Best 25” Flathead

[Don Coatney]

This is a photo of the factory dual/dual setup. I believe this was in a truck.

 

[HotRodTractor]

Does anyone know if the balance tube and carb speed governors were standard equipment on the factory dual carb setups? They appear to be missing from the one in Don's picture.

 

[Don Coatney]

1 hour ago, HotRodTractor said:

Does anyone know if the balance tube and carb speed governors were standard equipment on the factory dual carb setups? They appear to be missing from the one in Don's picture.

 

 

 

The difference may be my photo is a truck engine that runs at a full range of RPM's. Your photo is from a combine that  runs at constant RPM's. 

[HotRodTractor]

11 minutes ago, Don Coatney said:

 

The difference may be my photo is a truck engine that runs at a full range of RPM's. Your photo is from a combine that  runs at constant RPM's. 

 

This engine was out of a firetruck. The combine engine only has a single carb and has an RPM governor that runs off of a belt.

[Don Coatney]

Would the firetruck engine be governed to run a pump at a constant speed?

[HotRodTractor]

20 minutes ago, Don Coatney said:

Would the firetruck engine be governed to run a pump at a constant speed?

 

Maybe - but I always thought that the carb governors of this style limited vacuum in the carb - and in a way limited not only top speed, but acceleration as well. I never thought they controlled RPM specifically all that well, more of a load control - of course I could be all wet with this idea as I have never driven something with a carb governor. (And the governors in my picture has had the butterflies removed, so obviously someone thought they weren't necessary! lol).

[duesenberg1932]

I appreciate all the info.  My next trip to the junkyard i will keep my eyes peeled.  Im sure that somewhere in there is a 265, between combines, generators, forklifts, power wagons and 53-54 desotos/Chryslers.  They have an old car section at the back that will hopefully prove fruitful.  

[James_Douglas]

I picked up last year a 265 out of a combine. I took the head off last weekend. One always holds one breath as the head comes off. It is like a box of chocolate, you never know what you will get.

 

In this case. So far so good. The pistons are STD, the valves look good and there is almost no ridge. In fact the thing looks too good. The cooling holes show zero erosion on the bock and the head.  If the combine was used for a couple of weeks once a year and the water drained until the next year...then I can see why there may not be much wear.

 

It has the governor on it and the double pulley on the crankshaft as well as the updraft crab and the exhaust.  To bad that inner pulley cannot be used once a passenger car motor mount is on the block. The upside down mount allows for an inner pulley.

 

I will be pulling this thing apart and going through it as the next engine for the big Desoto.

 

I have know one person who did a restoration on an Airflow. They did some "not standard" stuff with the body on those. Engine changes may prove to be more of a challenge than you think. I would go find someone doing a restoration that has the body all apart and take some good photos and measurements before heading down that rabbit hole as it may be more work than one thinks.

 

James

[Ajgkirkwood]

https://www.kijiji.ca/v-classic-cars/london/1936-chrysler-imperial-airflow/1425058112?enableSearchNavigationFlag=true

 

[keithb7]

26 minutes ago, Ajgkirkwood said:

https://www.kijiji.ca/v-classic-cars/london/1936-chrysler-imperial-airflow/1425058112?enableSearchNavigationFlag=true

 

 

I’m drooling over that Airflow. Its located in Canada. I’m in Canada. Rare indeed. It’s needs a good caring owner. Wish it were closer. I’m in BC. A long ways from GTA area in Ontario.  The temptation is terrible. 

[greg g]

How does one quantify best?  HP, torque, parts availability,  best suited for the job at hand, most conversation about it's attributes?  If you go by HP it isn't the 251 or the 265 as they topped out at 116 door the DeSoto and 119 for the last Windsore six.  For peak HP from the automotive flathead six you need to go to the Dodge chart and look at the 135/138 HP units in the 57-59 model yeears.  If torque is your thing the top rating goes to the 54 Chrysler at 216, deSoto and Dodge were slightly arrear at 208.  Seems the argument could be made that the long block engines were slouches compared to the last year's of the Dodge automotive flatheads. In the long run the best on may be the one you can afford that is closest to you.  

[40desoto]

Did you just call the Spitfire motor a slouch!! ?. It spits fire!!

 

Im kidding Greg!  Thanks for the information

[Dodgeb4ya]

Engine Spec's on 1946-57 Dodge car and Dodge  truck engines...

[duesenberg1932]

Im looking for the best as far as what woll make the best reliable horsepower in a 25” block.  I know there isn’t as much aftermarket support when it comes to these engines, but i want to keep it in the same motor family that came factory with a desoto airflow.  I appreciate all the for sale ads, but im not ready to purchase yet.  Just doing homework at the moment.

thanks

[55 Fargo]

6 minutes ago, duesenberg1932 said:

Im looking for the best as far as what woll make the best reliable horsepower in a 25” block.  I know there isn’t as much aftermarket support when it comes to these engines, but i want to keep it in the same motor family that came factory with a desoto airflow.  I appreciate all the for sale ads, but im not ready to purchase yet.  Just doing homework at the moment.

thanks

Your ? has already been answered the 265.

Stock rated at 119 hp to 136hp.

Use a hotter cam tri carbs and headers and maybe what 150 to 160 or so.

It will be reliable HP as you stated.

[55 Fargo]

Here 265 powered 49 Plymouth.

 

[55 Fargo]

In fact go visit George Asche in Fertigs Pa.

He will educate you on this topic like no other.

 

[Ajgkirkwood]

17 minutes ago, duesenberg1932 said:

Im looking for the best as far as what woll make the best reliable horsepower in a 25” block.  I know there isn’t as much aftermarket support when it comes to these engines, but i want to keep it in the same motor family that came factory with a desoto airflow.  I appreciate all the for sale ads, but im not ready to purchase yet.  Just doing homework at the moment.

thanks

I dont have much experience on this, but this is only my opinion on what makes sense to me. I know the 265 motor is the biggest one and it's the one to have. However I think personally for a 25" block you would want to find a 218, 230 block or even better a 201 block. My reason for this is the stroke of the crank. The 265 has 4-3/4 stroke, the 251 is 4-1/2. Compared to a piston size of 3.4375, it's very much under square. I think the 201 had a stroke of 3-3/4. It was a 3.375 bore, however if u used a 3.4375 piston (like in a 251 or 265) you be much closer to a "square" engine, more so if you get oversized pistons. This will have less stress as you do highway speeds. With the common upgrades of milling the head (and deck too) dual carb and exhaust, and a regrind cam. It could really wake up and be a hot motor.

 

that being said, anyone have a crank from a 218 or 201 to sell?

[55 Fargo]

6 hours ago, Ajgkirkwood said:

I dont have much experience on this, but this is only my opinion on what makes sense to me. I know the 265 motor is the biggest one and it's the one to have. However I think personally for a 25" block you would want to find a 218, 230 block or even better a 201 block. My reason for this is the stroke of the crank. The 265 has 4-3/4 stroke, the 251 is 4-1/2. Compared to a piston size of 3.4375, it's very much under square. I think the 201 had a stroke of 3-3/4. It was a 3.375 bore, however if u used a 3.4375 piston (like in a 251 or 265) you be much closer to a "square" engine, more so if you get oversized pistons. This will have less stress as you do highway speeds. With the common upgrades of milling the head (and deck too) dual carb and exhaust, and a regrind cam. It could really wake up and be a hot motor.

 

that being said, anyone have a crank from a 218 or 201 to sell?

Yah right Kirkwood...lol

Tell this to George Asche. 

The 265 is king of torque and HP.

Whaddya think there gonna spin 4500 + RPM all day long down the freeway...huh

201 218 as a choice? Complete with offset rods.

You want power and highway cruising you go with a hopped up 230 or a 265.

Not 201s and 218s.. and you select appropriate gearing via your trans or diff to accommodate a sane RPM for highway cruising. 265 and 3.73 diff with an overdrive trans lots of go and enough gear reduction to cruise all day at 70 to 75 mph if needed.

Here check out this 265 revving no load to 5500 RPM, now it aint no driver car engine.

Edited April 6, 2019 by 55 Fargo

[55 Fargo]

 

[Ajgkirkwood]

I seen this stuff before. I know the rods go with the crank, I should have mentioned that. Again I'm  new to this myself however our motors have crazy high stroke compared tothe bores. That puts a lot of stress on the connecting rod, rings, crank and other moving parts due to how fast the piston is moving compared to the rpm, how much side load there is on the rod and what not from being so far out cause of the stroke. With the 265, it having the longest stroke and all 25 blocks are the same for the most part, it ends up having the shortest connecting rod, so we have a piston moving a lot faster per rpm compared to most engines because in that 1 rpm, it has to travel up and down 4-3/4 vs 3-3/4 that's on the 201. The shortest rod length means that rod is moving at more extreme angles then the 201 crank and rod would cause. Yes the stock 265 vs stock 218, it's the king of torque and horse power.... but by how much? Plus with the upgrades that are commonly done, that helps to equal a lot of things out. In 1954 the 230 was rated at 110hp the 265 was 119, however by 1959 the 230 was rated at 138. This could mean something or could mean nothing. 218, 230, 251 is easier to come by then the 265. 

[55 Fargo]

Listen Kirkwood dont compare a 201 to a 265 get real or the 230 for that matter with their offset rods.

There is no comparison.

If your pet theory was correct everyone in stock car racing to tractor pulling would have gone with 201 builds.

But of course they dont. The 230 by the end of the 50s with higher compression and even 2bbl carbs rated over 130hp.

The 230 is a stroker compared ro a 201.

Hopped up 201 is like stock 218, hopped up 218 like stock 230. 

A 250 is a good engine too and many a stock car used em, but a 265 with more stroke is a tougher beast.

Under square, square, oversquare these engines are not short stroke super high revvers 

But cammed correctly and built properly can rev way higher than what most guys need or want to subject their engine too constantly.

$hit man they pulled engines of assembly lines and ran them at 3600 RPM for 50 hours. You ever drive yours like that?

Edited April 6, 2019 by 55 Fargo

[kencombs]

Where people get confused with this stroke vs bore thing is comparing theoretical figures to practical use.  Yep, a short stroke high revving engine is theoretically capable of more HP per CUIN displacement.  Think the 302 chevy and 340 MOpar both made great HP north of 6K.  But, they can't compare to a 454/440 with the same sophistication of build.

 

Maybe one could build a .75 hp/ci 201/218 based high revving beast.  but that only  gets you to the base hp of a mildly built 265 turning a happy rpm.  And that is a weak maybe, as turning any flathead design faster always results in breathing issues.  90 deg turn to go up through the valve, another turn to head to the cylinder then another turn down to fill the cylinder just severely limits the potential. 

 

The torque developed is simply the pressure on the top of the piston acting against the lever arm of the crank.  Longer lever at the same pressure is more torque.  HP is how often than torque is exerted.  of course that is a way over simplified example.  Raise compression, add more fuel air, and turn it faster:  More HP.

 

But,  IMO that is why bigger is better.

[Dodgeb4ya]

On 3/29/2019 at 6:51 AM, HotRodTractor said:

Does anyone know if the balance tube and carb speed governors were standard equipment on the factory dual carb setups? They appear to be missing from the one in Don's picture.

 

I believe all the K series 2-1/2 tonners with the 265 twin carbs/exhaust came with dual King Seeley Handy governors and the balance tube.

But I think....as time went on the  hot rodders got hold of this truck set up and removed the tube and governors for more street performance.

I knew a 85 year old Dodge truck dealer in eastern Washington I would go see occasionally. He told me some of the over the road drivers of Dodge trucks would remove the governors for higher speeds/ quicker transport times... but sometimes engine damage would occur.

Stationary engines / fire trucks used different types of governors to maintain a steady RPM as on the power wagons with optional augers Etc.

Fire trucks would be the same to run the pumps not needing a high speed limit governor.

[Ajgkirkwood]

Sorry to the OP for my thoughts causing a stir. A 265 motor is the biggest ci, but might not be the best route unless money isn't an issue. From what I seen, finding replacement connecting rods might be an issue, same as a crank. A 251 is a lot easier I find to get those parts for. Myself though, if your looking for a block, look for ones with the full flow oil filtering, well from everything I reading it's a full flow. A lot of motors had no oil filtering or a bypass set up. These engines I'm sure are fine that way as they were made that way to begin with, but there are some with a bolt on full flow, m 265ci motor has it. The (2) 251 blocks I have apart do not have the mounting location for it .

Edited April 6, 2019 by Ajgkirkwood
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