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Technical Flathead crankshaft and stroke

Discussion in 'Traditional Hot Rods' started by gotit, Mar 6, 2014.

  1. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member

    So I am getting ready to start the rebuild of my 59AB for my car and I was looking for advice from people that have done it. I was going to go 276 CID with ross pistons, eagle crank, an isky 400jr cam, stock size proflo valves, zephyr springs, 8ba rods, edelbrock heads and an edelbrock regular 2 pot manifold.

    The more I think about it the more I ask myself why I I wouldn't go for the longer stroke, like the 4.125 or 4.25. This engine is in a 48 sedan, so it's a heavier car.

    I've also done a search and have come up with mixed reviews but what are the opinions on crankshafts? Is eagle ok or should I stick with scat?

    I am ready to order parts so any advice is welcome.

    Thank you......GotIt
     
  2. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    Somewhere on here people are bitching about the aftermarket cranks. Don't know why. And I'm not smart enough to find the link.


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  3. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    Maybe it was the entire kit??


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  4. Can't give you any advise on the on the 4.125 or 4.25 crank options, but the engine in my 32 coupe is a 276. Running a 4" Merc crank, :125 over Isky 400 cam, 8ba rods and running 4 x 2 97 carbs, I am really happy with it runs very strong.
     
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  5. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    We sell a number of these kits, Eagle (4.25)" crank, Scat rods, and the Ross (3.312") pistons with the 1.5, 1.5, 3.0 metric ring pack.

    We also keep the 4.125" for guys that want this setup.

    We like the smaller rod brg size, this kit uses the Pontiac/Buick (CB610P) rod brgs, and with the Scat rods there is no "clearancing" required to clear the lower bores. I know the factory rods clear also but the H-beams are a much better piece and all is new. No rod resizing, no pin bushing replacing!

    If you click on the link below the photos you can read about a build that worked out real well, had some high-end mods performed, 95% oil filtering, heads/gaskets "pinned" to block, same setup as SBC with 5/16" doweling. (See photos below)

    Thanks, Gary in N.Y.

    P.S. We do all our own balancing in-house, the Eagle cranks balance up easier! That build should produce about 150 HP, but would require the metric rings! Here's a shot of the Eagle 4.250" crank, the oil filter mod, and the pinned block/heads. We feel this is very important with aluminum heads, it helps extend head gasket life.
     

    Attached Files:

  6. flat286
    Joined: Aug 18, 2013
    Posts: 19

    flat286
    Member
    from Indiana

    I would much rather keep boring down on old cylinder walls and go with a longer stroke . I like the 4 1/8 by 3 5/16. Build just finished two.

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  7. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    I'm with you on the Merc crank. That's what I have with a 3/4 cam.


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  8. flathead4d
    Joined: Oct 24, 2005
    Posts: 889

    flathead4d
    Member

    Is that extra 1/8" stroke going to give you any appreciable difference? Maybe so on an engine you are going to race but for a regular driver or occasional strip run, I would go with the 4" Merc crank. It's a whole lot cheaper and less work.
     
  9. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member

    All good information. Thank you guys very much.

    Cully33
    That's good to know. I've been set on a 276 for a while

    GOSFAST
    Do you have to drill the gasket for the dowel pin? If so do you use copper or the graphtite? I will talk to my Machinest about doing the dowels. I am going to do the metric ring pack no matter what displacement I take this to

    Do you sell parts?

    Thanks for all the good information
     
  10. Russco
    Joined: Nov 27, 2005
    Posts: 4,194

    Russco
    Member
    from Central IL

    I used a Scat crank , rods and Ross piston kit it 4.125 stroke x 3.3125 (284 CI) it was very nice and with a 1007b grind cam the thing was pretty strong bottom midrange a great street flathead motor. One thing to check though is the dome on the Ross pistons matching the profile of the head chambers you are using, you have to check the clearance for the entire dome not just the center. Don't ask me how I know that.
     
    Last edited: Mar 6, 2014
  11. flat286
    Joined: Aug 18, 2013
    Posts: 19

    flat286
    Member
    from Indiana

    Where are you guys finding these 4 inch cranks. Around here its a lot easier to find chicken lips.

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  12. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member

    So it looks like the only pistons available for the. 4.250 stroke is the 3.375. That's too much bore for me. I want to stay at the 3.3125 bore.
     
  13. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    You know, you have a good point. I looked on eBay for shits and only found the early ones.


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  14. J'st Wandering
    Joined: Jan 28, 2004
    Posts: 1,772

    J'st Wandering
    Member

    I have found them in Mercury motors. I have also found them at swap meets. I bought one either from here or e-bay, can not remember. I find them for $200 to $300. I buy them at $200.

    Neal

    Posted using my typing skills I learned in school. No app needed.
     
  15. flat286
    Joined: Aug 18, 2013
    Posts: 19

    flat286
    Member
    from Indiana

    Yea but if you find one for 200 then you grind and polish you almost have as much in it as a new crank, and for about the same money you can get a 4 1/8 over a new 4 inch.. Not really into 4 2/5 ..


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  16. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    I sent mine out and had 300$ easy in it. Ports are important. Point made. But I also removed aftermarket head studs and thru them in the trash and bought original head bolt on eBay. Something said for original stuff. Just nowadays aftermarket shit isn't that good. My 2 cents


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  17. J'st Wandering
    Joined: Jan 28, 2004
    Posts: 1,772

    J'st Wandering
    Member

    I did not say my purchases are the best deals. You asked where I find them. :)

    Now we know why there is still value in those old cranks and also why they sell the new ones. Everyone is happy in the end.

    Neal
     
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  18. flat286
    Joined: Aug 18, 2013
    Posts: 19

    flat286
    Member
    from Indiana

    I'm with you there .. I wish I had a barn full of 4 inch cranks. But I don't . And I drag raced a big block Chev for years with a scat crank in it . So I wasn't afraid to use them. I m glad they make them..I'm happy we can keep are old flatly,s going strong..


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  19. dsiddons
    Joined: Mar 6, 2006
    Posts: 1,481

    dsiddons
    Member
    from Indiana

    I was going to buy a entire kit but for some reason I found some negative info on them. Good to hear so much positive feedback with the aftermarket assembles. It's a huge bitch anymore to make this old original shit work well.


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  20. GOSFAST
    Joined: Jul 4, 2006
    Posts: 254

    GOSFAST
    Member

    I'll add this also, we stock a Ross piston/metric ring pack for a 3.228" finished bore x 4.000" stroke also. I only have these in this specific bore size due to the metric ring availability.

    What we recommend for a really good performer would be the block-plate finish hone (mandatory here), the metric/moly ring pack, coated cam brgs, this tightens up the cam to brg clearance slightly to help with higher oil pressure, an M-19 Melling oil pump, and a set of bronzed-lined guides (machined for Viton stem seals, photo below) along with some stainless valves. They do not have to "racing" valves, just stainless. Staying with the 1.500" valves is fine for most builds.

    I would NOT build any Flattie without the block-plate-honing in the program, period! The head-pinning would be a customer choice, not mandatory. I also would machine the casting ahead of time for the 95% oil-mod, whether it's to be functional or not! It's easy to do in the Bridgeport with the empty block.

    The most popular combo we sell is the 3.312" x the 4.250", I do NOT recommend the 3.375" bores going in, too much risk involved for the end result. Personally I like to leave as much of the original bores in place as possible. Bore it enough to start with "clean/straight" holes.

    (Add) Eagle now has the conventional style 4.000" stroke cranks with the journals for the OEM conn rods. Have used both lines, Eagle and Scat, still prefer the Eagle cranks. Like I said earlier however I do prefer the Scat rods, lighter and easier to work around. By the time you find a good used shaft, mag it, cut it (to whatever size), and make it usable I think you are better served with a new piece. You end up with std/std bearings? Just my take on it.

    Thanks, Gary in N.Y.

    P.S. Here's a sort of "rule-of-thumb" info with respect to cam choices/stroke. Generally speaking, a "lighter" ride would get more duration on the cam, need less stroke, a heavier one less duration on the cam, but a longer stroke. This was one reason with the heavier Merc's the longer stroke was eventually chosen. It needed slightly more power than the 3.750".
     

    Attached Files:

    Last edited: Mar 7, 2014
  21. chinarus
    Joined: Nov 9, 2010
    Posts: 499

    chinarus
    Member
    from Georgia

    gosfast,

    RE "Ans. The pinning job sounds real easy but it's highly involved. It is done with a fixture incorporated into the block plate we use for honing."

    Curious - How much do the cylinder walls distort when the block plate is torqued?
    Had one made for some 4 cylinder race motors I used to build but
    First time I have heard of a flathead engine builder using one.
     
  22. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member


    Great information. I will be getting in touch with you
     
  23. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member

    Well I built my engine early spring and have put quite a few miles on it since so I thought I would post a review for others to help in their decision making.

    I bought a 4 1/4 x 3 5/16 scat kit from H&H flathead. The price was good and the customer service was excellent. The rotating scat assembly came with rod, main and cam bearings (king bearing.) I had a valve kit from reds headers and a 400jr from delta. I did the 95% oil mod. Pineapple here on the hamb did the valve job for me. I ported the block myself and polished the outside of the block. Parr machine in hot sulphur springs colorado did all the machine work and I had him check the balance if the rotating assembly. It needed very little work to make it right by his standards. Uncle max rebuilt two 97 carbs for me that are flawless to top the package.

    Now the performance review. The engine is powerful. I am very happy with the setup. I love right at 8000 feet in elevation and take this car to 10k ft traveling out of the county and I have no problem climbing the mountain passes. I drove the car to the kkoa lead sled show in July and I am not sure what the elevation is in salina but DAMN the car had some nuts.

    It was running warm when I put it back together with the factory radiator. I had it recored with a five row rad. It still ran warm. I finally installed stats and that cured the problem. I believe in having stats now.

    All in all it is a great combo and makes great power for a flat mill. I would recommend the same set up to anyone.
     
  24. dan c
    Joined: Jan 30, 2012
    Posts: 2,222

    dan c
    ALLIANCE MEMBER

    my 2 cents--if you already have that 400jr, go for it. your car isn't a lightweight and i think you'd be happier with something less "racy."
     
  25. gotit
    Joined: Aug 27, 2009
    Posts: 357

    gotit
    Member

    It's all together and running. I have probably close to 3000 miles on it and I think the cam is fantastic. I had the cam in the old 239 and it was street able but had a ton of lope. Now with the 296 it has very little lope and makes a ton of power. It works very well where I love because everywhere I go I have to climb big hills above 9000 ft in elevation. I couldn't be happier with the cam.
     
  26. HotRodMicky
    Joined: Oct 14, 2001
    Posts: 1,771

    HotRodMicky
    Member

    The 400jr is not as radical as many think
    Just a good cam for a street motor
     

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