alsfarms Posted March 12, 2019 Share Posted March 12, 2019 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 Link to comment Share on other sites More sharing options...
c49er Posted March 12, 2019 Share Posted March 12, 2019 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 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 12, 2019 Author Share Posted March 12, 2019 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 Link to comment Share on other sites More sharing options...
FLYER15015 Posted March 14, 2019 Share Posted March 14, 2019 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 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 14, 2019 Author Share Posted March 14, 2019 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 Link to comment Share on other sites More sharing options...
FLYER15015 Posted March 18, 2019 Share Posted March 18, 2019 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 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 18, 2019 Author Share Posted March 18, 2019 Good Idea Mike. Can someone post a few pictures of a Spitfire combustion chamber and also one of a typical Chrysler head? Al Link to comment Share on other sites More sharing options...
alsfarms Posted March 19, 2019 Author Share Posted March 19, 2019 Which Model of Chrysler used the Spitfire head? Al Link to comment Share on other sites More sharing options...
FLYER15015 Posted March 23, 2019 Share Posted March 23, 2019 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 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 25, 2019 Share Posted March 25, 2019 (edited) 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 March 25, 2019 by Rusty_OToole (see edit history) 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 25, 2019 Author Share Posted March 25, 2019 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 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 25, 2019 Share Posted March 25, 2019 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. 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 25, 2019 Author Share Posted March 25, 2019 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 Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 25, 2019 Share Posted March 25, 2019 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. 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 27, 2019 Author Share Posted March 27, 2019 hmmm, I would only change the rear end if I can keep the correct track, same lug pattern, improve gearing and have park brakes. That may be a tall order. Does sure a possible rear end exist? Al Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 27, 2019 Share Posted March 27, 2019 If you put in a 5 speed what do you plan on using for a handbrake? I can't tell you what rear axle to use. I would measure it for width and start junkyard shopping. At one time there were lots of rear drive Dodge Darts, Coronets etc but not anymore. Best shot might be certain Jeep Cherokee and Ford models that have the 5 bolt 4 1/2" bolt pattern. 1 Link to comment Share on other sites More sharing options...
alsfarms Posted March 28, 2019 Author Share Posted March 28, 2019 What is the reference for the Mid 30's Chrysler-Dodge-Plymouth and DeSoto forum? P-? I may pose the rear end question over there hoping someone has already been at the same place i am and will share some information. Al Link to comment Share on other sites More sharing options...
Rusty_OToole Posted March 28, 2019 Share Posted March 28, 2019 Are you thinking of the P15 D24 forum for postwar flathead Plymouths and Dodges?http://p15-d24.com/ Link to comment Share on other sites More sharing options...
alsfarms Posted March 28, 2019 Author Share Posted March 28, 2019 Hello Rusty, Yes, that is the website I was looking for. I will see what collective knowledge they have and maybe save me some time on a hunt for an alternate rear end that will match my needs. Regards, Al Link to comment Share on other sites More sharing options...
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