The Chrysler 265 & The M37

[SasquatchSanta]

I'm starting this thread so it will hopefully be a gathering point for information on the 265 Chrysler flathead.

I am NOT an authority on the 265 however, over the years, I've done some research on the 265 that could make it easier for others that go the 265 route. Corrections are welcome.

The 265, especially in a Canadian M37 offers an unnoticeable modification that will make the M37 into a vehicle that will easily pull 489 gears. Add a cam, zero balance and a few other internal goodies and you've got a 3,200 RPM, 65 MPH truck.

I'm told that installing the long block 265 (or 251) in an American M37 requires a Canadian radiator and special canadian front motor mount. Having said this, I'm also told the standard American radiator can be used by mounting it on the mounting housings forward mounting brackets.

Note: If anyone has any info on the specifics of the required front motor mount please advise.

I'm told the 251 and 265 flywheel has a different number of teeth than the 230 therefore care must be taken when matching starters. The 230, 251 and 265 flywheels all interchange.

The difference between the 251 and 265 is the crank, rods and cam. The 265 uses standard 251 pistons.

The 251 and 265 long block (25-1/4" long) engines use the same block though I'm told the original 265 was equipped with a full gally oil system.

My research indicates the following block numbers used exclusively for the 265:
(I assume these blocks had the full oil gallery) (This list needs to be verified)
1400929
1402429
1551229
870744
1402529
1115829
The following blocks were listed for both the 265 and 251:
(I do not know why these blocks are different. Perhaps they were for engines built before the release of the 265)
1400229
1138129
1115829

The 265 chrakshaft number is: 1400188

The following trucks offered the 265 engine:

1957, 58, 59 & 60 W500
1957, 58 & 59 D600
1957, 58, 59 & 60 D500

The big disagvantage of the 265 is the availability of crank, cam, and rods.

On another note ... For personal reasons, I've always wanted to build a 265 using a Spirfire head. The Spitfire head had "Spirfire" cast into the top and was used on the 251 Chrysler and Desoto engines. If anyone knows if there are any benefits associated with the Spitifre head please advise.

 

[acetomatoco]

Don't forget to install the disc brake kit at the same time... cuz if you think you wanna go 65 ya gotta be able to stop... ACE

 

[Superdave]

There was a good discussion and some pictures regarding the installation difference between the Canadian 251 and the US 230 M37 on the Powerwagon Advertiser website. I hope that I can post this here.

http://www.powerwagonadvertiser.com/forums/showthread.php?t=2514&highlight=mounts

 

[Jones]

You should check this out before getting too far into things but if memory serves me, when we did an engine swap into my M37 the stamped front motor mount saddle on the block just needed to be removed and turned around so the "feet" pointed backwards and that solved the front mount problem.
A critical thing with the flat head sixes is that there is a "car" and a "truck" engine. We put my engine together out of several donors and found that the rods are different lengths and the longer rods make the pistons hit the head if assembled on a crank with more stroke. If you're unsure, turn the engine over before putting the head on... I guarantee it'll save you grief in the long run. We didn't notice and were able to get the head on 'cause none of the pistons were at top dead center, then we proceeded to drag the truck for several blocks, sliding the tires in an effort to get it to turn over. Ahh, to be young and inexperienced... and dumb.
Lastly; there's this thing called a "water distribution tube" that slides/hides in the block behind the water pump and is there to make sure the rear cylinders get sufficient cooling water circulated past them. Since the tubes are sheet-metal and sometimes rust out, remember to be sure you've removed ALL of the old tube and replace it with a fresh one.

 

[citizensoldier]

very interesting Sas.. I am on the hunt for parts now.. Keep us posted on your progress I am very interested in this for my truck...

 

[citizensoldier]

Maybe you have seen this, but I found it to be a good read and it mentions the Spitfire engine..
http://www.allpar.com/mopar/flat.html

 

[citizensoldier]

Hey Sas??

Well how are things going? Any updates on the 265? I am really wanting to know how it works out. I have 2-251's to rebuild and would like to maybe try this 265 if I can come up with the parts and get the know how from you.
Lane

 

[SasquatchSanta]

RE: Hey Sas??

Yesterday I finished rebuilding and installing a spare front axle assembly in "The Woogie" --- a 1952 M37 that I've had for 14 years.

The main purpose in rebuilding the assembly was to instal a set of 489 gears and a locker. I had installed 489s and a locker in the rear last year and thought it was time to spec out the front assembly before I forgot and slipped the transfer case in 4WD. I don't think 489s in the rear and 583s in the front would socialize well.

Anyway, with the 489s finally installed front and rear it's time to move on to the 265 project.

I was thumbing through some old motor manuals the other day and was surprised to see that the 230 and 251 Chrysler flathead engines (I couldn't find anything on the 265) are rated for either 3,500 or 3,600 RPM (I can't remember which). Anyway, that's a whole heck of a lot faster than the 2,500 red-line I've always adhered to! Could it be that all the manuals overstated the safe operating RPM?

Because the 265 has a 1/4" longer stroke than the 251 I've been having second thoughts about installing a special high preformance cam. Like I said earlier, I couldn't find specs on a 265 but if they were rated to rev (against better judgment) over 2,500 RPM why would you need a high speed (high performance) cam?

I'm quickly getting in over my head here so correct me if you feel I'm off base but logic says if I zero-balance the engine, so it will stay together, plus nitrite the crank and cam and install heavy duty valve springs there will be very little advantage to changing the cam. I would like to spin the 265 at around 3,000 RPM. If the stock truck cam is capable of spinning the engine at 3,600 it seems changing the cam would be a waste of money, and possibly torque. ???

If anyone has a torque chart on a 265 it would be interesting to see what it sez. It may be that the stock cam is hard to improve on.

Opinions are welcome.

 

[Ferroequinologist]

Resurrecting an oldy. Did you ever get anywhere? I am on the hunt for a 251 or 265 to put in my custom build, going to need the extra power. (secret project- for now)

Been on the hunt for one or the other for about a year now. If I can at least find a 251 block, I can build a 265.

Just doing a bunch of searching and saw your thread.

 

[54M37]

The CDN trucks also have a hood that is slightly different so the safety catch latches properly. The rod bolts for the 265 has a very unique flattened head because of the small rotational clearance and are very scarce. I have a 265 that has been balanced with split exhaust and an Edmonds aluminum high compression head in my CDN 152 and it has a great deal more torque and power than my M-37 with the 230. I have Spitfire heads and dual carb intakes, split exhaust manifolds and several long blocks and 265 cranks I would like to part with. If any one is interested in them or has any questions my e-mail is DodgeM37@aol.com.