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Going Supersonic, Texas version..

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F Bill View Drop Down
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    Posted: 02 Feb. 2013 at 10:54pm
Well, while Sam was tormenting us today with his What am I postings, I finally went out to the shop and worked on some old heads I had around. Long story short, I finally got to measure the actual combustion chamber volume of the Supersonic and the stock non ribbed head.
 
Here's the Kaiser Supersonic head for those who haven't seen one. Legendary in its performance possibilities for the flahead, stories tell of awesome power improvement and mileage increases from installing one, but.... ya know what they say about stories when they involve old jeeps.
Here is what the combustion chamber looks like.
   If you are used to jeep cylinder heads, this head looks a little shallow compared to the stock one.
 
Here is the stock head I used. Both heads were wirewheeled and painted grey, partly so you guys could see the details better, but also because that was the only paint I had that worked, and I wanted to keep the rust away.
Bottom side: Notice the little shelf in the chambers, away from the valve end. It almost looks like the SS head was made by shaving off enough material to eliminate this shelf. Measurements confirmed this.
Top side showing part number and casting date, and .014 valve clearance spec.
 
I decided I would try and CC the heads, so I looked on the net to see how others did it. I found a guy that did it with a large graduated syringe, so Off to the drugstore I went. Oops, they were already closed for the afternoon.. (Small towns, ya know)..SO I did what every red blooded American does on Saturdays... I went to a yard sale, and found a 20cc syringe there. A quick stop at the local hardware store for a cutoff scrap of plexiglass, and I was set.
 
I just drilled a small (1/8 or so) hole in the plex, coated the head gasket surface with vaseline, and mixed up some blue water with food coloring, so I could see it better. After pressing the Plex in place, all I had to do was use the syringe to put a measured amount of water in each combustion chamber I was measuring. It took 4 fills to do the SS head, 80CC worth.  The stock head I did a few times as I was learning how to get a good start and end point on the syringe, and I ended up with 89cc for it.
 
Note... I have no way to know if someone already had machined down the SS head or the stock one. If anyone else has a SS head off their engine, this is a pretty simple test to do and it would be nice to have a second data point that matches..
 
Now to do the math and figure out the CR of the smaller Combustion chamber. Any of you math whizzes want to take a crack at it, be my guest.
 
Supersonic, head number 7xxxxx   80 cc.
Willys , head number 640161         89cc.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb. 2013 at 11:01pm
I forgot to show you the gee whiz high tech cc setup..
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb. 2013 at 11:32pm
You're always a step ahead of me. I was just about to publish that the supersonic was just a planed 2a head.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 02 Feb. 2013 at 11:41pm
Originally posted by Joe Friday Joe Friday wrote:

You're always a step ahead of me. I was just about to publish that the supersonic was just a planed 2a head.
 
Yeah, but it has the neato keen Supersonic lettering!!LOL,
 
I must have had a brain fart, I can't figure out how to do the CR calculations for this.. 6.48 is what stock is, 7.1 is supposed to be the SS ratio but figuring it out longhand I am missing something. EDIT: Brain fart over, finally...I was doing the math wrong, of course..The measurements I got work out to 7.09 :1 for the Supersonic head I have, if the stock head is really 6.48:1.  Without measuring the volume of the head gasket space and allowing for any negative deck height of the piston,or the little round divot in some of my pistons here, it will only be an approximation.
 
I did see some posts where Porskar did measure his SS head and got a slightly different volume, but not differing by a whole lot. (I think he got 75 ML which is the same as 75cc. )There were several posts where guys had quoted the CR on the SS as 7.0 to 7.1 to one, including one on the G 503 that Larry had quoted.....so I am probably close with my measurements.
 
I removed about 9cc from the stock combustion chamber and guess where the blue waterline was? Righto-just below that shelf... which is why I said measurements confirmed the SS head was made by milling off enough of the stock chambers to get the ratio desired. I can't see any significant change in the shape of the chambers between the two heads.
 
Guess it is off to the machine shop to mill a few thousandths off my stock head on my next rebuild. I think the Supersonic might end up on the DJ with doors eventually. It needs more power. Big smile


Edited by F Bill - 03 Feb. 2013 at 3:25am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote jpet Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 12:20am
.... so is the SS head shorter by the same amount in over all height?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 12:25am
Yup, approximately... I did a rough backwoods measurement with my try square and there is about an 1/8 difference (actually a little less) in both the height of the head overall to the bolting surface, and the depth of the combustion chambers. When I find my digital calipers I will get ya an exact measurement. (I can only find one missing tool a day, evidently, and I had already found the Shop vac.)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote garage gnome Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 12:38am
Cool! Thanks Bill, now I feel better about the swap I did. Thumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Joe Friday Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 2:43am
I found the old posts from Jim Allen regarding this.The only difference is that the thickness of the 6.48:1 head is 2-9/64 thick and the 7.0:1 head has been planed down to 2-7/64. So other than the cool supersonic name cast on the head, save your money.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote garage gnome Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 3:07am
Eh, I'd still rather have the supersonic head. It gives my jeep a more or a 50's hot rod look (and feel?) to it. LOL Wink

I like cool factors. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 3:27am
Edited the above to reflect the fact that my brain actually CAN do math, despite what my 12th grade math teacher thought when I graduated...
 
Supersonic calculated   CR.....7.09:1
Stock head CR from specs.....6.48 :1
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepFever Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 4:50am

So it appears that "Supersonic" performance might only be a machine-shop away?  LOL

 
More evidence:
 
I do not have a "standard" head,  but do have a "Supersonic",  and an "Industrial".  My measurements show the Supersonic is thinner, (measured from headbolt-surface to block,  and sparkplug-seat to block).
 
The Industrial (bottom in this photo) has some "open air" above the piston.  Which would account for its even lower compression ratio than standard.  (FBill's standard head did not have this extra open volume)
 edit:  I noticed later, that the transition is different also,  (outlined in blue)
 
A machine shop might be able to shave the head and give Supersonic performance,  but can not put "Supersonic status" . .  visible to anyone lifting the hood. (Nate's "cool factor")  LOL
 
 
 
 
 
 
 


Edited by JeepFever - 03 Feb. 2013 at 9:25pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 5:11am
Oooh I see a sleeper industrial head conversion in your future....How thick overall is the industrial head?
 
It is interesting that the shelf seen in my stock head is not visible in the industrial one.
 
Here's some head thickness specs from Willys Motors post a while ago. I will try and find the specs for the 640161 and Supersonic heads later.


 
Post Options Post Options Quote Willys Motors Quote Post ReplyReplyDirect Link To This Post Posted: 02 Dec. 2010 at 9:16pm
800376 head thickness = 2-9/64 = 6.48 compression ratio
640035 head thickness = 2-7/64 = 7.0:1 compression ratio
 
The 800376 is a M38 head and the 640035 is a high altitude optional head.


Edited by F Bill - 03 Feb. 2013 at 5:21am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 5:31am
Here's part of an interesting post from the g503 forum back a few years ago..

Compression Ratio Calculations

Postby ArmySailor » Wed Aug 13, 2008 10:03 am

I did this research for my "Classic Mode" column in the now defunct J-Rations Magazine. Rather than have it languish and never be seen, I though I'd post it into a place where it might do some good.

The high compression head for the flathead Willys (part # 640035) was a standard head with an extra 0.035-inch milled off. It was stamped “7.0” on the front of the thermostat housing and delivered a 7:1 compression ratio, the same as the Kaiser Supersonic engine, a rebadged Willys engine used in the Kaiser Henry-J. The Henry-J made 68 hp at sea level, five more ponies than the Willys. At 6K feet, 7:1 should gives back most of what you lose at that altitude. In milling the head, you increase the compression ratio by reducing combustion chamber volume. To get a 7:1 ratio, you want the volume of the dome in the head to be about 82 cc, as measured via “CC-ing” the head with the spark plug installed. The standard 6.48:1 head dome volume was about 90.5 cc. It’s important to know if your head has already been milled (for reasons I outline later) before you have it milled. You can tell by measuring the thickness of the head from the mating surface to one of the machined head stud bosses on the corner of the head. A standard head will be around 2.1406 inches (plus or minus a few thousanths). If you want to go for the 7:1, then you want the total thickness of the head to be around 2.109 in., which should not be exceeded unless you know what you are doing. The thickness of the head deck and combustion chamber roof is about a quarter-inch, so you have a little room to play, but don’t be careless. Verify the chamber volume by CC’ing. There are some dangers in removing too much material, strictly from the performance level. When you skim material from the head, it moves the roof of the combustion chamber closer to the valves. Taken to excess, that can create a situation called valve shrouding, which reduces airflow in and out of the combustion chamber.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote porsskar Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 9:45am
FBill, thank you this was a very interesting thread. You have really made research on this!
Amazing Willys did not use the supersonic ratio from the very beginning  with the military versions (what is wrong with a few horses more?)

 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bear Gulch Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 1:46pm
  F Bill & All : Thanks for the info & a very interesting thread. Pushed a 45 into my shop just before I left for winter. I was short on time, but noticed Supersonic head & small distributer cap of approx 2.5" diameter ? can anyone shed any light on any visable characteristics to identify complete Supersonic engine vs jeep ? Are there any "lower" diff's ? Thanks !!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 4:11pm
Here's some more head part number info that Oldtime posted on the Cj3B dispatcher board a while back.
#639660 XXX ratio... production ends sometime in the late 40's
#640035 7.0 / 1 ratio... was both a CJ-3A and DJ-3A option
#640161 6.48 / 1 ratio... was standard on all CJ-3A and pre 1963 DJ-3A
#649172 XXX ratio... was used with very early SW and PU
#807763 6.48 / 1 ratio... I believe this head begin production around 1953

I'm not sure about that last number as it looks awfully similar to the one BA mentioned later in the post:
the 800376 is a civvy and MIL (m38) application. found many DJs,
It's also the 6.48-1
BA
 
It is interesting to note that neither 807763 or 800376 is listed in the 55 Parts price list.  640161  6.48 heads were going for around $18 at the time....Shocked while the lower CR 642509 head was $24....list price.

On page 41 of the 1955 master parts list only two heads are listed:

#640161  6.48 CR
#642509   6.40 CR (this is a new one to me, perhaps it is the industrial?)
no mention of a higher compression head.
 
In the oct 1949 Ord 9 SNL G-503 publication the heads are listed as:
 
WO-A1534    Chain Drive Cam cylinder head
FM - GPW6050 Ford cylinder head for the GPW
WO-641049-D Gear drive cam cylinder head. 
 
No Compression ratios given. I have a GPW head I can measure if it interests anyone.
 
Sure are a lot of different heads over the years..
 
Does anyone have any later parts books than 1955  that might have the high compression heads in them?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote F Bill Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 4:14pm
Porsskar there is a tag on the side of a Supersonic block identifying it as a Supersonic. Also in another thread it is mentioned they used the later carb and manifold that was used on the DJ, with the studs at a 90 degree orientation to the standard Cj2A setup. Throttle linkage will be different.
 
Does your distributor have a vacuum can on the side? Or is it totally mechanical advance? THe Kaiser SS had a vacuum can according to another poster...
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Post Options Post Options   Thanks (0) Thanks(0)   Quote JeepFever Quote  Post ReplyReply Direct Link To This Post Posted: 03 Feb. 2013 at 9:09pm

Originally posted by F Bill F Bill wrote:

Here's part of an interesting post from the g503 forum back a few years ago..

You can tell by measuring the thickness of the head from the mating surface to one of the machined head stud bosses on the corner of the head. A standard head will be around 2.1406 inches (plus or minus a few thousanths). If you want to go for the 7:1, then you want the total thickness of the head to be around 2.109 in., which should not be exceeded unless you know what you are doing.

My Industrial head measures 2.140,  so it appears that these lower compression heads are not simply thick standard heads.   Also as I look closer,  the combustion chamber shape is different.  You can see in my photos,  not only does it have "air" over the pistons,  the transition is different.  I modified the photo to outline it.
 
 
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My SS head measures 2.090 (not 2.109),  I wonder if it was machined at some point in its life,  and I have a Super-Super? LOL
 
 
 
Originally posted by F Bill F Bill wrote:


 Here's some more head part number info that Oldtime posted on the Cj3B dispatcher board a while back.
#639660 XXX ratio... production ends sometime in the late 40's
#640035 7.0 / 1 ratio... was both a CJ-3A and DJ-3A option
#640161 6.48 / 1 ratio... was standard on all CJ-3A and pre 1963 DJ-3A
#649172 XXX ratio... was used with very early SW and PU
#807763 6.48 / 1 ratio... I believe this head begin production around 1953
I'm not sure about that last number as it looks awfully similar to the one BA mentioned later in the post:
the 800376 is a civvy and MIL (m38) application. found many DJs,
It's also the 6.48-1
BA
Odd . .  Mine is casting #807763 and is Industrial.   I thought all the Industrials were lower compression,  but this DOES have 6.48 cast right into it.
 
So now I wonder,  does this odd-ball chamber shape have any advantages?   Maybe shaving it would to SS volume WOULD give me that "sleeper" you mention.  LOL
 
I need to find a syringe and do some measuring.


Edited by JeepFever - 03 Feb. 2013 at 9:22pm
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