009, 07:13 PM

Quote:

Originally Posted by 46yblock

After the 57 is running wth the 239, you will probably have more incentive to get the 312 rebuilt

.

Your right! I pulled the 312 out last week and I'm going to rebuild it..For now the 239 will remain in the F-100.
Brian

46yblock · #6 (**permalink**) 11-02-2009, 06:49 AM

Quote:

Originally Posted by fordbedflat

Your right! I pulled the 312 out last week and I'm going to rebuild it..For now the 239 will remain in the F-100.
Brian

That sounds like a good plan. Hope the 312 is in fairly good shape. I've recently gained more respect for the 312s. For instance didnt know they have a narrower top compression ring, givng less power loss due to parasitic friction. Also John Mummert told me a 292 piston will result in skirt interference used with the 312 crank.

FYI, it is looking good for the use of an Eagle SBC 6.250 rod, with an offset ground 312 crank rod journal allowing the use of a 2.1 in. journal on the Eagle rod. All while using a 312 piston moded to take an SBC piston pin. The guys at y-blocksforever have been helping me wade through the process. Result would be a 312 with stroke increased from 3.44 to 3.50, and the ability to achieve zero deck (top of piston even with deck) without removal of a large portion of the block deck. Plus the Eagle rod is new and stronger than the original, at a cost equal to that of rebuilding the originals. I will know later today if the plan is a go.

Best of luck. Keep us updated.

Fifty4F100 · #7 (**permalink**) 11-15-2009, 07:03 AM

I know I'm late coming into this conversation. I think that just for 54, the 239 was made in Dearborn and Cleveland. The 2 were not interchangable. I don't know if the bellhousing mounts would be that different, but I would check.

And yes the 239 is a dog. Just over 100 HP that weighs within 10# of a 460!