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1937 DeSoto Engine Question

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I have a 1937 DeSoto Coupe project.  I have acquired a later series Chrysler 265 to rebuild and install in the car.  My question, of those with more knowledge than I is this;  Will installing a Spitfire head, on the rebuilt 265 help or hurt performance?  Help is appreciated.

Al

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A  265  out of a 1952-54 Chrysler should already have a "Spitfire" head.

If it was a 1953 up Dodge 2-1/2 ton truck engine 265 it would not have the "Spitfire" head.... just a plain head. 

Compression ratio for the car 265 ..... 7.0                               

  "                       "   for the truck 265 ......6.8

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c49er, Thanks for your response.  I have been doing some deep thinking on my question and now have a second and follow up question on this same question.  My 1937 DeSoto currently has the factory original engine still in place.  The 265 engine I have purchased is a later version of the 265 and is out of a fork lift, so it is an industrial version.  I am now wondering if I were to use the head off the 1937 DeSoto engine if it may actually be better for compression that using the Spitfire head.  I will be rebuilding the 265 and using all the pieces from the '37 DeSoto engine to assemble the 265 for automobile use.  Anyone with experience here please share your thoughts.

Al

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If you want to boost the performance, could you not just "plane" the original head ?

That way you would know it is "true".

 

Mike in Colorado

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Mike,  Shaving the head is sure a very real possibility.  I am wondering if the Spitfire head may have a better combustion chamber.  I have never had a Spitfire head in hand to compare.

Al

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On ‎3‎/‎14‎/‎2019 at 3:00 PM, alsfarms said:

Mike,  Shaving the head is sure a very real possibility.  I am wondering if the Spitfire head may have a better combustion chamber.  I have never had a Spitfire head in hand to compare.

Al

Lets ask the community to post some pictures  of the underside to check the similarity / differences and then you could do a modification to the chamber if you want.

One thing you need to watch is the water jacket hole pattern. They need to be exactly match your block, or you will have overheating issues.

 

Mike in Colorado

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Good Idea Mike.  Can someone post a few pictures of a Spitfire combustion chamber and also one of a typical Chrysler head?

Al

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Al,

There is a you tube video of a guy milling the head of a '35 Chrysler, after doing a bunch of welding on it but it sure looks to be aluminum.

 

Check it out.

 

Mike

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I believe Chrysler used the Spitfire name for their engines from 1946 to 1954 and the name Spitfire was cast into the head. These had 6.6:1 compression, rising to 7:1 starting with the 1949 models. The same engine was used up to 1968 in trucks, and 1972 as industrial and marine power plants. These later ones may have had higher compression.

 

Your 1937 engine should have a smaller combustion chamber than the later engine. Even though it only had 6:1 compression the engine was only 228 cu in. It would give higher compression on the larger engine.

 

Probably the highest compression stock head would be off a Canadian Dodge or Plymouth 1957 - 1959. They used a smaller version of the same engine and had the highest compression of any Chrysler built flathead six.

 

You can easily examine and compare the 1937 and Spitfire heads. If you want to be really scientific you could measure the different combustion chambers. This requires a plexiglass or glass plate with a hole to cover the combustion chamber and a burrette to fill it with a measured amount of oil.

 

If you want to go nuts you could buy an Edgy aluminum cylinder head, they are nice but I don't think they are worth $1400.

http://www.moparmontana.com/store/c3/CYLINDER_HEADS.html

Edited by Rusty_OToole (see edit history)
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Hello Rusty,

Thanks for your thoughts.  I was thinking what you suggested which is to use the 1937 DeSoto head on the later series Chrysler 265 engine and end up with an increase of compression (performance) that way.  I really do not care about a tire spinning race car but by using the 265 I should have enough twist that the car would behave nicer in our modern driving conditions.

Al

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I would check combustion chamber volume and also valve clearance, the older engine may have smaller valves, I don't know for sure. If you mill the head round off any sharp edges that may create hot spots which can lead to preignition. The limit for flathead compression is around 8:1, go higher and you cut off breathing by making the chamber too small. Flatheads don't have a great combustion chamber shape and will not tolerate as high compression as an OHV engine anyway.

 

There are other things you can do and still keep a stock appearance. Like adapting a larger carburetor, possibly one off a Ford 300 cu in truck six. And if you have a new exhaust made, make it 1/2" larger in diameter than stock. You might also get a reground cam.

 

The object is not so much more speed, as the power or torque to pull a higher rear axle ratio. This will allow smoother cruising at highway speeds. Or, an overdrive will give the best of both. Low speed torque and smooth high speed running.

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Yes,  I do agree, no race car in the future for the DeSoto coupe.  Just a nice driver.  I have a spare Borg-Warner T-5 hiding in the back of my shop that I am considering a conversion that would give me an overdrive and an extra gear.  When the time comes, I will explore that option.

Al

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The big flathead six may surprise you.  The long stroke and high torque make driving easy, and have a lot of punch in the lower speed ranges where most driving is done. In other words, everyday driving performance is better than the HP numbers suggest. The 5 speed is a good idea, but you will have to change the rear axle or somehow arrange a hand brake, it is on the transmission of the DeSoto.

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