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Thread: How much compression can I get away with? Champion 185 with an Eddie Edmunds Aluminum Head

  1. #1
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    How much compression can I get away with? Champion 185 with an Eddie Edmunds Aluminum Head

    Bringing a 1947 M5 back to life... I initially considered replacing the champion 6 with a modern V8. My dad strongly protested so we compromised on a rebuild with an attempt at increasing the power it would make. Over the last year I was able to locate an Offenhauser dual inatake and carbs, a split exhaust manifold, and of all things, an Eddie Edmunds aluminum cyclindar head made back in the 50's. The machinist has it all mocked up now and has measured everything. He determined we are now looking at a 9.6 to 1 compression ratio, largely due to the smaller chambers in the aluminum head. 9.6 to 1 would be no big deal in a modern V8 using aluminum heads. I just want to check with the SDC community to see if this all sounds good as it relates to a 185 CI champion 6 cyl? It should run just fine on premium pump gas, and I would expect the aluminum head to disipate the heat just fine. Are we overlooking anything, or creating other potential problems? Sure appreciate any feedback. It's getting pretty hard to find anyone who has much experience hot rodding Studebaker sixes anymore.
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  2. #2
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    Quote Originally Posted by jjesien View Post
    Bringing a 1947 M5 back to life... I initially considered replacing the champion 6 with a modern V8. My dad strongly protested so we compromised on a rebuild with an attempt at increasing the power it would make. Over the last year I was able to locate an Offenhauser dual inatake and carbs, a split exhaust manifold, and of all things, an Eddie Edmunds aluminum cyclindar head made back in the 50's. The machinist has it all mocked up now and has measured everything. He determined we are now looking at a 9.6 to 1 compression ratio, largely due to the smaller chambers in the aluminum head. 9.6 to 1 would be no big deal in a modern V8 using aluminum heads. I just want to check with the SDC community to see if this all sounds good as it relates to a 185 CI champion 6 cyl? It should run just fine on premium pump gas, and I would expect the aluminum head to disipate the heat just fine. Are we overlooking anything, or creating other potential problems? Sure appreciate any feedback. It's getting pretty hard to find anyone who has much experience hot rodding Studebaker sixes anymore.
    9.6:1 is no problem on a modern engine which has knock and oxygen sensors and precise, computerized instantaneous adjustment of timing and fuel mixture. On an engine with fixed timing advance and fixed carb jets, 9.6 is going to be close to pre-ignition at high temps and large throttle openings. Aluminum heads make very little difference. Clean up any protrusion/sharp edges in the combustion chambers and you "might" get away with it if you run cold plugs, mild cam and watch your timing advance. If you do all that and manage to avoid pre-ignition, It'll make about the same HP as if you'd built it with 8:1 compression, so what's to gain?

    Even on premium gas, and with a tad of carbon build up, I'll bet you'll be looking for a thick head gasket before you hole a piston or knock the rod bearings out of it.
    Last edited by jnormanh; 10-03-2013 at 06:22 PM.

  3. #3
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    Probably your guy measured everything correctly, but with a flathead, there is so much surface area, it's really difficult to get an accurate calculation. Talk to some flathead Ford guys, but anything more than 8:1 on a street flathead is very unusual and very challenging to tune.



    The one area a flathead needs help is fine tuning on the ignition and carbs. You'll want an adjustable vacuum advance and get to know someone with a Sun machine and I'd invest in an O2 sensor and gauge. It's possible to find the sweet spot between compression, air/fuel ratio and ignition advance. If the work isn't done, overheating pinging and total destruction are probabilities.

    jack vines
    PackardV8

  4. #4
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    In an L-head engine the area around the valves should also be included in the combustion chamber volume. It won't amount to much though, probably lower the ratio about .1 or .2. What about relieving the block? That would lower the compression ratio significantly and improve flow .
    <img src=http://forum.studebakerdriversclub.com/image.php?u=376&type=sigpic&dateline=1407459320 border=0 alt= />

  5. #5
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    With a total of zero experience on any flat head engine, may I offer the suggestion of trying out the combo, and if the engine cannot behave...then try water injection? It sounds like a really cool retro combination, and that head is really eye candy. Truck looks to be in good shape. good luck with the engine. junior.


    54 Champ C5 Hamilton car.

  6. #6
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    I'm no expert on this subject but do wonder if the high compression ratio might put out more torque than the bottom end of this little engine could handle. But I do know that this could make one helluva propane conversion. The pre-vaporized fuel would abate the compression ratio issue and pre-ignition would not be a problem. The carbs could be set up as a single or dual with LP/Gas mixers. Power flow would darned near equal fuel injection. Just an idle mind following the thread.

  7. #7
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    Thanks to everyone for the info, though I have to admit I'm a bit disapointed. I guess I expected a little more encouragement about staying with a Stude engine and get what I could out of it. I know Bill Cathcart was doing some impressive things with these flatheads about 10 years ago to improve performance even to the point where he and a partner were casting their own aluminum heads. Sure wish I had access to his knowledge. Here is a comment from a Hemmings Motor news article (Jan 2005) where he was interviewed.

    "Each engine he builds completely to the customer's tastes, from 90hp stone stockers up to outrageous (for a Studebaker flathead six) 140hp naturally aspirated, non-stroked, multi-carbureted fire-breathers. Prices range from $2,800 for a basic rebuild to as much as $4,300 for the heavy hitters".
    "Bill said he finds the engines fairly simple to work on and rather similar to the flathead Ford V-8s, straight-sixes and inline-fours. Studebaker built the Champion engines, which generally displaced about 170 cubic inches, and the Commander engines, which generally displaced about 226 cubic inches, in various forms back to the 1930s and through to 1961, when the company dropped the flathead in favor of a new overhead-valve design."

  8. #8
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    There's an article in the September 1955 edition of Rod & Custom about hopping up the Studebaker 6. The article begins with a stock 170. They keep the bore and stroke stock in this build. Milling the stock head .070" produced a compression ratio of 7.8 to 1 on an unrelieved block. They list the aftermarket Morgan, Weiand and Edmunds heads as having compression ratios up to and above 8.5 to 1.

    The build included dual carbs, a cam, a set of matched and lightened valves with springs and a set of special pistons.

    On the intake valves, the seats and valve pockets were reamed out with either a 70 degree piloted reamer or a 70 degree strone on a die grinder to an i.d of 1.260" to take a valve of 1-15/32" (1/8th inch larger than stock.) Intake seats were cut to 30 degrees to raise the effective valve lift. Exhaust was left alone except for a light once over with a polishing stone.

    The cam was the Morgan H-1000 with a duration of 256 degrees and .378" lift. The valve springs applied about 10 lbs additional pressure. Valve guides were kept at stock height although they mention they could be beveled slightly. They mention that since the valves in the Champ engine are titled slightly off the vertical (like in the Ford flat head) a relieve job is a help. Maximum relief was noted as 5/32" with the warning that any more would create the possibility of a scorched upper compression ring.

    The bottom end of these engines is noted as being particularly strong.

    I have no experience with any of these modifications, but thought they might be useful.

    Perhaps a slightly thicker head gasket could bring the compression down a little?

    I talked to Bill briefly a couple of years ago, and he told me by putting the aluminum head and the dual carbs and split exhaust would do a lot to wake up the engine--so you might be further along than you thought.
    Dave Nevin
    Corvallis, OR
    1953 Champion Deluxe Coupe
    Stud-e-venture blog

  9. #9
    President Member LeoH's Avatar
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    Complete engine ignorance here: if you were to put on a dual carb intake manifold, would you put on 1 or 2 barrel carbs and why or why not?

  10. #10
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    Two single barrel carbs have sufficient flow to feed a 185" flathead 6-cyl. Thus, 2x2-bbls would not accomplish anything.

    If I were ever reincarnated as someone who wanted to build a Champion, I'd consider an easily constructed manifold using three tubing stubs to mount three single-barrel motorcycle carburetors. They're physically small, cheap, sized right and would be aimed straight down the ports.

    jack vines
    PackardV8

  11. #11
    President Member LeoH's Avatar
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    Thank you, my first thoughts were two singles would be enough and if you went to two two barrels you might have to worry about running too rich but I don't have enough experience to figure that out on my own.

  12. #12
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    Good on you for running the old 6 pack, im doing the same to my champ for my 51 sedan but way over here in New Zealand.I need a Dual carb manifold and carbs if any one nows of any for sale.

  13. #13
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    Quote Originally Posted by jjesien View Post
    Bringing a 1947 M5 back to life... I initially considered replacing the champion 6 with a modern V8. My dad strongly protested so we compromised on a rebuild with an attempt at increasing the power it would make. Over the last year I was able to locate an Offenhauser dual inatake and carbs, a split exhaust manifold, and of all things, an Eddie Edmunds aluminum cyclindar head made back in the 50's. The machinist has it all mocked up now and has measured everything. He determined we are now looking at a 9.6 to 1 compression ratio, largely due to the smaller chambers in the aluminum head. 9.6 to 1 would be no big deal in a modern V8 using aluminum heads. I just want to check with the SDC community to see if this all sounds good as it relates to a 185 CI champion 6 cyl? It should run just fine on premium pump gas, and I would expect the aluminum head to disipate the heat just fine. Are we overlooking anything, or creating other potential problems? Sure appreciate any feedback. It's getting pretty hard to find anyone who has much experience hot rodding Studebaker sixes anymore.
    I really like your truck. I too am looking to "wake up" my flathead a bit with some vintage speed parts so I wish you the best in your endeavor...


    1950 Commander Starlight Coupe
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  14. #14
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    jjesien,

    you have a pmail.

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