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Head comparison


Bryan
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Got a head with the engine block I got.  Looks different from the one on my 1948 Dodge. 48 Dodge had the block replaced years ago with a 1949 Plymouth block, but reckon they used the 48 Dodge head, don't know.  See picture.   Might have to CC both to see which has smaller chamber.  Duhhhh - the shadow made me think the right head had symmetrical chambers..just soot imprint.  Both heads have same shape.

Head  comparison.jpg

Edited by Bryan
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A few weeks ago I got a chance to talk to Mr. Asche. When the conversation got around to milling heads, he said that generally stock, uncut heads measure around .500" from the gasket surface to the valve pocket of the combustion chamber and that total thickness was around 2.00".

Obviously CCing them will tell you more, but is there a known Stock number to compare to? 

 

I looked back at some pictures from my car and was able to make out the head part numbers.

1120803-5 installed in 1948 Plymouth, on p15 engine

 

1405849-10 installed on p24 engine, has late 1952 date.

I have been meaning to pull the '53 head, I will try to take matching comparison photos and measurements, Plymouth 217 vs Dodge 230.

Edited by FarmerJon
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The several 23 inch supposedly stock heads I have measured were 2 inches when measured from the flat of an outer headbolt mounts to the bottom of thehead surface.  Milled heads should be less based on the material removed.  Don't know if that helps or makes sense. 

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9 hours ago, FarmerJon said:

.. total thickness was around 2.00".

Obviously CCing them will tell you more, but is there a known Stock number to compare to? 

 

I'm just comparing between the two to see which has the smaller CC, but that helps also to know the stock thickness of the heads, so I'll be comparing apples to apples.

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On 1/12/2022 at 9:10 PM, FarmerJon said:

... is there a known Stock number to compare to? 

 

I looked back at some pictures from my car and was able to make out the head part numbers.

1120803-5 installed in 1948 Plymouth, on p15 engine

 

....

 

I looked at a head that I'm pretty sure came off of my 1st series 49 P15, and the number is 1120803-8  (My brother also had an engine out of a 51, and he was thinking the head was his.  A lot of stuff was stolen, so one or the other disappeared over the years, just like they stole my extra bell-housing out of the trunk.  Sad thing is that they probably just stole it for scrap.)

The only other markings on it are a 12-1, and an NH, where the right leg of the 'N' is also the left leg of the 'H'. 

 

The engine that came with my 46 (disassembled) is a 55 model, and the head has the small hole for the temp sending unit (for the electric sensor).

The number on it is 1616823-4.  Also has a date code of 12 10 54, which fits with it having been installed in a 55.

Edited by Eneto-55
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Folks have said that putting 218 heads on a 230 will raise compression.  Here's my theory based on observation of the two different engines 46 218  vs 56 230.  The pistons on the 218 engines do not come completely up to the top of the cylinder at TDC owing to a shorter stroke.  The 230 piston at TDC comes up higher, nearly flush to the top of the cylinder.  If a 218 and 230 have the same or very nearly equal compression ratio, the 218 head must have a smaller combustion camber to achieve the same squeeze with a tdc piston  position lower than the TDC position of the 230.  So putting the 218 head on the 230 must yield a tighter combustion chamber space.

 

I did try to do a measurement using colored water, and measuring the amount needed to fill the head space but I don't thing I got it correct enough to derive a definitive answer.  I guess you can get accurate data using a bolted down piece of plexiglass and a large syringe to inject preside amounts of water or maybe this would be a place where atf or Marvel mystery oil would work.

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In order to get an accurate reading, you need something like a piece of plexiglass to keep the surface tension of the liquid from throwing off the reading. I used a grease to seal the Plexi to the head. 

Alternatively you could use a non water based modeling clay or 'silly putty' to press into the chamber. Once you have it to shape and leveled across the top, pull it out and drop it into a graduated cylinder that has a known amount of liquid already in it and note the change.

Ie if your measuring cup has 50cc in it. You drop your chamber mold in and the level rises to 150cc, you have a 100cc chamber.

 

My work may have some scratched up Plexi they are throwing out, I will see if I can nab any. 

 

Bryan, did either of your heads have a date code cast in?

 

Edited by FarmerJon
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Interesting theory, Greg. It got me thinking, so I took a look at my parts catalog. In the B-series trucks, the 1/2 and 3/4 ton (B & C) trucks got the 218 and the 1 ton (D) got the 230. I see that indeed the 218 and 230 engines have different head part numbers. (Serial number break is likely for internal vs. external bypass) But it seems they also had a low compression head available for export models. I wonder if the car side did the same thing. 

B016CC5A-6B23-40E8-A979-CEB53419D81F.jpeg.598d5faafafb620eef66d66d12fc12d5.jpeg

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The problem with part number comparisons is that they do not tell you what is different.  If one application requires a different sized hole for the temp sending unit then it will have a different part number though everything else can be the same.  You can sort of see that in the low compression head listings, all have the same compression ratios but there are quite a number of different part numbers.  Wonder what the difference is.

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I was thinking the same thing. Looking at the part numbers, they are all 7 digits, no -#.

Eneto has the same part # head as me, just a different -#.

I wonder if it is a mold # or drawing revision #. At my work the -# is revision. Sometimes it changes based on actual changes, sometimes due to changes in drawing notes or procedures. If it was mold # it could just be there for QC purposes.

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My 228 engine, that I had bored out to 237 should indeed have raised compression. Just based on the larger diameter bore. I suspect the 228 head should have a smaller cc combustion chamber too, when compared to a stock 237 head. I also have a spare block and head here, a 218. All mentioned here are 25" long engines. It would be interesting to put the 218 head on my 237 engine. 

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3 hours ago, FarmerJon said:

Eneto has the same part # head as me, just a different -#.

I wonder if it is a mold #

 

It is the number of the mold that casting was made from.  It is for QA purposes, so that if there is an issue they can narrow the iffy mold down quickly.  When casting heads the foundry will use a number of molds to facilitate mass production of the castings.  They have to be able to track what casting came from which mold, the -# does that for them.

 

It is not the number of revisions to the mold, as some say.  If the mold is revised the part gets a new casting number.  The final machining will set the part number. 

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