Engine & Powertrain Compatibility Info Wanted

[keithb7]

A good friend of mine has a spare 1949 251 engine. This is the 25" long engine. Original bores. He has offered it to me at a "best friend" fantastic price.  I am interested in owning this engine as I "think" it may suit my long term needs.  Both my 1953 265 and my 1954 228 engines that are in service today display the same symptoms. Rear crank seals leak,  worn valve guides burning a little oil

while greared down holding back on a hill. Both burn little oil driving up the hill home. Compression is about the same in both engines hovering in the 100 psi range. Neither require a rebuild immediately. 

 

My 1953 Chrysler has the 265 engine. Same block and bore as the 251 if I recall, just a little longer stroke (1/4" longer the 265). Meaning different crank throw length I believe.  I assume possibly different con-rod length too.  I am not sure, but I assume the 265 may have a larger flywheel.  Not thinking I'd put the 251 in my Chrysler. But a spare 265 block is handy to have!

 

My 1938 Plymouth has had the engine replaced with a 25" 228 ci. I kind of like the idea of putting this 251 in my '38. Torque galore from the 251 in that little car, I would think.  I like the idea of building up the 251 on the side, while both of my cars are drivable. As time and money allow I can move along on the 251 rebuild. I am not interested in this 251 for higher top speeds or freeway travel. Nor driving 3.73 rear end. My 1938 has a 4.11 rear end.

 

Some unknowns and thoughts that I have: I was hoping a few folks here with more experience than me, could fill me in. I have a few books here to reference, including a 1949 shop manual for Canadian cars that all had the 25" long engines. Comparing the specs from all the 1949 25" engines, they all share so many vital parts and vital dimensions.

 

1938 has the 25" engine now. Would the 251 engine mounts, bolt right in?

 

My 1938 3-speed tranny, drive shaft and rear end, would they handle the extra torque of the 251 engine? I have no plans to drive it any harder than the 228 engine now.  Other than pulling the hill home in 3rd, the 251 should lug down pretty good and pull harder than my 228.

 

My 1938 Clutch diameter is 9 ¼". Optional 10" was available for taxis back in the day. I assume I'd should upgrade the clutch size. Due to increased engine HP and torque. Looking at a 1949 shop manual, I do see though that the C45  Windsor 251 had a 9 ¼" clutch too.

 

251 engine I suspect, should have a larger flywheel. The 251 engine bell housing was set up for use with an M6 tranny with fluid drive. I could swap over my 3 speed tranny bell housing, would it bolt up to the 251 block?

Would my 3 speed tranny pinion fit the pilot bushing in the back of the crank of the 251? I suspect I would likely need to source a flywheel drilled for use with a 10" clutch if I go that route.

 

The cooling system. Will my rad keep up with the increased HP (fuel burn and BTUs) from the 251? Not a big deal, but I could address that probably. 

 

Comparing specs:

Original 1938 201 Engine in my Plymouth was 82 hp 3600 rpm,

1949 251 engine: 116 HP at 3600 rpm. 208 bs ft torque at 1600 rpm

 

You thoughts are welcome.  Wouldn't a little P6 be a fun driver with a 251!  Any reservations? Thanks, 

 

Keith