Best 25” Flathead

[duesenberg1932]

Hi everyone,

I’ve been wandering the web looking for information on flathead mopar 6 cylinders, specifically the larger 25” block.  Is there any specific iteration of the 265 that is considered the best as far as durability and making horsepower is concerned?  Im having a bit of a hard time finding specific info on these engines.  Any help or a point in the right direction would be greatly appreciated.

Thanks

[40desoto]

1 hour ago, duesenberg1932 said:

Hi everyone,

I’ve been wandering the web looking for information on flathead mopar 6 cylinders, specifically the larger 25” block.  Is there any specific iteration of the 265 that is considered the best as far as durability and making horsepower is concerned?  Im having a bit of a hard time finding specific info on these engines.  Any help or a point in the right direction would be greatly appreciated.

Thanks

The Spitfire version of the 265 is the best. 

[duesenberg1932]

Awesome, thank you.  You wouldn’t happen to know what years and what model chryslers came with the 265 spitfire?  Are there any specific block marking/stampings that differentiates the 265 spitfire from 251s or earlier 242s beside the spitfire head?  I apologize for asking so many questions.  I will be looking to hunt one down in the near future and I just want to make sure i get what im looking for. 

Thanks

[captden29]

a motors manual will help to get that info. 265 was in passenger cars, Chrysler and desoto in 53 and 54. not sure where they were used after that,maybe trucks and military. the 265 is a 25" block. others are 23" block. these are not cheap anymore. I have a 54 Windsor that has the 265.strong runner and easy to work on. others on this site can give more info on identifying engines. not sure how well it will fit the desoto airflow you want.  good luck,  capt den

[Don Coatney]

I believe the "SPITFIRE" head was Chrysler only (not Desoto) and I believe there is no performance difference in the Spitfire head and the non spitfire head. The spitfire head is just prettier. 

 

[duesenberg1932]

Capt den,

From what I could find, the desoto airflow had a 25” 242ci from the factory.  I read that just about all of the 25” should bolt up, not taking into account the transmission bolt pattern.  I very well could be wrong, but that’s what I could find.

thanks

[40desoto]

16 hours ago, 40desoto said:

The Spitfire version of the 265 is the best. 

My apologies.  I was being a bit sarcastic about the Spitfire version being the best.

as far as I understand the spitfire raised lettering on the head is just for asthetics.

i believe the 265 is the largest of the 25” flathead six motors that came in Desotos and Chryslers and other Canadian Dodge and Plymouth.

im assuming the later model wngines are better due to the engineering enhancements.  I have a running 251 25” motor laying around but not sure if it will fit the Airflow. Most likely if there is a didference it would be in the bellhousing transmission differences. 

What do you have in it now? Send us an engine stamped number

[40desoto]

4 hours ago, Don Coatney said:

I believe the "SPITFIRE" head was Chrysler only (not Desoto) and I believe there is no performance difference in the Spitfire head and the non spitfire head. The spitfire head is just prettier. 

 

What about the Spitsfire head?

[duesenberg1932]

See the funny thing is that I don’t have an airflow yet.  Im gathering info based on the direction i want to take the build when im in a position to buy one.

[Plymouthy Adams]

hope you not quite like a guy I knew a guy who bought a Corvette jacket, then a BMW jacket and on to Porsche...he got really mad when I asked him what is the next car he is NOT going to buy....turns out he never even kicked a tire at the dealerships…

 

but yes...mucho credit for checking availability before locking into a car that has no support.....

[Don Coatney]

18 minutes ago, 40desoto said:

What about the Spitsfire head?

 

You need to talk to Reg Evans about the spitsfire head.

[40desoto]

29 minutes ago, duesenberg1932 said:

See the funny thing is that I don’t have an airflow yet.  Im gathering info based on the direction i want to take the build when im in a position to buy one.

I’d recommend you buy one that is complete and motor in it.

if your spending that much on restoring an Airflow might as well get an engine rebuilt.

Airflow parts are rare.  https://www.ebay.com/i/143072891521?chn=ps&ul_ref=https%3A%2F%2Frover.ebay.com%2Frover%2F1%2F711-117182-37290-0%2F2%3Fmpre%3Dhttps%253A%252F%252Fwww.ebay.com%252Fi%252F143072891521%253Fchn%253Dps%26itemid%3D143072891521%26targetid%3D484268501929%26device%3Dm%26adtype%3Dpla%26googleloc%3D9031119%26poi%3D%26campaignid%3D1497794128%26adgroupid%3D56281259485%26rlsatarget%3Dpla-484268501929%26abcId%3D1139466%26merchantid%3D6296724%26gclid%3DEAIaIQobChMI087no9Kl4QIVGx-tBh3-mQODEAQYASABEgKnLfD_BwE%26ul_ref%3Dhttps%25253A%25252F%25252Frover.ebay.com%25252Frover%25252F0%25252F0%25252F99%25253Floc%25253Dhttps%2525253A%2525252F%2525252Frover.ebay.com%2525252Frover%2525252F1%2525252F711-117182-37290-0%2525252F2%2525253Fmpre%2525253Dhttps%252525253A%252525252F%252525252Fwww.ebay.com%252525252Fi%252525252F143072891521%252525253Fchn%252525253Dps%25252526itemid%2525253D143072891521%25252526targetid%2525253D484268501929%25252526device%2525253Dm%25252526adtype%2525253Dpla%25252526googleloc%2525253D9031119%25252526poi%2525253D%25252526campaignid%2525253D1497794128%25252526adgroupid%2525253D56281259485%25252526rlsatarget%2525253Dpla-484268501929%25252526abcId%2525253D1139466%25252526merchantid%2525253D6296724%25252526gclid%2525253DEAIaIQobChMI087no9Kl4QIVGx-tBh3-mQODEAQYASABEgKnLfD_BwE%252526rvr_id%25253D0%252526rvr_ts%25253Dc5eccf271690a9cb9a05ef03fffea25e%26srcrot%3D711-117182-37290-0%26rvr_id%3D1914059705375%26rvr_ts%3Dc5eccfad1690a9ca12d11ab8ffff30f2

Edited March 28, 2019 by 40desoto
Updated to edit

[duesenberg1932]

I did see that one on ebay.  Its like a splinter in my brain lol.  If i had the extra cash right now it would be mine.  Saving for my first house is priority #1 at the moment. Unfortunately, yes airflow parts are quite rare, but im not concerned about 100% originality.  As long as it period correct, im cool with that.  Im looking to make sort of like a factory style high performance special. Supercharged  265, winters quick change rear end, tube shocks, heavy duty springs....I figured I would start with the the best engine in the flathead 6 mopar family for my future project.

[Don Coatney]

24 minutes ago, duesenberg1932 said:

I did see that one on ebay.  Its like a splinter in my brain lol.  If i had the extra cash right now it would be mine.  Saving for my first house is priority #1 at the moment. Unfortunately, yes airflow parts are quite rare, but im not concerned about 100% originality.  As long as it period correct, im cool with that.  Im looking to make sort of like a factory style high performance special. Supercharged  265, winters quick change rear end, tube shocks, heavy duty springs....I figured I would start with the the best engine in the flathead 6 mopar family for my future project.

 

[maok]

1 hour ago, duesenberg1932 said:

I did see that one on ebay.  Its like a splinter in my brain lol.  If i had the extra cash right now it would be mine.  Saving for my first house is priority #1 at the moment. Unfortunately, yes airflow parts are quite rare, but im not concerned about 100% originality.  As long as it period correct, im cool with that.  Im looking to make sort of like a factory style high performance special. Supercharged  265, winters quick change rear end, tube shocks, heavy duty springs....I figured I would start with the the best engine in the flathead 6 mopar family for my future project.

 

So you are going to 'de-value'  a unique model in time and history? Why not do that to something more common like a Dodge or Plymouth of the period. IMHO.

Edited March 28, 2019 by maok

[Plymouthy Adams]

most of the time the very unique thing about this hobby and what sets one apart from another is being a shade different than the next guy....sometimes you can do that with paint but don't count on it.....I also think it is devaluating a car that already suffers a very small footprint at any gathering....but I will give him credit for sticking with a mopar engine in his plans...last thing I would want to do is park my car next to one just like mine....let the '32 cookie cutter folks have that glory, don't care much for the billet blobs....and for the record, we have one of these cars by another owner undergowing a slight twist right now....

[duesenberg1932]

I can appreciate everyone’s opinion, but i’m not building a car for you guys....Im building a car for me.  To me, the other mopars of the era are cool, but they don’t reel me in like the airflow does.  America’s version of the beautiful teardrop coupes from Europe.  I don’t plan on making a street rod...like i said, im look to make a factory style special of sorts.  Improved power, handling and braking without using post 1950’s technology.  Im not looking to invest my money in a car.  Imnot worried about potential value when im done building it.  I am looking to build a car that i have been dreaming about for years. So, any other things I should be looking for in my 265 hunt?  Anyone have any info on the availability of these motors in trucks?

[Plymouthy Adams]

wiki had a list of applications for the 265 and the difference in car, truck and industrial applications...sorry I was not researching this for myself or anyone else...but I know it is out there...was of no interest to me to earmark the page.

[HotRodTractor]

For what its worth - I picked up a very low hour late production Industrial 265 that just happened to be wrapped in an Oliver combine. I paid $100 for the combine 15ish years ago with 300 some odd hours on it. Pulled the engine, scrapped the combine. A cam swap and it should be up to the specs needed - if you go the industrial route. Spitfire heads are plentiful if you want to go that route - or pick up an aftermarket finned aluminum head. Dual carbs and exhaust can be had as factory parts as well.

 

FWIW - I'm kinda doing the same thing except with a PilotHouse pickup - basically making it a "factory" hot rod with a 265 factory dual carbs and dual exhaust, Spitfire head, etc...  Took me a long time to pull together the base parts for the project. Now comes all the work. lol

 

Some good motivation has been a P15 that I picked up from Don with a drivetrain pretty similar to what I was already working towards. I only have about 50 miles on it, but its definitely encouraging me to get rolling on the pickup once I finish a few fixes to make that a DD capable ride (wiring, minor fuel issues, typical old car stuff). 

[Dodgeb4ya]

Truck flat heads in 1-1/2 ton on up get worked real hard. Those being 236, 251 and the 265 engines.

A truck 2-1/2 ton 265 probably has seen a real hard life.... pedal to the metal most of the time.

Chrysler cars with the 265 not so.

[Reg Evans]

5 hours ago, Don Coatney said:

 

You need to talk to Reg Evans about the spitsfire head.

 

A picture's worth a thousand words.  Presenting the uber rare 23" 230 spitSfire

 

[duesenberg1932]

That sounds like a pretty cool project.  I have a junkyard that I frequent that does have some farm equipment.  Do the industrial engines interchange with the automotive engines? If so, that definitely could be an option.  I was unable to find said wiki page for make/model cross reference for industrial/truck applications.  When i’m poking around the junkyard, is there a way to tell a mopar flathead apart from other flathead sixes when looking at things like combines, forklifts and generators?  As far as truck flatheads, they probably did see a pretty hard life, but the trucks seem to be a little more common at least around these parts (eastern pa).  If they are rebuildable, I'm game.

[HotRodTractor]

34 minutes ago, duesenberg1932 said:

That sounds like a pretty cool project.  I have a junkyard that I frequent that does have some farm equipment.  Do the industrial engines interchange with the automotive engines? If so, that definitely could be an option.  I was unable to find said wiki page for make/model cross reference for industrial/truck applications.  When i’m poking around the junkyard, is there a way to tell a mopar flathead apart from other flathead sixes when looking at things like combines, forklifts and generators?  As far as truck flatheads, they probably did see a pretty hard life, but the trucks seem to be a little more common at least around these parts (eastern pa).  If they are rebuildable, I'm game.

 

Not all inclusive - but camshaft of an industrial needs swapped out, distributors usually lack vacuum advance, and sometimes the intake/exhaust manifold setup isn't conducive to a car/truck (vertical exhaust, updraft carb, that kind of thing). Beyond that - they are pretty interchangeable. They installed them in pretty much everything. I've seen them in combines, tractors, generators, air compressors, loaders, forklifts, airport tugs, I almost bought a crazy all wheel drive skid steer tractor type thing at an auction years ago because it had one in it, but the semi was already full and its a long road to drive it home from Colorado. And they made them for industrial purposes up into the 1970s.

[keithb7]

Interesting info in my Motors Manual. 

 

251 engine bore 3 7/16”,  stroke 4 1/2”. HP 116.  Torque  208 @ 1600.  Compression 7:1. 

 

265 engine bore 3 7/16”. Stroke 4 3/4”.  HP 119. Torque 218 @ 1600. 

Compression 7:1. 

 

Seems to me these engines are quite close. The 265 got an extra 1/“4 longer stroke. 

 

Interesting to find no 265 engine option listed in the Desoto section of my Motors manual. I see 236.6 and 250.6 L6 engine options there. Plymouth 217.8 and 230 L6 options. Dodge 230.2 L6 is only L6 option. I assume this is for USA models. My 1953 Chrysler has the 265 L6. I do like it. Supercharge it? I never would. Not based on what I see in there.  I guess you'd plan to do a lot more parts upgrades to support a Supercharger. Kinda makes me cringe a little. To each their own.

 

Edited March 29, 2019 by keithb7

[HotRodTractor]

7 hours ago, keithb7 said:

Interesting info in my Motors Manual. 

 

251 engine bore 3 7/16”,  stroke 4 1/2”. HP 116.  Torque  208 @ 1600.  Compression 7:1. 

 

265 engine bore 3 7/16”. Stroke 4 3/4”.  HP 119. Torque 218 @ 1600. 

Compression 7:1. 

 

Seems to me these engines are quite close. The 265 got an extra 1/“4 longer stroke. 

 

Interesting to find no 265 engine option listed in the Desoto section of my Motors manual. I see 236.6 and 250.6 L6 engine options there. Plymouth 217.8 and 230 L6 options. Dodge 230.2 L6 is only L6 option. I assume this is for USA models. My 1953 Chrysler has the 265 L6. I do like it. Supercharge it? I never would. Not based on what I see in there.  I guess you'd plan to do a lot more parts upgrades to support a Supercharger. Kinda makes me cringe a little. To each their own.

 

 

I don't have the info in front of me, so I am going off of memory - but I believe the 265ci engine was advertised at 136hp with factory dual carbs and dual exhaust in 1954 (the same year the Hemi was introduced at 133hp). This would have been for larger trucks 2-1/2T and up.

 

Edited March 29, 2019 by HotRodTractor