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Mopar Flathead 6 Horsepower vs. Production Year

Discussion in 'The Hokey Ass Message Board' started by bbuswell, Oct 3, 2007.

  1. bbuswell
    Joined: Jul 18, 2007
    Posts: 22

    bbuswell
    Member

    I’m a newbie in the process of doing some upgrades on my 39 Plymouth P7 coupe and I have a question about flathead 6 horsepower that one of you guru’s may know. I recently purchased a 230 ci flathead 6 out of a 1950 Dodge (from a fellow hamber) to replace the 201 ci that is in it now. When I look at specs on the carnut.com website, they show a 1950 Dodge having 103 hp from the factory and a 1959 Dodge Coronet 6 having 135 hp from the factory. My question is, what is the reason for the difference in horsepower ratings between a 1950 flathead 6 and a 1959 mopar flathead? According to the specs on carnut.com, the only difference I see is that in 1959 the compression was 8 to 1 and in 1950 the compression was 7 to 1. Is that where the additional hp is found or are there other factors like 12 volt electrical, different cam, different carb, different head, etc? I’m obviously not looking for great horsepower from this setup but if I can pickup an additional 35 hp on my 1950 engine I would like to.
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    Thanks in advance
    Brett
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 26,406

    squirrel
    Member

    looks like compresion is the big change, it gradually increased from 53-58, and hp gradually increased also. valve timing appears to have changed slightly in 54, but not after.

    I don't know enough about them to tell you what else might have changed over the years. Head design might have played an important part.
     
  3. plym_46
    Joined: Sep 8, 2005
    Posts: 3,203

    plym_46
    Member
    from central NY

    Compression was the biggest factor. Internally the 230 engines are the same and parts are interchangeable. In 56 there was a 2bbl option that picked up 8 hp. Here is something you can try. Supposedly the head on your 201 engine has a smaller squeeze zone as the bore is smaller. So putting your old head is good put it on your newer engine. I have a 56 230 in my car. I found a fenton intake and am running dual carbs. I had the head shaved .040 and the blocked decked .010. pistons are .030 over. The machine shop guy calculated the Compression ratio at about 8.7 to 1. It is much more stout that the 218. Easily pull grades on the interstate, and is probably as fast from 40 to 70 as our daily drivers.

    There are a couple of fellows who do split intakes and split exhaust. One of them says you can go to .080 off the head block and still run regular gas (don;t even need lead substitute cause the old MOPAR engineers included hardened valce seats).

    Check out this wesite for split manifolds and front disc brake kits.
    If you don't want to split the intake, you can get on of those aluminum adapters and put a 2bbl on it either a Carter BBS or a carter weber. Check tom langdons site for other inlline 6 stuff.

    http://langdonsstovebolt.com
    http://rustyhope.com.

    Also you might want to drop in on the P15 D25 forum. A good community of MOPAR Flathead 6 enthusiasts.

    http://www430.pair.com/p15d24/mopar_forum/forumdisplay.php?f=1

    And the rest of the wesite for some good info on 40's Dodges and Plymouths

    http://www40.addr.com/~merc583/mopar/framesets/welcomeframeset.html


    One caution, Chrysler made 2 styles of flat 6 engines. Short blocks 23 1/2 in long head for Plymouths and Dodges, and the long blocks 25 inch long heads for Desoto and Chrysler. Then they complicated the mix by using 25 inchers for all displacement engines in Canada. So when ordering parts and accessories for your car measure the head and specify that measurment, specially if you find vintage manifolds at swaps or on auction sites.
     
  4. rockabillybassman
    Joined: Jul 17, 2005
    Posts: 2,770

    rockabillybassman
    Member

    All good advice from Plym46. There are some very knowledgeable folks at the p15-d24 forum mentioned above, it's worth your while. An example of how the compression crept up.... my 55 Plymouth 230 has 7.4 stock and is rated at 117hp. The good thing about that is it BEATS A 239 INCH FLATHEAD FORD V8 @ 100HP!!!!! :D :D :D
    Some handy parts sites for ya....
    www.oldmoparts.com
    www.rockauto.com
    www.vintagepowerwagons.com
    www.kanter.com
     
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  5. blackp-15coupe
    Joined: Mar 8, 2006
    Posts: 806

    blackp-15coupe
    Member

    <TABLE id=HB_Mail_Container height="100&#37;" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" width="100%" UNSELECTABLE="on"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">
    What a coincidence - I have a '39 Ply business coupe with a dead motor ( '46 Ply 218 cube). After some discussions and checking around, I'm going for a Dodge engine. The info I got is that the Dodge has a stronger bottom end and I want to start with a 230. I located a motor and expect to pick up tomorrow, a '55 dodge 230. It will undergo a rebuild (bore at least +.30), 3/4 cam, and I already have a Fenton head (which should boost compression to approx 9-1), Edmunds 2x1 intake, and Langdon headers. Exhaust system - duals with Smithys.
    This is pretty much what I have in my '46 coupe; Dodge 230 (out of a truck), Sharp aluminum head, Edmunds 2x2 intake (2 Holley Weber 2 bbl with re-popped Helling and Stellings cleaner), tube headers, tweaked dizzy with mechanical advance, and duals with glass-packs.
    Make sure to check out Tom Langdon's site and give him a call. he's a wealth of info. Also check Bluesky's site ; www.50Plymouth.com Pete is also a good source of info.
    Good luck with your project,

    Dave

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  6. Bugman
    Joined: Nov 17, 2001
    Posts: 3,485

    Bugman
    Member

    The '59 passenger car head is the best flowing of the 230 heads. The chamber is shifted in the head casting towards the valves, unshrouding them somewhat, making it easier for the air to get in and out. The head I'm designing for the 230 is based around the '59 car head.

    The problem with shaving the head for compression is that you loose flow because the valves are more shrouded. I've seen a very few people that had offset their heads using turned down head bolts. Obviously this isn't for everyone, but if you're chasing every last HP in your Mopar powered pulling tractor...

    Dave, you have Fenton and Sharp heads? Could you post some pics of both sides? I've never even seen a Sharp head before.
     
  7. Hudsonator
    Joined: Jun 19, 2005
    Posts: 335

    Hudsonator
    Member
    from Tennessee

    Do you have such a tractor? What kind?

    I'd like to hear some more about your head design and see some of those Fenton and Sharp heads too.

    Hud
     
  8. rockabillybassman
    Joined: Jul 17, 2005
    Posts: 2,770

    rockabillybassman
    Member

    Blackp-15coupe...... there's no difference in the bottom end between Dodge and Plymouth.... a 230 is a 230, end of story. I like your mods, but are you sure about the 9:1 of the Fentons? If they are stock I doubt they would be more than 8:1, although you'll pick up some from the overbore.
     
  9. 53dodgekustom
    Joined: Jun 18, 2006
    Posts: 878

    53dodgekustom
    Member


    Plymouth 218's don't have a cross drilled crank for oil.
     
  10. Bugman
    Joined: Nov 17, 2001
    Posts: 3,485

    Bugman
    Member

    Nor does the '59 Dodge 230 crank in my '55... To my knowledge, none of them are factory cross drilled.
     
  11. hkestes
    Joined: May 19, 2007
    Posts: 480

    hkestes
    Member
    from Plano, TX

  12. 53dodgekustom
    Joined: Jun 18, 2006
    Posts: 878

    53dodgekustom
    Member

    oops. Must have been thinking of something else. I think BlueSkies did his.?
     
  13. pasadenahotrod
    Joined: Feb 13, 2007
    Posts: 11,749

    pasadenahotrod
    Member
    from Texas

    Old Mopar Fan adage: Ply-Do sixes only knock once...then the bad soft crank throw pops the rod and grenades the piston.
     
  14. 6inarow
    Joined: Jan 24, 2007
    Posts: 1,793

    6inarow
    Member

  15. 39cent
    Joined: Apr 4, 2006
    Posts: 1,545

    39cent
    Member
    from socal

    My Dad, decided to trade in the ol 47 Dodge coupe, in 56. It was a fancy car in its day. In Mopar land Dodge occupied the comparable price range as a ford deluxe.It had 'fluid drive' which was a standard trans with a fluid coupling. Not the speediest car in accelration. But man what an interior , big mohair seats front and rear, was a great makeout car! It was a great hiway machine too' we cruised 65 and 70 mph and when i started to drive and my folks got enuff confidence to nap while i was driving I would sneek it up to 75 and 80 I inherited it when he traded, and it took me thru hi skool. It was a great car and i trusted it to take me whever I wanted to go , and it performed great.
     
  16. 50dodge4x4
    Joined: Aug 7, 2004
    Posts: 3,227

    50dodge4x4
    Member

    SO, have any of you guys with a built up flathead 6 ever run it through a quarter mile strip? I mean, just what kind of times/mph are you running and with what car/drivetrains? I need to know if I should hide away my "modern 6" at the drags should I come up against one with a the hot rod flathead six. Gene
     
  17. FinnishFireball
    Joined: Jan 18, 2007
    Posts: 342

    FinnishFireball
    ALLIANCE MEMBER
    1. Scandinavian HAMB'ers

  18. Mercmad
    Joined: Mar 21, 2007
    Posts: 1,389

    Mercmad
    BANNED
    from Brisvegas

    I had a '39 Plymouth with a 40 something Windsor engine( Spitfire cast into the head).pretty much a bolt ion deal.The radiator support had been reversed to allow for the extra length( I think it just unbolts and can be turned around ). There is no substitute for a few extra cubes.
     
  19. blackp-15coupe
    Joined: Mar 8, 2006
    Posts: 806

    blackp-15coupe
    Member

    <TABLE id=HB_Mail_Container height="100&#37;" cellSpacing=0 cellPadding=0 width="100%" border=0 UNSELECTABLE="on"><TBODY><TR height="100%" width="100%" UNSELECTABLE="on"><TD id=HB_Focus_Element vAlign=top width="100%" background="" height=250 UNSELECTABLE="off">Rockabilly,
    Sorry I wasn't clear the comparison is really between the 218 and 230. The difference in strength may/may not be true, that is just what i was told.
    Bugman,
    The Sharp head looks like the Fenton except there is no freeze-out plug and it says Sharp in the same location as the Fenton. I've never seen another Sharp head no one I've spoken to has seen one either. I'm curious how many were ever made. I'll try to get a picture posted as soon as I can. FYI, my friend cc'd the Fenton head and it was significantly different ( i don't have the #s handy) than the stock head on the '46 218 and he guessed at the compression ratio. The Fenton head I have is new never put on a motor. The guy I got it from brought it in 1962 and never used it or the headers and in-take which I have been trying to get from him. I got the head for $300 and I was hoping to get the other parts for about the same price. It's probaly too much to hope that I'd get everything at these prices considering a used Fenton head just sold on e-pay for $1,330.......

    Dave
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  20. Hudsonator
    Joined: Jun 19, 2005
    Posts: 335

    Hudsonator
    Member
    from Tennessee

    I haven't been down the 1/4 mile, but I have had one at full bore down the pulling track. All I can say is, tenacious.

    The crank cross-drilling is absolutely necessary if you intend on running high rpms. As is making the oil grooves in the main bearings larger to accomodate more oil flow to the rods. That is the only holdup to sustained high rpm operation in those engines.

    I haven't seen a 230 crank yet that doesn't oil #5 from the rear main or #2 from the front main, which are your two culprits for failure. You have to drill from #5 to the 3rd main and #2 from the 2nd main to fix it. I'd say that if a person widened and deepened the main bearings to accomodate more oil flow, particularly the front and rear main, you'd help the rod starvation problem - but not completely cure it. To do both the main oil grooves and cross drilling makes you nearly bulletproof - until you rev it so high you twist your crank in two.

    Stock valve springs will pull you up to 5500 rpms when new, but will start to float under no load at 5500 after a while, but will still pull 5500 under a heavy load. Neat little rev limiting characteristic, because valve float in a flathead does no damage as in an OHV.

    I really regret not spending more time on flow improvement with the 230 we built. I didn't give it much consideration as I had no faith in flatheads at the time. It taught me better and I fell in love with it after we put it on the track.

    Launch at 3200rpms, buzz it up to 5500rpms, and it would pull down to about 4700-4500 rpms at the end of hard pull on a super sticky track and never give up. The pull-down was likely a function of its cam grind more than anything else.

    The build was nothing spectacular. All stock components with the crank mods and what would be considered a slight cam increase. We did find and run the late model head, which was shaved to an unknown amount when we acquired it. Dual B&B carbs with a split stock exhaust. It ran and pulled best on 87 octane pump gas.

    It was a winner against some big cubed inlines, until the rules changed in favor of higher revving engines to catch us. I still love to get it out and hear it run, and I'm about 15-20 ft away from the pack. If the rule change hadn't brought in the 292 Chevy, we'd probably still come away with a trophy or two with the little bugger as is.

    I also know where there is room to improve over what's in the tractor right now, so it could do better than it is.

    You won't hear me badmouth the mopar 230, and most that do either haven't messed with them or don't want to. They caused me to change the way I thought, and I liked the change.

    Hud
     
  21. bbuswell
    Joined: Jul 18, 2007
    Posts: 22

    bbuswell
    Member

    Wow, that was a lot of replies in less then 24 hours… thanks guys. I thought it might have some to do with the head but when I have seen replacements for sale (like vintagepowerwagons.com) they don’t say anything about offset or year, just NOS 218/230.

    Plym 46, thanks for the thorough reply, I have been lurking on this forum for a couple of months now and have read many threads that you guys have contributed to. There is so much good info here on the hamb I can rarely think of a question that has not already been asked. Blueskies & Don Coatney’s websites has also been very helpful.

    Hkestes – I bought the exact same stuff from Tom Langdon as you did, $1200.

    As far as my build, I got the 230 engine from fellow hamber (Smokin' Joe). Cast iron headers, offy intake, carter/webber carbs, mini HEI. The engine is supposedly rebuilt but I have not pulled the head to see how much it has been shaved or the bore. My budget doesn’t allow for aluminum head or cam but I think I’m doing about everything else.

    I would like to recommend Tom Langdon as a great source. When I first called to place the order he had everything except the offy intake. I was bummed because his price was so good on it. A week later he called me and said he found an offy intake at a swap meet and sold it to me for cost because I bought all the other stuff from him.

    I also just purchased a rebuilt T-5 transmission from Tom and an adapter kit from Paul Curtis (aka pjplymouth). I almost have all my parts collected by I am still hunting for a rear-end with around 3.50 gears. It’s tough finding those gears plus 60” wide and 4 ¾ bolt pattern.

    I am going to try to make this my daily driver and am sticking with the stock suspension but will do a front disc upgrade. I get some knocking when I make a hard turns but it is better since I replaced the tie-rod ends. I have looked at the rebuild kits from Kanter but they are damn expensive. I also added a rear-sway bar I took off a late model junkyard Camero and that has helped but I am still trying to find something for the front.

    Once I get some stuff tore down I will post some pictures of my progress and will start another thread on the T-5 install to help everyone learn from my experience.
    Thanks to everyone
    Brett
     
  22. plym_46
    Joined: Sep 8, 2005
    Posts: 3,203

    plym_46
    Member
    from central NY

    Met a fellow with a 49 business coupe, built 230 engine dual carb, dual exhaust, 3 on the tree. His timing slip form the Monster MOPAR drags, started with 19. I believe road test from the time had the 0 to 60 time for a stocker at 20+. I forget what the speed was but it was north of 60. As stated, these engines even with the mods aren't real strong out of the hole, but they do shine strongly in top gear in the 40 to 75 segmant of the speedo. Drag racing applications might prosper from different gear ratios. I know with my 4.11 rear ,that low is done at about 25, and second is wrapped up tight at 45. so most of my pulling is done in high.
     
  23. Bugman
    Joined: Nov 17, 2001
    Posts: 3,485

    Bugman
    Member

    As long as we're on the subject, I'm still looking for an overdrive 3 speed trans for my '55...

    I raced my '55 against my buddy's '84 Buick 350 DIESEL(it's slower than molassas too). With around the same HP, and very close to the same weight, we always wondered who's was actually the quicker of the two. Believe it or not, with my 117 HP, I had a 12 HP advantage :D My buddy was following me and we were driving down a country road, the guy in front of me slowed to around 30 MPH to turn. I saw the opportunity to finally find out who would win and went for it. I downshifted to second and stomped on it. He instantly realized what I was doing and mashed the gas too. We were DEAD EVEN untill 60 MPH when I started to very slowly pull away(up to 65 which is the comfortable max speed for me with my 3.73's). Definitive proof! My 230 flatty is quicker than a Buick 350 diesel, even with 120 fewer CID :D :D :D

    I really should get back to the half finished aluminum head I'm designing...
     
  24. 53dodgekustom
    Joined: Jun 18, 2006
    Posts: 878

    53dodgekustom
    Member

    I raced my old 87 2.2 4cyl ECU carb. Dodge Dakota with a 5 spd (best time of 20.3 @63mph.) against my 230 53 Dodge once. My friend drove my Dakota and would get me from 0-50 but from 50-85 I would have him by a good car length or so. With 3.73 gears it was floored at 85 and Screaming!
     
  25. 39cent
    Joined: Apr 4, 2006
    Posts: 1,545

    39cent
    Member
    from socal

    having no idea that engines would blow apart from overrevving, I would just keep my foot in it! And racing one of my buddies family 48 olds 98 straight 8, which he said would gonna blow my dodge,s doors off. I kept it too the floor and at 65 the 47 dodge started to walk away from the Olds. we were all stunned! It was like it had new life!
     
  26. 39cent
    Joined: Apr 4, 2006
    Posts: 1,545

    39cent
    Member
    from socal

    Also one of my favorite cars was a 39 plymouth 2dr one of my friends acquired, and it was just a great cruiser. It had a 50 Chrysler 6 with a 37 Chrysler 3 speed OD floor shift. we went everywhere in it. And it was no slouch.
     
  27. Hudsonator
    Joined: Jun 19, 2005
    Posts: 335

    Hudsonator
    Member
    from Tennessee

    I'm enjoying the reading here, it goes right along with what I've noticed.

    I was treated to a ride in a man's '37 Dodge coupe, with a 230 in it backed by a T-5 and Camaro 3.07 rearend. Snappy little combination with legs.

    He looked at me and grinned, "watch this". We were cruising with the engine nearly at idle running 55, he leaned into the pedal and snapped us up to 85 really quick with a noticeable force putting me into my seat.

    Torquey little engines when it really counts.

    Hud
     
  28. 39cent
    Joined: Apr 4, 2006
    Posts: 1,545

    39cent
    Member
    from socal

    ohh one more mopar story, [all true of course], Another friend had a 49 Plymouth 4dr, it had a chrysler 6 and 37 od floorshifter. Nice blu paint unfortunately bad body prep, with waves all over. He had a name painted on rear windows "ocean motion". For the waves and the way the engine rocked at idle. It had some kinda 'ISKY' cam in it with 2 carbs. not much bottom end but it would really pull when it got some revs.It got a pretty good time at Colton Dragstrip, really surprised us, as did a lotta flathead Ford guys especially cruising or rolling starts. His specialty was fakin guys out by offering to race for "pinks" while the old 6 was loping at idle, it sounded so bad ass that they wudnt race him, ggggg we had lotta fun with it.
     
  29. RichFox
    Joined: Dec 3, 2006
    Posts: 6,624

    RichFox
    ALLIANCE MEMBER

    I remember an old guy telling me that the oil passages from the main oil gallery to the cam were the same size as the passages to the crank. He told me that you should restrict the oil to the cam bearings to improve the oil to the crank. Seemed reasonable, but I never stepped up from the 4 to a 6 so I don't know. What do you think?
     
  30. mtkawboy
    Joined: Feb 12, 2007
    Posts: 1,041

    mtkawboy
    Member

    A good source for flathead Plymouth/Dodge parts is an old forklift junk yard. In the Air Force and after I got out I used to rebuild engines for them. Most forklift shops have their own junk yards out back. Might be worth a try anyway
     

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