Thread: spitfire six

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alright i have a 39 chrysler royal with the sitfire flathead six and 3 speed on the tree i hve to do work to get the car on the road but the engine and tranny seem to be ok for now i am thinkin of turning it into the family hotrod but have read that the spitfire engine was somewhat of an option do i have some special "performance" six what can i expect out of this motor and is there any aftermarket boltons for it such as headers or carbs if so i may stay with the stock motor and dress it up to look good if i can squeeze a little out and not spend a fortune doin it if not i will drop a 350 or possibly a 327 and auto tranny in it just tryin to make my mind up and get some plans together thanks matt

Dose it have an aluminum head? Personally I'v only seen one. Might be a rare bird ya got there.

Dose it have an aluminum head? Personally I'v only seen one. Might be a rare bird ya got there.

Hi, What is the displacement of the engine? I recall that the '49 Chrysler was no slouch as a flathead straight six before they went to the Firepower hemi. I recently saw a picture of Smokey Yunick on one of the threads here tuning a Hudson flathead six, so maybe with dual carbs and a split exhaust (homemade) or a custom header and a slight head-shave you would have something that can move along and maintain the nostalgia of a "time machine". Still it depends on the state of the engine at present. If it needs a full rebuild you have to decide between chasing parts or a SBC replacement where parts are far more available. I guess I am trying to say that I still like restored cars in good shape as yours seems to be and if the original performance was "adequate" it is still an interesting car (with hydraulic brakes!). On the other hand if "adequate power" is 300 H.P. then it's time for a modern V8.

I have a "Motors Manual" that goes back to 1935 and it lists the '39 Royal-6 as 241.5 cu. in. with a C.R. of 6.50:1 (low!) and 100 brake H.P. at 3600 rpm. The '50 Royal-6 was rated at 250.6 cu. in., C.R. 7.00:1 and 116 brake H.P. at 3600 rpm. That gives some idea of what to expect with boring and raising C.R. without headers or dual carbs, but it looks like 150 H.P. might not be easy to achieve with only bolt-on improvements. Still I am reminded that my Chilton's manual for Corvettes shows only 165 H.P. for the '76 350 cu. in. (a bad year, but that's my engine before rebuilding).

Don Shillady
Retired Scientist/teen rodder

Skip the Chevy 327 or 350 and go with a Mopar 318/340. You can get a good one in a yard for less than a SBC rebuild. Keep the FI or run a carb and distributor. Dare to be different.

Your six banger isnt that bad of a motor, im running a destroked variant of it in my 53 right now and have no problems with it. There are aluminum high compression heads and dual carburetor intakes available used for it, check ebay. I came across a company that had dual exhaust for them, but there prices were insane. Still, these arent race motors, theyre better left stock or mildly warmed over. If you want more performance than just a daily driver then by all means find a decent small block mopar to put in her.

I have some goodies that would work on your 39,one is a factory dual carb intake and dual exhaust manifolds that came on 50s dodge trucks that used the chysler big six and a late 30s floor shift overdrive trans. I think I have a original distributor that has been converted to dual points,if you are interested let me know. Jeff

saw your post, ijust posted my mods to my flat head 6 under the flat head section of the form. my motor is the spitfrie 6
john