Heads - anybody measured?

[Bryan]

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.

Edited January 13, 2022 by Bryan

[FarmerJon]

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 January 13, 2022 by FarmerJon

[greg g]

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. 

[Bryan]

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.

[Eneto-55]

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 January 14, 2022 by Eneto-55

[greg g]

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.

[FarmerJon]

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 January 15, 2022 by FarmerJon

[Merle Coggins]

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. 

[Sniper]

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.

[FarmerJon]

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.

[keithb7]

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. 

[Sniper]

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. 

[Bryan]

On 1/12/2022 at 10:31 PM, greg g said:

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. 

I went out and froze today doing some measurements on the 2 heads of this post on the places you mentioned. The 53 Dodge head measured 1.9420 to 25.   The old 49 head measured 1.9155, tried other corners and got 1.9175 to 85.  I tested my digital caliper with a 123 block at the same time, got exactly 2.000 on the 123 block.   Tried to measure from the head surface to the area the valve would hit near the edge (about even with the spark plug).  Got between .4980 to .5150 on both heads. Carbon build up and rust on both, but were consistent.

[Eneto-55]

Does anyone know if MoPar had their own foundries?  Did the heads come from the same foundry regardless of where the car was assembled, and/or were the engines assembled in a single plant, and shipped out to the different automobile assembly plants?

Edited January 28, 2022 by Eneto-55

[FarmerJon]

Just came across this today, It has several pictures of Hudson flathead combustion chambers- stock is much like ours. Then Edmunds, Clifford and their new "twin vortex" design. 

https://www.jalopyjournal.com/forum/threads/potential-to-bring-back-a-hudson-6-performance-head.1242895/

 

Edited February 4, 2022 by FarmerJon

[Bryan]

20 minutes ago, FarmerJon said:

Just came across this today, It has several pictures of Hudson flathead combustion chambers- stock is much like ours. Then Edmunds, Clifford and their new "twin vortex" design. 

https://www.jalopyjournal.com/forum/threads/potential-to-bring-back-a-hudson-6-performance-head.1242895/

Neat.  But you would think any swirl would be needed on the compression stroke when the mixture is about to be ignited.   Wonder how one ear with a gradual slope from side to side above the piston ending in one ear would do?    Lastly.. ANYBODY HAVE A REMOVED HEAD and measured the exact thickness between the gasket surface and the corner flat surfaces where the bolts go?  The 53 Dodge head I have measured 1.9420 to 25.   The old 49 head measured 1.9155, tried other corners and got 1.9175 to 85. 

[Bryan]

Could use some exact measurements.   Please? ?

 

[47 dodge 1.5 ton]

I measured a 1959 265 head this morning. Head thickness measures 1.915” , valve pocket depth .490-.510”(has carbon).

[47 dodge 1.5 ton]

[James_Douglas]

The last head I did required that we place the head in a mill and equalize all the bolt bosses as they were not all the same. So, be careful measuring a head thickness.

 

I sandblast the heads then I CC them. I then place it on a block (with an old gasket) with a crank and cam and rotate it. I place modeling clay across the valves and see how much clearance is left after I run the thing around. That is the only way to know for sure that you will not have a valve hit the head as these heads have been cut too many times.

 

Once I am convinced that there IS room to use the head I then take it in and have it cut. I then CC it again and also do the valve clay thing again just to make sure. With the head CC, the gasket numbers, I can then come up with the exact compression ratio I want. In the event I need more room, like if the block was decked too many times, I would order a solid copper head gasket in the needed thickness.

 

If you look at older posts between myself and Don you will see we came up with a general rule as to how much you can taker off and what that does to the compression ratio all other things being equal. Of course our work was on the 25 inch blocks, so I would take it with a grain of salt on the 23 inch engines.

 

CCing is the only route to knowing what you are getting no matter the engine or head.

 

James

[47 dodge 1.5 ton]

  The head I posted is a virgin head. I agree that it needs to be cc’d.  Another method for true accuracy would be a 3d scan. When I get that far in my motor, I plan to check a few of the heads I have here and hopefully a spitfire head(not acquired yet). 
  We have used scanners now for pattern work (past 6-7 years or so) at my day job and this definitely would be justified valuable. Just wanted to mention this as some may know of folks that work in foundries or have access to a scanner.

Edited February 5, 2022 by 47 dodge 1.5 ton

[Bryan]

19 hours ago, 47 dodge 1.5 ton said:

  The head I posted is a virgin head. 

Thanks a bunch. Your measurement is exactly what I was wanting to know.  Can figure that my heads have not been milled either.  

[James_Douglas]

When looking for something else I ran across my noted from 2010...note this is for a Desoto 25 inch block and an NOS head I used:

 

Max out of flat for the block or head on a flathead six is:  Length < 0.006 and width 0.002
Finish on block and head should be an RN between 30-60.
Felpro gaskets (7256) for these heads contribute to about 18.5 CC on each cylinder.
 
You get a loss of about Seven (7) CC's for every 0.024 taken off the head.  Using some milling charts that are floating around I get about one (1) CC loss for every 0.0034 taken off the head.  A stock head is about 110 CC's and is 1.930 thick.
 
So if you want to end up with a 7.7 compression ratio, you need about 84 CC's assuming a gasket thickness of 19 CC's and a deck of ZERO on the block.  I milled mine another 19CC's to get it down to about 84 CC's.

 

I went through the trouble of polishing all the undersides of the combustion chambers and equalizing then to within 1 CC. Helps with the idle to try and get the final compression ratio as even as possible. But that is nit picking...

 

Given that some of the chamber designs are a little different, this needs to be taken with a gran of salt. Take off a little and CC the head, then take some more and CC the head. Because of the basic shape 0.0034 first cut will take off less than later 0.0034 cuts. So don't try to cut too much off in one pass. Yest the machine shop will not like it and they will charge you a set up fee each time, but do it in steps so you do not screw up the head.

 

Also, make darn sure they mill the the top of the head boss's where the bolts/nuts go to make them the same before they mill the head. Those boss's are not always on the same plane and the head can be milled into a wedge shape if they are not. I have seen this. I am not sure why some of them are off, but they can be.

 

James

 

[48jumpdoors]

On 1/14/2022 at 8:43 PM, greg g said:

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.

so I just pulled the head off of my 1948 Plymouth because I had zero compression on number six. I found that I had a stuck valve which I have since freed up and is now functioning correctly. While freeing up the valve I noticed that the pistons came all the way flush at the top of the cylinders, so your comment of a 230 coming all the way up flush caught my eye. So can I assume that I have a 230 in my Plymouth? The motor has 0.040 oversized pistons in it so possibly when it was rebuilt a 230 crank was installed or maybe they found a Dodge motor to swap out? I took the head to have it inspected and to have 0.030 shaved off of it, do you think this is a good idea? after reading the above comments maybe I should just have the gasket surface cleaned up at a maximum?

[Sniper]

Minimum recommended piston to head clearance is .040", that can vary a bit tighter is you are adventurous.  Being that the head gasket is usually at least that thick, if not twice as much, you should be ok there, but verify.