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Technical Flatty Offset grind

Discussion in 'Traditional Hot Rods' started by Beecher, Jan 28, 2014.

  1. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    Okay, Okay, Im nuts. I know.

    But it has always been a dream on mine, to build a "Merc bore 1/8 stroke" motor. Im finally building another flatty, and its a prewar build. Using a 40 block (had a 39 merc, but she had some cracks), this block actually came out of my 40.

    Anyway, i want to take a later crank, and offset grind it to take floaters and 1/8 stroke it. I know for the same money i could get a 4 incher, but its not what I want. Is there any serious issues with offset grinding them, or so long as its done well, all is good? Ive got a shop lined up to do it, they grind lots of flatty cranks, tho i never asked if they ever did this, but I told them what I wanted to do, and he went away for a few minutes, and came back with a price, so it didnt seem to bother them. Is there anything I should be specific about getting them to do when they do it.

    I also seen some reference to needing a different rear main seal retainer?

    Any suggestions? Anyone done it recently?

    Thanks so much

    Beech
     
  2. flatcat
    Joined: Nov 16, 2013
    Posts: 45

    flatcat
    Member

    probably easier and cheaper to buy a scat crank. 4-1/8 or 4-1/4" stroke. I just finished a 3-3/8 bore by 4-1/4" stroke for a fellow with no real issues. All scat.
     
  3. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    not really. I dont want a 4 plus inch stroke crank. I really want a 3 7/8, and if that doesnt pan out, ill stick to 3 3/4. No one has any experience with one? same goes for a 4 incher stroked out to 4 1/8 too, anyone with experience on that?

    thanks
     
  4. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    Early rods and floater bearings are a bitch to set up properly when you can find the right parts and someone who knows how. You're far better off if you offset grind to use the SCAT rods at least - they use off-the-shelf bearings from Buick V6 (I think). Easier, cheaper, and easier (yes, I said that twice).

    I have a 4" crank I plan to offset grind 1/8" on my next build, but it's on hold for now...
     

  5. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    3 7/8 was once the only cheap stroker...early Merc crank offset ground to Ford 221 rod size. You do need one that is not too far under standard to have enough room to reach the smaller size and still be able to use available bearings...get everything measured by the machinest who will do the job and purchase bearings before you start grinding, as bearing availability is getting spotty.
    Rear seal...there are pot metal inserts at back that need to match your crank. Most prewar cranks used a slinger that lived in a narrow groove in the inserts, postwar used a rope seal and inserts with wider slot to hold the rope.
    Pistons for normal fit would be custom, but you might want to think about pop-up and slight flycutting of head when engine goes together. Get a tight custom fit in quench area.
    The floater bearings and rods have theoretical superiority to locked bearings, especially in high RPM use, but this is not much of a concern on normal levels of hop up. For race use rods have to be much beefier for high RPM use with locked bearings.
    Get hold of Ron Holleran's book over on Fordbarn...good clear directions on setup of floaters. If they are not right as made, you need to purchase some expensive engineering tools, namely a rubber mallet and a foot or so of pine 2X4, to custom fit the curve.
     
  6. alchemy
    Joined: Sep 27, 2002
    Posts: 17,280

    alchemy
    ALLIANCE MEMBER

    Are you using the Merc crank for cost reasons? If so, I bet you will blow all that savings plus more on the custom pistons needed for the 3-7/8" stroke. Can't see why anybody would keep those on the shelf anymore. A 4-1/8" stroke is a bit more common, but might still require a custom piston if you have an odd bore.

    I've got a few sets of standard and .010 bearings, and 21A rods, stashed away for doing the 4-1/8" stroke on my motors. I pick up Merc cranks for reasonable prices (doesn't happen very often any more) when I can.
     
  7. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    thanks guys! I did see you could get cranks made from scat in either journal size, I hadnt looked into the rods choices yet. If they make ones that take later bearings, that would be perfect.

    Cost, to me, is about the same as a 4 incher, i can get my hands on usable at std 8ba cranks to start with, and its only about 50 extra bucks for the pistons from ross, and I planned on ross pistons anyway, so thats not an issue. The additional cost of the offset is about the same as buying a merc 4 incher core. My engine builder and I decided that if a std crank was offset, we should be able to wind up at std size on the offset, which seem to be fairly easy to come by, and the same price as a set of inserts, and if I REALLY had to, seems Reds headers is making brand new .010 unders at 450 a set, which, if thats what it came down to, id skip it, and stay at 3 3/4. The scat 4 inch crank is a few hundred more.

    A question on the scat rods, I have heard they require some clearencing, even on a 276er. This motor is going to be a stock bore 3 3/16, how much clearencing would be needed, im not sure where the work needs to be done.

    The very long story is that I had always wanted to build a perfect pre war gow job, which is what im doing now, so 4 incher, historically, would be very rare and unlikely, while the 3 7/8 seems almost common. Since I knew this would be a merc bore motor, and no one listed stock bore forged pistons, I figured I was in for custom pistons anyway, which is why I went down this road. When I phoned Ross, I found out they still made them, just no one listed them, but by that time pistons where about the last thing I needed to find out about for this stroker. By the time all was said and done, the 1/8 stroke I always wanted was not any more than a 4 incher. I just wanted to see if there was any obvious objections by those that did it, or advise from those that do, such and ensuring a certain radius be put on the journals or something. Im about 99% sure it will go the 1/8 stroke, not cause it makes sense, but its what I want, provided its not enherently risky about it. If I was after quick and easy, I wouldnt be running 4 winfields!

    I know I could just put a 4 incher in it, and lie about it, but I do this because it makes me happy, and the 4incher really wouldnt make me happy, it would always be the chink in the armour of my "circa '39 build". Im strange, I know.....

    Thanks guys, any input on actually doing it would be greatly appreciated.
     
  8. CNC-Dude
    Joined: Nov 23, 2007
    Posts: 954

    CNC-Dude
    Member

    Other than the issues with having to use the "common bearing" rods and possible longevity issues in them with today's elevated HP potential compared to yesteryear, I would at least opt for the Scat rod as the platform to build from.
     
  9. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    It doesn't really pay to offset grind the cranks anymore, the parts are readily available and I personally would go direct to the 4.250" stroke and never look back!

    We are in the process of putting about 5 kits together tonight, am waiting on the Ross pistons. I wll say one of these kits is the 4.125". Customer choice??

    We use the Eagle cranks, the Scat rods (2.000" Pontiac/Buick journals) and Ross pistons with their "metric" ring pack. The Eagle shafts balance up much better than the Scat's. The kits come with the main brgs included!

    We will be changing over to Comp Cams for the cam, in the past it's been Isky. Comp will make them to our specs. Most get either Edelbrock (large chambers) or Offenhauser heads also!

    Thanks, Gary in N.Y.

    P.S. If you click on the link below here you can read about a build that was done a few years back. Has over 12,000 trouble-free miles on it now. Made over 150 HP and over 260# Torque.
     

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  10. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    Timely inquiry. Over on Fordbarn there was a similar question:

    http://www.fordbarn.com/forum/showthread.php?t=128501

    General consensus seemed to be the older CAT rods had clearance issues, but current scat rods don't....ymmv. Check anyway!! Always!!
     
  11. flatoz
    Joined: May 11, 2003
    Posts: 3,201

    flatoz
    Member

    A couple of things, and bear with me on this , just some stuff to mull over.

    IF you go the scat rods with your 3 7/8 offset crank, then your being a bit hypocritical as you won't use a 4" because it doesn't fit in with your pre or around 39 build date as such ( but then neither do the tires as they will be new or the radiator hoses etc... can go on and on)

    I would suggest you get hold of a set of the french rods that Vern Tardel sells, if he still has them, at least they are flathead rods, while again they are later in manufacture but they look like a flathead rod because for all intensive purposes they are.

    As to , do they fit year wise, well that will have to be your call.

    As to will they do the job, I would say yes. I have a set of OLD 8BA rods in my motor I did have them reconditioned by a guy who's anal on getting rods' right, and while not a stroker motor, I do have a 4/71 ontop of my motor and I think that would put more stress on those old ford rods than you 3 7/8 stroker will. So I wouldn't be worried on using for rods is basically what I'm saying

    But to do that you would need your guy to be happy to build up the crank so you can use the ford rod diamter as in 8BA style instead of the full floating.

    I understand your thought process on it, sometimes we want what we want good or bad and thats cool at the end of the day as odd as it sounds I can see that you would be dissapointed if you ended up with a 4" as its not what you wanted, and if these cars are nothing, they are an extension of what it is we like and our personalities and visions.

    I think its great you have a machine guy who's willing to work with you on this, I would think that would be the hardest part of all this.

    Can't wait to see the motor.
     
  12. jambottle
    Joined: Apr 11, 2003
    Posts: 564

    jambottle
    Member

    what is the ballpart price for eagle crank,(4.25)scat rods(buick bearings and ross pistons ,rings and crank bearings. Thanks
     
  13. alchemy
    Joined: Sep 27, 2002
    Posts: 17,280

    alchemy
    ALLIANCE MEMBER


    This all doesn't jibe. You want a "perfect pre war gow job", but are willing to use Scat parts? I'm done here, sorry I wasted my time.
     
  14. 21stud
    Joined: Sep 3, 2006
    Posts: 281

    21stud
    Member
    from California

    Period gaskets,sealant, bolts, chrome, weather seals, paint, Bondo? , lead, tires, hoses, water, battery?, sandpaper, bearings. Just build it and drive it. I think some of you are on your period.
     
  15. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    I agree. I never claimed it had to be all original parts, just that a 4 inch stroke was fundamentally wrong for the build, be it eagle, scat or ford.
     
  16. 21stud
    Joined: Sep 3, 2006
    Posts: 281

    21stud
    Member
    from California

    Beecher. I know. No problem. I think its a lot of work. ( probably money too). I know we all know the value of bragging rights and wow factor.
    Most of us don't put a no name cam in our engines.
    I have to put this in with the port,polish ,relieving. A lot of work for going to car shows and the local hang out. Each to their own. What are you going to use the engine for?
     
    Last edited: Feb 1, 2014
  17. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    Just a "heads-up" guy's, but neither the Eagle nor the Scat's are going to "fly" with any std bore (3.190") Flathead bore!!

    Simply put, they WILL NOT pass through the bores for ass'y!

    I'm talking about the 2.000" rod brg rods here, the "span" across the face of the large ends on the Eagle brand is 3.200" and the Scat is 3.228", they will not go in. The Eagles would need a +020" (minimum) overbore and the Scats would need a +.040" minimum, and these would still be a very close fit?

    Thanks, Gary in N.Y.

    P.S. I am waiting for some dimensions on the "conventional" Flathead rods from Eagle and Scat with the 2.138" journal, but I would "go-out-on-a-limb" and say they are most likely NOT any narrower due to the larger brg required?? Just a guess right now.
     
    Last edited: Jan 31, 2014
  18. flatcat
    Joined: Nov 16, 2013
    Posts: 45

    flatcat
    Member

    Gary (go fast) I remember discussing your possible purchase of blocks about 12 years ago and you were setting up shop. I am amazed how far you have progressed in such a short time. Keep up the good work. Bill
     
  19. 21stud
    Joined: Sep 3, 2006
    Posts: 281

    21stud
    Member
    from California

    What is this engine going into?
     
  20. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    I was worried they might not fit! Flatty rods are squiffy at best to recondition anyway, because only the cap can be milled, so i thought I might splurg on the rods, I could install them other way round, but that doesnt sound like a lot of fun either.

    Its going in a highboy (for now) 28A roadster, but full fenders down the line. With this motor in it.

    http://www.jalopyjournal.com/forum/showthread.php?t=812685

    Its a 21A block (found a 99, but turned out to be cracked), 39 top loader, but rearend year is to be deteremind. I have one of every year pretty well. Ideally, Id use a 34, but they might be too far gone to really use, so probably a 40, possibly not even narrowed. Basic formula, but the motor is going to stand out a bit.
     
  21. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    My biggest concern really, is the full floater bearings, I am waiting to see from a couple sources, but many I have seen (and all that i have) have gone "bad" where the bearing surface is no longer shinny, but oxidized and gone dull, some say it doesnt matter, some say it does, Im in the rather safe than sorry camp. I could spend huge and get reds new .010 unders, but I dont want to go any MORE under. I like the idea of new rods, and new easy to find bearings. I have no issues whatso ever making the full floaters work, Id rather run them to be honest, Im just having reservations about the age of some of them. Id rather run NOS rods then reconditioned as well, but we cant always get what we want. At least right now, Im on an ignition kick, so my mind if off the crank. Trying to get a zephyr converted (A monster of a project that is). And I have to do some pattern work this week too. And midterms next week... wahhhhhhhh sorry, just venting now.
     
  22. This is not a big deal - as long as you have somebody who knows how to setup the full-floater bearings, rebuild the rods and get the clearances right.

    Since you'll be offset grinding a 3 3/4 stroke crank, you'll end up with a STD journal size - which are the easiest to find bearings for. I'd run a set of 21A or 91A rods, have them shot-peened, straightened, rebushed, rebuilt, etc.. There is no way you're going to hurt those rods in the engine you've described - so why even think about the SCAT rods (other than they are far easier to setup!). If you want a pre-war build, then make a pre-war build . . . or say screw it and bore it big, put late model stuff in it and have a large cube motor.

    I'm building a pre-war style 1942 Merc engine as I write this . . . and I'm doing everything as period as I can (but I will have a 4 1/8 stroke late Merc crank in it - as I like the cubes). Also, I'm building a 'new' Lincoln V-12 converted distributor - as that was about all that was available at that time and I decided I wanted to convert one - to learn the details (is a complex PITA :rolleyes:).

    I know - screwed up in the head . . . but I want it a certain way, so I'll build it a certain way.

    Here is a set of the bearings you need - and they are the better cad-nickle varieties (which I like)

    http://www.ebay.com/itm/CONNECTING-...Parts_Accessories&hash=item4d1325fbed&vxp=mtr

    Also, you might call 'Little Dearborn' on rods - they may still have NOS 21A rods.


    If you need any additional information, just ping me.

    Here is the heads/manifold and block on the stand. Just found a crack in the chamber of the heads - hope I can fix it! Wanted the old Eddie Meyer stuff.

    1942Engine-For32Cabriolet copy.jpg
     
    Last edited: Feb 3, 2014
  23. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    you are as sick as me. I got 2 v12 tore apart on the table now, also trying to reinvent the wheel on that one. Think Ive got most of it done in theory, now to go make the parts.
     
  24. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    I just rediscovered a source I had forgotten about..Ocee Ritch's Lincoln Continental book, which has not only a reprint of the overhaul manual but an interesting soup-up section with some numbers. Pretty easy to find in used book hunting.
     
  25. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    That would be an interesting read!

    Oh, and I love the early eddie meyer heads, one of my favourites
     
  26. 21stud
    Joined: Sep 3, 2006
    Posts: 281

    21stud
    Member
    from California

    Let me know if you need help setting up your Winfields , when the time comes.
     

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  27. Beecher
    Joined: Jan 28, 2004
    Posts: 159

    Beecher
    Member

    beautiful! I think I have another pic of your motor around! thanks, im sure Ill need it!
     
  28. 21stud
    Joined: Sep 3, 2006
    Posts: 281

    21stud
    Member
    from California

    No problem. I had a set on my roadster also. They work great if set up correctly.
     

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