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Mopar flathead 6 motors- whats to be expected

Discussion in 'The Hokey Ass Message Board' started by Modeljunkie, Dec 8, 2011.

  1. Now you guys have me thinking about that 48 Chrysler Windsor I picked up a couple of years ago.
     

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  2. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,924

    hillbilly4008
    Member
    from Rome NY

    I love the 251 in my Desoto, with a little bit of work done(milled head, split manifold, 2" pipes with Porters) to it I can cruise at 65-70mph easily. I still run the "clunk-a-matic" transmission in my car, thats robbing quite a bit of power.
    [​IMG]

    Plym_46 has a real goer in his car, he was kind enough to let me drive it one day. Great car
     
  3. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Actually, right there did...unless your saying that the fluid drive was one of the means of torque transfer aside from the earlier simple clutch only units....they had a later hydromatic that was a semi auto trans- one had to clutch to go between reverse or drive {or vise versa} but that was it. That was just a 2 speed too...right?

    As far as the motors go I think I got it...a 201 can be made into a 218 with the 218 crank and rods, and 218 can be made into a 230 with the 230 crank and rods...and all of those were the 23" block-
    -Canuck cars, desoto and chrysler followed a longer motor path via the 25" blocks.
    Crank bolt patterns were dependant on specific group years, makes and trans' as well.
    Not having crawled under the car as of yet, I thought I heard these motor/trans combos had 5 point mounts- 2 front of the block, 2 mid at the trans case and 1 at the tail by the parking brake. If this is correct, can these motor/trans' be supported via the 2 front and tail only like modern engine/trans combos...and whether it's wise to do so as well if the bellhousing can take that kind of strain.
     
  4. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Ok, let's talk block mods now;
    - can larger valve/valve seats be added to aid in breathability...and along those lines can intake and exhaust ports be ported or cleaned up better?
    - can new cams be had or do we have to regrind the ones we have?
    - Which is better to install- aluminum pistons or cast iron...or is there no real choice there pending block/year?
    - aside from the "next motor size up crank/rod increase combos" out there, are there any other ways to offset grind the cranks and/or use other rods and pistons{different pin heights} to make more ponies or cubes..how much has anyone experimented with these..or is it not worth it?
    Reason I ask is that my buddy was into the mid 60s 215 olds aluminum blocks and with the right crank with offset grind, different rods and pistons one could hit 300 cubes...sorry this is the wrong motor to bring up in this thread but it's the general premis that I'm after for our flathead 6 motors.
    -lastly, for now, can anyone lead myself and any of the other readers here to a chart that would show a flathead 6s' stock or modded torque and HP ratings on a graph to see where the HP tapers off at...I can only imagine the torque line is a continuious path from idle on up. I hear redline is 3600 to 3800, so I'd like to try and find really where the end of the usability rope there is...anyone who's ever modded a motor knows that if a given motor's set up Hp rating drops considerably at, say, 5600 and torque drops off at 5800...you need to shift or stay at the span of those two or the motor is just making noise..yes, I know the 6 would grenade at those specs, it was just an out of thin air reference.

    Thank you for all the input so far...I greatly appreciate it!!!
     
  5. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    I'm including a few pics of my application{car} for those ho may have a similar set up-
    Here's a general view of the engine compartment- this is a 40 plymouth
    [​IMG]
    Here's the block, a 201 and yes I have the oil bath air cleaner, it's just the PO had a loose fitting nut on it and I have to take the whole thing into ace harware today to get the correct fitting nut for the air cleaner.
    [​IMG]
    Here's the front of the radiator bulkhead, there is some fudge room available for moving it forward and the PO gave me a spare panel {top nose piece} to possibly aid in the event if I ever did.
    [​IMG]
    You later model guys have it easier with your one piece hoods, mine is two piece and easy lets rain in/on the top of the block which is a minor hassle for puddles around the plug holes....everything is a trade off I guess as I really like the twin hood halves.
     
  6. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    In case your wondering, the rope was useful to hold the driver's door open while I pulled the speedo the other day...tacky but effective.

    Sparkplugs- what's the choices here- I got a set of champion RJ12YC since that's what was in there before...the parts counter guy tried to give me a set of RJ12C but the reach was wrong...same guy had to be told, "yes, 1940!" for the 3rd time since he obviously didn't believe me the 1st two times...ah young kids.

    Gotta go look up a replacement oil filter now...a WIX unit...
     
  7. krooser
    Joined: Jul 25, 2004
    Posts: 4,584

    krooser
    Member

    These are really neat old motors....
     
  8. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    Most folks like AC 45's they start better than the Champs which should be J8 or J8C the 12 are a hotter plug with an extended tip which is not a good idea as the plug sits over a valve. Be carful withthe valve area, they are equiped with hardened seats (exhaust) from the factory, as such your engine will ru uleaded just fine thank you very much.

    As far as cams are concerned, again a long stroke motor, so not really needed unless you are going for high revs. Easy to match the ports to the gasket by doing a bit of grinding and cleaning up. the best bang for the buck with these is compression. Infact one of the things folks have done is run the 201 heads on the large blocks as they have a smaller Combustion chamber area.

    Go to carnut.com and check the specs area. It is easy to see that during the years of production the HP ratings went up in conjunction with marked increases in compression ratio. On the dodge side the 50 230 was rated at 103 HP at 7 to 1, in 54 this went to 110 with an increas to 7.25 to 1 in 56 at 8 to 1 the HP was 135. So same carb, same pistons, same cam, more HP.

    As far as offset grinds, and other exotic stuff, not really effective cost vs gain.

    Lighten and rebalance the flywheel, do a bore, mill the head deck the block, open up the ports, if you want to cross drill the crank, open up the exhust, and add some carburation and you will have a tractable and reliable street engine.

    The transmission is bolted to the bellhousing with 4 bolts, and hangs there defying gravity. The bell sits on 2 rather large and stout steel and rubber mounts through a crossmember, the front of the engine sits on a laminated rubber isolator bolted to a sheet metal assembly that bolts to the frame. So the engine is hanging at the front and sitting on the crossmember at the rear.

    Your oil filter is a sealed disposable canister that are nolonger being made. there are some out there but they go for stupid high money. You can pick up the style with replaceble drop i elements for 25 bucks and up. In the mean time leave what you have (the factory replacement replacement was 7k miles) till you can find the other style. the other cans will fit in the existing braket, you may need to alter the plumbing a bit, as some feed line go on top and some on the side.

    This thead may be of interest to you

    http://www430.pair.com/p15d24/mopar_forum/showthread.php?t=24666

    Would suggest you check out the information available at P15 D24, site and the forum there, as your car is mechanically similar to the later models.
     
    Richard Hartman and 52RAM108 like this.
  9. exterminator
    Joined: Apr 21, 2006
    Posts: 1,695

    exterminator
    Member

    I removed my stock engine because i am use to newer engines in my cars and the starting from stop to go was too much for me to bare.By the way i still have that engine and trans if someone is interested. Exterminator
     
  10. 73RR
    Joined: Jan 29, 2007
    Posts: 7,175

    73RR
    Member

    I would not recommend such a mounting system. These engine are long and heavy.
    There are an ample number of exposed/useful fasteners at the back of the block that can be used for attaching mounts. My adapter is thick enough that one could even drill&tap into the side to affix mounts if needed. If you want to change to a modern transmission then plan on some fab work. Even if you use a Plymouth bell and mount something like a Ranger/Mazda 5-speed the oem mounts are not likely to be in the same place as the fluid drive. I don't have samples of each to compare so maybe Plym 46 can opine.

    As to increased power production, I would buy a forged piston and leave everything else alone. All of the 'small' expenses will add up so why not just make one purchase?
    As to offset grinding, do you really want to make a 4.6" stroke bigger???:eek:

    Allpar has some additional info: http://www.allpar.com/mopar/flat.html

    .
     
    Last edited: Dec 11, 2011
  11. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    There are 2 fairly comprhensive threads on P15 D 25 forum regarding 5 speeds. One using a S10 sourced one, and a more recent one regarding the Mazda/Ford, box, niether using adapters but rather modifying the bellhousing. Some have also mentioned using the mopar A833 from 70's volare/aspen, and light duty trucks and vans, another possibility is the Toyota supra 5 speed and the Dakota Jeep sourced Boxes. All OD units.

    Others have swaped lower geared rears from Rangers, Exploreres early Cherokees Dakotas Early B bodies etc. for more relaxed cruising RPM.

    Me, just tall tires, stock trans and 4.11 rear.

    I would recommend getting yours running driving and stopping, and then do your evaluation based on real world experience. Do you really need 200+hp in a car with 10 inch drum brakes and a single pot MC???

    The KISS process seems to be the most viable for these engines unless you are building for all out HP, which is wasted for street driving.
     
    svnbz likes this.
  12. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Just went out and did a compression test on the block to see where I'm at, speedo shows 79k...could be 179k.
    Ten cycles of rotation of the starter, all plugs out-
    1-45
    2-75
    3-70
    4-65
    5-75
    6-70

    added some oil to #1 and redid, she came in at 55 this time.
    Hmm, a rebuild seems inevitable.
     
  13. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    1)I registered @ p15-d24 but the problem is I put in for it rather early in the morning{1am ish}, didn't have the foresite to write down the user name I got approved at because I expected an email confirmation with that...bad and wrong! Sent them an email asking for the user name/pass...untill it comes I can only watch.
    2)working on that 1st of course....the sloppy shifter linkage is next up on the list!
    3)no, around 120-130ish would be fine for my needs and current braking! Even if I swapped to front discs there'd be the limited amount of expected HP from the motor...I want to simply improve upon it alittle more than what she's got now, not blow it up. My 1st request for 150 was blind wish list, but now understanding the motor better I see that's pie in the sky.
     
  14. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    Have seen lots of these engines run on 75 lbs of compression. A couple of guys from western Canada mad a trip through the states to Hershey and back in a 47 Plymouth that had only slightly better compression when they set out. My guess would be you have a valve sticking on #1. It may free up after you get some heat into it, or you may need to pull the head to deal with it. Whe you get it running you may find that a vacuum gauge reading will give you a better picture of its internal condition. You may be able to free up the valve throughthe side cover under the exhaust manifold. There should be an access panel in the inner fender that will give you access. Some times you can wedge the spring and or turn it to get the valve to free up or seal better.

    By the way post the engine number. Its on a boss on the block just under the head above the genny. With the ease of engine swaps on these cars it may not have its stock motor. The stock series number should start with a P10 (the engineering code for the series) then additional digits.

    The webmaster on P15 D24 is a one man show. Some times it takes 48 hours or so to get an e mail confirmation. Mean while, go to the main page that hosts the forum and read the stuff that is there.

    150 at the flywheel is not out of question for a 230.
     
    Last edited: Dec 11, 2011
  15. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Block #P10 149532 / head #11208003-3 11/29


    Oh, been doing that alot already..I want to be able to post though...good things are worth waiting for I guess...nice to be hear as usual in the meantime!{not that I plan to leave when registered there}
     
  16. Re cams for these motors, I'd check with Earl Edgerton (Edgy Cams). I had him regrind a cam for the engine in my '39 Ply coupe (see my avatar). He offers severl grinds. He is the guy to talk to re hopping up these motors. My engine is '55 Dodge 230, bored .060, Egge pistons, Langdon headers, Edmunds intake w/2 Carter carbs, re-worked distributor. The engine was an automatic (with 8 bolt pattern on crank) so we re-drilled the stock Ply flywheel so I could keep the Ply driveline.
    If you do some searching you'll find a lot of after-mrket stuff for these motors.
     
  17. I forgot to mention - if you want to go for the big bucks and have something really exotic - Earl Edgerton makes an overhead valve conversion for these motors. If memory serves the complete kit (head, valve covers, cam, lifters, rockers, timing cover/chain, etc) runs about $5k. I saw this mentioned on a thread here a while back.
     
  18. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Ooooh, I just checked Earl's site out, nice stuff! I didn't see anything there about pistons or OHV conversions....but the intake manifold and heads were darn nice!
     
  19. hkestes
    Joined: May 19, 2007
    Posts: 585

    hkestes
    Member

    Bad thing about the 25 inch engines is that there is limited speed equipment available for the larger engines.

    Earl Edgerton (Edgy Speed Shop) also builds new finned aluminum heads.

    Here is my 57 model 0.30 over 230 with Edgy Speed Shop head, offenhauser intake, Repop Fenton cast iron headers, Carter Webber 2bbl carbs and a mini HEI distributor. Backed by a 53 model OD trans and stock 4.10 gears. All in a 48 Plymouth Club Coupe.

    Cruises at 70 with no problems.

    [​IMG]

    [​IMG]
     
    Zandoz likes this.
  20. Weasel
    Joined: Dec 30, 2007
    Posts: 6,698

    Weasel
    Member

    Here are some porno pix for ya - including Earl Edgy's F-head conversion....

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
  21. 73RR
    Joined: Jan 29, 2007
    Posts: 7,175

    73RR
    Member

    At this point, George Asche needs to get mentioned...814.354.2621

    You have free long distance on your cell phone, use it!

    .
     
  22. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    RichFox
    Member Emeritus

    I have seen the F head conversion on Earl's truck. I may be wrong but I think it is only made for Chrysler/DeSoto engines.
     
  23. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    A bit of a caution, a short call to George usualy last about a hour.
     
  24. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    73RR, can you machine in dog ears for rear engine mounts when you cut out the flathead 6 adaptor plate?!...anyone ever do this?
     
  25. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    At the risk of sounding stupid, who's george asche?


    Question folks, concerning oil filters for these flathead 6s, I have the Wix #51035 toss canister on right now...what can I do for a remote screw on filter set up for ease of changing - how do you guys do it?
     
  26. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    Getting off subject for a moment, what do you mid 40 model year guys have for trans linkage...cable and rod like mine? My shift rods are really bad{loose} and the cable is not set right, hard to get from the front sector to the back{R-1/2-3}. Wish they made floor shifters for this set up....really.{I'd be in the minority on this, I'm sure}
     
  27. Modeljunkie
    Joined: Sep 25, 2011
    Posts: 279

    Modeljunkie
    Member

    hkestes- how much did that edgy head and manifold set you back?
    Is that mini hei from the stovebolt site?


    I wish ma mopar would've made a 1 wire alternator...
     
  28. plym_46
    Joined: Sep 8, 2005
    Posts: 4,018

    plym_46
    Member
    from central NY

    George is the recognized authority on MOPAR L 6 motors, he splits manifolds, rebuilds over drives, remans B ad B carbs, etc. Used to race the flatties for years in Western PA.

    Your shift linkage is different from the post war cars, so I can't help you, but the transmissions are selector style. Check the rubber gromets at the steering column, and make sure the movement of the levers goes freely from detent to detent.

    Also check the condition of the front and rear motor mounts as if they are squashed and sloopy they will cause the linkage to travel more than they should.
     
  29. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,924

    hillbilly4008
    Member
    from Rome NY

    When I got my car it had sat since 1976. I got it running the day I got it home. I thought it sounded great, real strong motor I thought. I took it for a quick spin, you know the kind when you just gotta see how she runs but you don't yet have brakes;) She barely had enough power to make it back on her own. I thought it had something to do with the M6 tranny.

    Some time later a Rcranger was at my shop and I started it up so he could hear it run. He tells me theres something seriously wrong with my motor, almost like its skipping. Honestly I couldn't hear it. We pulled the plugs and just held a thumb over the holes to check compression. Sure enough I was only running on four out of six cylinders. Off comes the head, and we find out that the exhaust valves on the center two cylinders were stuck open.

    Once we got those freed up I did the MMO treatment and its been fine ever since. After all this I found a note pad in the car showing all the service records. "engine job - 72,000miles" The car had 74,000 miles on it when I got it, and here I was thinking "wow, that Marvel Mystery Oil is really great stuff!!!"
     
    Latigo likes this.
  30. hillbilly4008
    Joined: Feb 13, 2009
    Posts: 2,924

    hillbilly4008
    Member
    from Rome NY

    Be prepared to have a LOOOONNNGGG conversation. He likes to talk. Great guy
     
    52RAM108 likes this.

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