spitfire head for a desoto 230 engine

[TodFitch]

I just got back in town from vacation in the stix...let me see if I can run the head over to the P.O. tomorrow (if you still need it) to verify shipping.  I apologize for any problems!

Please use the PM facility when doing a one-to-one conversation. It will keep the thread cleaner.

[janan5243]

I did the first one posted cold & then realized it should be done with engine warm. No oil first or second test, I guess that test would tell me about valves & rings. If & when I change head I could hand lap the valves & seats.

[janan5243]

I started a post about a spitfire head to use on my Desoto 237. Got a lot of good replies. Wanted to know about milling head to increase CR.

Have a possibility of 2 heads. One from a 251 & one from a Spitfire which I believe is a 265. George Asche told me that using those heads would be going backwards. I guess he meant that the combustion chamber in the head was larger than my stock head. Can anyone tell me where to find out those specs & if those heads could be safely milled enough to increase CR without creating valve clearance problems? Can you tell from the casting numbers what size engine a head was for? Actually, I have a possibility of three heads. The third from Asche, quite reasonable, already milled, but he wasn't positive it would be from a 237.

Edited September 4, 2014 by janan5243

[Don Coatney]

Not sure why you started a new thread as most of your questions were answered on this thread linked below.

 

http://p15-d24.com/topic/36430-spitfire-head-for-a-desoto-230-engine/

 

Perhaps a moderator will combine these two threads to keep all the answers in one location.

[Plymouthy Adams]

unfortunately there is no exact way to guess at the head volume without CCing the head...formulas for this include such thing as piston below surface measurements and head gasket squish that you have to know to get a dead on volume number...not sure if you could find this on search..so so long ago..

Edited September 4, 2014 by Plymouthy Adams

[janan5243]

I started a new thread because I wasn't sure anybody went back to old threads. Be that as it may, it was combined. All questions were not answered because of many factors in determining CR. Thought there may be someplace with tech specs to help. I guess not. I guess, if you plugged sparkplug hole, you could fill chamber in head with water & measure volume, then convert that to cc's. If you had access to all three heads you could compile data. Kind of basic but I can't figure any other way to get dimensions. Maybe if you had a good CAD program & knew how to use it, you could get answers.

Edited September 4, 2014 by janan5243

[Plymouthy Adams]

If you have an old thread , any new entry will reactivate it and will bring it back to the forefront.  if someone searching the forum for pertinent data that would be found in your thread it will be available to read also.

 

CCing the head is usually done with clay..head chamber filled with clay and shaved flush...compressed gasket fill and shaved flush..top of piston to top of block filled and shaved flush...then the clay is removed and combined...then start with say 300 CC  of water in 500 CC graduated cylinder. Drop in the clay and read the newly displaced water level subtract your reference 300 CC and you have the effective head volume..as this is in CC and not CI you will  then convert to CI by multiplying time .061  

 

there are many arguments of how to get CR..some say it is VBDC + head volume divided by VTDC but this will never get you the official specs as reported by ma mopar in the older days and original specs...you will in fact get an effective 1.0 CR error in either direction...they used raw data it seems...VBDC divided by VTDC which is your effective head chamber only..do the math using Mopar raw posted data and bore stroke...and prove this right..it also will give you the very basic figure for the stock head chamber volume..I will not argue beyond what is written by Ma Mopar in the day to that of what folks are effectively doing today..the number just WILL NOT match..I only know what was used to arrive at their posted CR..

[Dave72dt]

CC's of the head gasket and piston to deck are only relevant when calculating compression ration. Comparing the CC's of the various heads may be the basic info needed. There may be some differences in chamber design that may or may not come into play if volumes are comparative. Then again, over the years who really knows if and how much a particular head may have been planed previously.

[Plymouthy Adams]

Yes...I explained them each separately  I continued with the CR after finding head volume as it is usually this that is the driving factor behind CCing a head and you really need these factors added in so to get the right ratio,.albeit a tad of difference..it could be the difference of 87 verse higher grade gas..just an FYI if this is that critical you can displace each item one at a time and read each value..

[janan5243]

Thanks Plymouthy & Dave. That's great info. I'm trying to figure if there is a difference in the head combustion chamber volume between the three engine sizes & if a head from a larger CC engine could be machined enough to effectively increase my CR. It sounds like the easiest & cheapest way would be to try & find a head from a Canadian Plymouth or Dodge 201 or 218, which I've read , were all 25" blocks. And again, how do you tell which head is which. From casting #s & where to find what # went to what size motor????

Edited September 5, 2014 by janan5243

[Don Coatney]

Thanks Plymouthy & Dave. That's great info. I'm trying to figure if there is a difference in the head combustion chamber volume between the three engine sizes & if a head from a larger CC engine could be machined enough to effectively increase my CR. It sounds like the easiest & cheapest way would be to try & find a head from a Canadian Plymouth or Dodge 201 or 218. And again, how do you tell which head is which. From casting #s & where to find what # went to what size motor?

What is your end objective? Are you looking to build a full race engine that spins at close to 6000 RPM's? A stop light to stop light drag racer? Or a dependable street engine with a bit more oomph and a lot of coolness?

 

Doing all these CC measurements will tell you just what your compression ratio is so you can get that last dollop of horse power from your engine. But when it is all said and done you still have a souped up flathead 6 cylinder engine that is no longer very dependable and produces something well under 200 HP.  

 

If you are looking to build a dependable cammed up multi carbureted dual exhaust engine that will get a lot of OH's and ahs when the hood is raised there is not a need to go through the CC process to know exactly what your compression ratio is. Mill your existing head 40-50 thousands, add a lumpy cam, dual everything, and drive it like you are hauling a load of moonshine.

[Plymouthy Adams]

all good questions that were brought up long long time ago and I tried to enlist the help of the forum at large with casting numbers from their respective engines and if or if not hey knew the history on shaved or not and actual thickness of the head casting itself...I got naught

[janan5243]

Don; as I stated in the beginning of this post, I'm not interested in 1/4 mile speed or times. I, simply looking to achieve your third choice. As far as wanting to know if there are differences in heads, according to the flathead Guru, George Asche, using a head from a larger displacement engine would not achieve CR increase. I'd like to keep my head as a spare, just in case I screw something up. So, when I purchase another head, I'd like to know that the part I'm buying will do what I want it to do. From what I see of your car, I'm sure you didn't just throw it together. It looks like a lot of time & thought went into it. Before I spend money 0n parts for my car, I'd like to know that it will be money well spent , for parts that will do what I want them to do. And yes, I'd also like some of the cool factor when people look under the hood & see dual or triple carbs & dual exhaust. And, lastly, even the Guru, when asked about the head, if purchased from him, didn't say that the head would definitely be a milled head from a 237 engine I should ask him how He tells the difference. His price for a head, already milled, is very reasonable. As usual the shipping adds to the cost significantly, compared to the cost for the head.

Edited September 8, 2014 by janan5243

[SQ4MN]

This is my opinion. Your car will last longer if you don't mill the head. If you do you will most likely not FEEL any difference. The small increase in compression obtained from milling the head will result in less than 5 horsepower. The best thing you can do to get good performance is to have a fresh engine or one with equal compression.These old flathead six engines are not performance engines. They were designed to be smooth trouble free long life engines and they do that quite well. I have 2 carbs and a split exhaust manifold and an engine that is in fine mechanical condition, it has a Crane ignition. All these things look great and the little 48 coupe sounds great. It runs like a top and uses no oil. As far as performance goes if it was measured against a stock plymouth it may be slightly more powerful. Measured against ANY modern car with even a 4 cylinder it is going to be the loser. I owned these cars as a kid and I love it now because it is everything I dreamed of as a kid but could never accomplish. It is a great cruiser and is comfortable, it is different from the crowd. I also own some fast cars but thats another story, if you're looking for performance a flathead six would probably be the very worst place to start. I also have a Ford rear end in my Plymouth with 3.50 gears, the car cruises on the hiway just great.

[dpollo]

Refer back to Plymouthy's comments.   Spitfire heads came on 251 engines  bore 3 7/16 by stroke 4 1/2.

 

     Your Desoto is likely a 236    3 7/16 bore, 4 1/4 stroke  so a Spitfire head would reduce compression if placed on your engine,

 

   so would the head from any engine with a larger displacement.   If you want to raise compression, substitute the head from a Canadian 218

 

 bore 3 3/8, stroke 4 1/16.    Mill enough to get the gasket surface flat and your compression will be boosted somewhat.... at a guess maybe to just under 8 to 1

 

 but you can do the arithmetic based on stock compression ratios of the early 50s.  ( 7 to 1 )  now put your thinking cap on and go back to Plymouthy's comments. 

[janan5243]

I was surprised to see a new post on this old thread. Unfortunately because of business restraints I haven't had time to do much to car. Thankfully, it runs good, so what little use it got last year was trouble free. I may have finally hired someone to work my hardware store that I can trust & is dependable. That will free me up to put some time in on car. From all advice & info given, ( yours included), I think the easiest & least expensive solution would be to have original head milled & install with new bolts.That way I'm not guessing about what size engine head came from. I know it is original head that has never been off car. Will then play with dual carbs & exhaust as time allows. I had spoken to George Asche & he felt engine could handle that. Thanks to all for input & info.

Edited February 5, 2016 by janan5243