'50 Coronet engine cracked.

[keithb7]

I'd like also to confirm if all these 25" long engines are drilled at the rear for the same bolt pattern? So in reality any bell housing for almost any flat 6 Mopar application could bolt up to the block?

Adaptor plates (various bell housings) for a basic 3 speed manual, powerflite, fluid drive, fluid torque drive trannys etc...Could all bolt up to the rear of the various bore/stroke blocks.

 

The main difference I have heard about is crankshaft rear flange. Various numbers of bolt holes and possible flange widths. Depending if you are bolting up a fluid drive or not. I have seen folks in this group have mentioned in various threads.

 

Here's how I take it....A 25" motor, 3 ⅜ or 3 7/16 bore, can be bored over quite a bit. For example a 3 ⅜ can be bored 0.060 over, then you have a stock standard bore 3 7/16 bore engine. Then a stock 3 7/16 bore can be bored yet another 0.060 over.  Is this correct?  These are big old blocks from the heyday of Detroit iron. 

 

It's very easy to find a rebuildable core. Ask the seller if you can take the head and oil pan off. Then go see it. Take a snap T gauge that covers upto  3 ½", and a digital vernier caliper.  Pick a couple of cylinders where the pistons are down. Measure the bore in the upper, middle and near the bottom of the cylinder. Side to side and front to back direction. Mark it all down on a piece of paper for each cylinder you choose to measure.  If there is a ridge at the top, measure it too. If there is no ridge, great. All the better. If there is a ridge present, it will generally tell you what the last bore was.  3 7/16 = 3.43750".  Add up from there. For example an engine that has been bored 0.030 over will measure  3.46750 at very top of the cylinder.  Look for cylinder wall scoring.  Consider how far it's been bored over already. Is there enough iron left bore out the scoring? A 0.060 over engine? Likely not.

 

Remove the oil pan. Pull a main and rod cap. Knowing what looks bad will reveal most all you need to know.  Scored crank journal bearing surfaces? Everything rusted up? Look up under bottom sides of pistons at cylinder walls. All rusted up?  Not great. 

 

I walk through these topics here: Ignore my math calculation. I had done the math on calculator with only 2 decimal places so the 3 digit rounded up. The measuring process here is the topic. How to learn more about the used engine you found.

 

 

Edited July 23, 2021 by keithb7

[kencombs]

3 hours ago, knuckleharley said:

Correct head or not,it's a 25 inch 251 engine.

I was just pointing out that the name on the head was exclusive to the Chrysler origin.  Lots of 251s, tractors, combines, cars etc, but only one had that on the head in my understanding.

[Dodgeb4ya]

There is also a possibility that 25" engine is a 265 too.

Pull the # 6 plug and measure.... the seller anyway.

[knuckleharley]

2 hours ago, librado65 said:

 

Do you know if it'll be interchangeable with my stock gryomatic transmission and rear axle? 

Not the first clue. I am sure someone here knows,though.

[knuckleharley]

1 hour ago, kencombs said:

I was just pointing out that the name on the head was exclusive to the Chrysler origin.  Lots of 251s, tractors, combines, cars etc, but only one had that on the head in my understanding.

My apologies. You are correct,and I may have misled him.

[knuckleharley]

1 hour ago, Dodgeb4ya said:

There is also a possibility that 25" engine is a 265 too.

Pull the # 6 plug and measure.... the seller anyway.

A Spitfire head will work on a 265?

 

BTW,I was thinking all the 265's were straight 8's,not 6's.

 

Shows how little I really know.

[keithb7]

The difference between a 251 and a 265 is  ¼” of piston travel. Also known as stroke. They share the same bore and pistons. Crank throw and connecting rod length is different. 
 

As mentioned by Dodgeb4ya. Pull the pipe plug over #6. Rotate then engine and measure stroke. 

A 251 engine is 4 ½” stroke. 265 engine is 4 ¾” stroke. 
 

 

[Dodgeb4ya]

Yes ...the 265's have the "SPITFIRE" head too.

On the Chrysler straight "8's ....  "SPITFIRE" is embossed into the 25" long metal spark plug wire loom on top of the cylinder head.

[Sniper]

Now that we've sort out the 25" head intricacies, I'd like to point out that no one has really answered the OP's question, will it work in his application?

 

I don't know or I'd answer.

 

 

[keithb7]

Nor can I answer 100%. Yet my gut tells me, pull the tranny. Ensure crankshaft ends are same on both engines. If so... Pull the blown engine.  Remove bell housing off spent engine.Install on replacement engine. Check other differences. Swap over any other parts necessary.  I’d wager the blocks are the same.  If not time to think about a plan B. 
 

I have no experience with that exact combination/scenario above. 
 

I bet that with our combined knowledge here, we can confirm it can be done. Or not. 

Edited July 24, 2021 by keithb7

[kencombs]

A couple of pieces of info:

 

 

 

1:  Many years ago I transplanted a 251 to a Dodge pickup while working for my Dad in his shop.  Just had to relocate the radiator forward to clear the fan.

 

The clutch housing bolted up fine.  And according to my old Hollander all the flathead sixes share the same pattern.

 

[knuckleharley]

2 hours ago, keithb7 said:

The difference between a 251 and a 265 is  ¼” of piston travel. Also known as stroke. They share the same bore and pistons. Crank throw and connecting rod length is different. 
 

As mentioned by Dodgeb4ya. Pull the pipe plug over #6. Rotate then engine and measure stroke. 

A 251 engine is 4 ½” stroke. 265 engine is 4 ¾” stroke. 
 

 

Ok,what are the same specs on a straight 8 flathead Mopar?

[knuckleharley]

2 hours ago, Dodgeb4ya said:

Yes ...the 265's have the "SPITFIRE" head too.

On the Chrysler straight "8's ....  "SPITFIRE" is embossed into the 25" long metal spark plug wire loom on top of the cylinder head.

Thanks!

[Dodgeb4ya]

11 minutes ago, knuckleharley said:

Ok,what are the same specs on a straight 8 flathead Mopar?

323 ci. Straight 8 bore is 3-1/4"

      .                      Stroke is 4-7/8" 

[keithb7]

4 ⅞” bore...Thats some wonderful torque!

[Dodgeb4ya]

32 minutes ago, keithb7 said:

4 ⅞” bore...Thats some wonderful torque!

Plenty and so smooth.

[RobertKB]

The original poster lives in Florida according to his profile so his car being a Dodge built in the US, I assume it will have the 23” engine. The Spitfire engine is the 25” engine. I don’t believe anyone has pointed out it’s not a straight forward bolt-in but will require some modification such as moving the radiator forward as well as the front engine mount. 

[knuckleharley]

12 hours ago, Sniper said:

Now that we've sort out the 25" head intricacies, I'd like to point out that no one has really answered the OP's question, will it work in his application?

 

I don't know or I'd answer.

 

 

Picky,picky,picky!?

[knuckleharley]

10 hours ago, Dodgeb4ya said:

323 ci. Straight 8 bore is 3-1/4"

      .                      Stroke is 4-7/8" 

Thanks! I THINK I used to know that,but chemo brain had me thinking the biggest flat Mopar engine was a 265.

[Dodgeb4ya]

Any 1946-54 230ci. Flathead Dodge engine will work.

Any 1954 up 230ci. Plymouth engine.

The engines must have the eight bolt crankshaft and must be 23" head length.

Manifolds, accessories and other pieces might have to be swapped from the original engine.

Industrial and marine....move on.

[Sniper]

5 minutes ago, Dodgeb4ya said:

Any 1946-54 230ci. Flathead Dodge engine will work.

Any 1954 up 230ci. Plymouth engine.

The engines must have the eight bolt crankshaft and must be 23" head length.

Manifolds, accessories and other pieces might have to be swapped from the original engine.

Industrial and marine....move on.

 

Thank you, now if I understand it and to be crystal clear, the 25" setup will NOT work for the OP, even with mods?

 

I know in my application, 51 Cambridge and a manual three speed, the radiator (moved forward) and motor mounts need addressed at the least.  Aside from incidentals like exhaust system and possibly wiring, throttle linkages, etc. 

[kencombs]

47 minutes ago, Sniper said:

 

Thank you, now if I understand it and to be crystal clear, the 25" setup will NOT work for the OP, even with mods?

 

I know in my application, 51 Cambridge and a manual three speed, the radiator (moved forward) and motor mounts need addressed at the least.  Aside from incidentals like exhaust system and possibly wiring, throttle linkages, etc. 

in my last post I left out a couple of things.  On the pickup I drilled new motor mount holes forward of the original.   Some cars may need a crossmember or oil pan mod.  You can find the late Don Coatney’s very good description of the process on this site. 

[Frank Gooz]

I have been reading and have a question I have a 1948 251. I bought a 265, Stamped C53. The 251 has a steel canister oil filter and the 265 like the engine shown on page one has a cast aluminum oil filter housing.

Is this a visible way to identify the two engines?

[Dodgeb4ya]

2 hours ago, Frank Gooz said:

I have been reading and have a question I have a 1948 251. I bought a 265, Stamped C53. The 251 has a steel canister oil filter and the 265 like the engine shown on page one has a cast aluminum oil filter housing.

Is this a visible way to identify the two engines?

Most only sure way is to measure stroke through the hex plug over cyl #6

Chrysler 251's started using the new style aluminum cannister in 1949 on up thru 1951.

Then in 52 the same cannister was used on the 265's thru 1954.

Now days so many flathead engines have been swapped modified whatever...

 Measure the stroke... the only way to be sure what displacement flathead engine you have.

 

[librado65]

21 hours ago, keithb7 said:

I'd like also to confirm if all these 25" long engines are drilled at the rear for the same bolt pattern? So in reality any bell housing for almost any flat 6 Mopar application could bolt up to the block?

Adaptor plates (various bell housings) for a basic 3 speed manual, powerflite, fluid drive, fluid torque drive trannys etc...Could all bolt up to the rear of the various bore/stroke blocks.

 

The main difference I have heard about is crankshaft rear flange. Various numbers of bolt holes and possible flange widths. Depending if you are bolting up a fluid drive or not. I have seen folks in this group have mentioned in various threads.

 

Here's how I take it....A 25" motor, 3 ⅜ or 3 7/16 bore, can be bored over quite a bit. For example a 3 ⅜ can be bored 0.060 over, then you have a stock standard bore 3 7/16 bore engine. Then a stock 3 7/16 bore can be bored yet another 0.060 over.  Is this correct?  These are big old blocks from the heyday of Detroit iron. 

 

It's very easy to find a rebuildable core. Ask the seller if you can take the head and oil pan off. Then go see it. Take a snap T gauge that covers upto  3 ½", and a digital vernier caliper.  Pick a couple of cylinders where the pistons are down. Measure the bore in the upper, middle and near the bottom of the cylinder. Side to side and front to back direction. Mark it all down on a piece of paper for each cylinder you choose to measure.  If there is a ridge at the top, measure it too. If there is no ridge, great. All the better. If there is a ridge present, it will generally tell you what the last bore was.  3 7/16 = 3.43750".  Add up from there. For example an engine that has been bored 0.030 over will measure  3.46750 at very top of the cylinder.  Look for cylinder wall scoring.  Consider how far it's been bored over already. Is there enough iron left bore out the scoring? A 0.060 over engine? Likely not.

 

Remove the oil pan. Pull a main and rod cap. Knowing what looks bad will reveal most all you need to know.  Scored crank journal bearing surfaces? Everything rusted up? Look up under bottom sides of pistons at cylinder walls. All rusted up?  Not great. 

 

I walk through these topics here: Ignore my math calculation. I had done the math on calculator with only 2 decimal places so the 3 digit rounded up. The measuring process here is the topic. How to learn more about the used engine you found.

 

 

 My favorite Mopar Youtube Celebrity just replied back to my post ??