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Technical Questions about a hot rod flathead

Discussion in 'Traditional Hot Rods' started by Norris McCarty, Oct 13, 2020.

  1. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    I have a 40 Coupe that has a 53 Merc bored 30 over with a Isky Max1, Joe Hunt distributor, Reds Headers, Navarro Heads and Navarro 3x2 with 97s. Trans is a new Tremec. The engine has 1976 miles and was built by a reputable builder in Austin.
    Here’s the you flathead gurus think this engine would be a better driver with a Holley or Edelbrock 4 bbl. and a Mallory Unilite?
    It runs ok, but I’ve spent a lot of time setting up the carbs(progressive linkage) and timing and I’m just not satisfied with the performance. It idles ok after syncing and setting mixtures on the carbs. I’ve set the timing using a vacuum gauge because there aren’t any degree marks on the Fluidampr crank pulley.
    Today I drove the car about 12 miles at 70 mph and on the way back I heard some detonation when accelerating.......came home and backed off of the timing a bit(using the vacuum gauge). I then had to reset the mixtures again because it was idling rough. I still haven’t been able to get the idle back as smooth as it was before I lowered the timing.
    All of this to question the 3x2 setup with the Joe Hunt distributor......while it looks really cool, I’m much more into decent performance and drivability. It seems like every time I turn around I’m adjusting the carbs and timing!
    What do you think? Would a 4bbl and more conventional distributor be a better setup for a driver? Surely some of you guys have experience with a flathead setup similar to mine.
  2. fabricator john
    Joined: Mar 18, 2010
    Posts: 95

    fabricator john
    from venice fl.

    is that a locked out magneto or does it have a advance ?
    fabricator john
    miss you dad
    stillrunners likes this.
  3. You've already been told about those fake mags.;)

    (Not sayin for certain that's the problem but...)
    stillrunners, Tim and VANDENPLAS like this.
  4. studebaker46
    Joined: Nov 14, 2007
    Posts: 661


    I am not a fan of flatheads but that is definitely a beautiful engine bay. Tom

  5. Beautiful engine, they look pretty but I'm not a fan of those mags. True, Flatheads don't make a lot of power but they should run good. I'm not sure what you are feeling or what your expectations are but don't mess with the carbs too much. Most fuel problems are electrical.
  6. 97
    Joined: May 18, 2005
    Posts: 1,628


    Maybe sticking my neck out, without more info, but I am thinking it's not the initial advance, but the total advance and the curve that are probably a big part of the issue, flatheads don't need or like the kind of total advance a SBC needs. Depending on the trans and the gear ratio , I suspect the engine is probably lugging a bit in a relatively heavy car with a lot of carburetion and a a lot of cam. IMHO that motor is more suited to a light roadster than a 40 coupe, and those distributors are more suited to a SBC than a flathead. I don't think a 4bbl of any kind will make much of a difference. In fact I would say maybe take the center carb out of the equation , leave it there, but disable it with a blanking plate, set the initial/idle advance with the vacuum gauge, and minimise the total advance to max out in the mid 20s, see how it goes, you may well just need to use that 5 speed a bit more too if the rear end gear ratio is quite high.
    Oh and those little air cleaners ( restricters) screw up the mixture too. Take them off altogether and see the difference, then you will need to find something that will pass a whole lot more air as well as keep the dirt out.
    Lil'Alb, acme30, Kiwi 4d and 3 others like this.
    Joined: Dec 14, 2009
    Posts: 2,849


    Lots of guys run 97’s once dialed in with little or no issues.

    your engine looks killer !!

    I would try better air filters as a lot of these little filters cause issues with restrictioning air flow.

    my first thought is the fake mag, as I’ve seen a lot of threads about there lack of reliability.
    Fact your constantly diddling the timing is my first hunch .
    Tim likes this.
  8. v8flat44
    Joined: Nov 13, 2017
    Posts: 606


    You can solve any engine problem by just giving me that awesome ride........i know........
    I'm thinking ign. or too restrictive filter ellements too. Single deuce on mine ran awful with paper filter; put the screened one back in...ran fine.
    VANDENPLAS likes this.
  9. Great point, those puny filters are diabolically bad.
    A million threads here about how shit they are and how they screw up tuning and engine performance. They are nothing but a massive choke.
    ted kovacs and Tim like this.
  10. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    Thanks for all of the advice!
    I think I’ll go ahead and order a Mallory Unilite today. I’ve run one before on a small block Ford and had no problems. I threatened to order one a couple of weeks ago.....then thought the Joe Hunt might be fine with the correct plug wires....but I guess I was wrong!
    Any suggestions on type of air filters? It had the standard paper filters on it and I bought the gauze type filters from Speedway. They are better, but I know still not very good.
    I’ve owned flatheads before but they we’re totally stock. I just want an easy starting, good running engine that’ll stay in tune. I’m not after a lot of power.......those days are long gone for me
    The rear axle is geared 3.80 and feels good with the T5 for the way I use it, which is to and from the office and an occasional 70mph highway run.
    VANDENPLAS likes this.
  11. Automotive Stud
    Joined: Sep 26, 2004
    Posts: 4,145

    Automotive Stud

    I disagree that the motor is too hot for that car, the max one cam is pretty mild. I agree it may be over carbed. I think it would probably run better with two-two barrel carbs rather than three.

    Try running with no air cleaners to see if that makes a difference before going any further with that.

    I don't know much about those magnetos, but trying the unilite sounds like a decent idea.
    mctim64 and VANDENPLAS like this.
  12. Jimmy Petrarca
    Joined: Oct 7, 2020
    Posts: 9

    Jimmy Petrarca

    Hi. Is that a four barrel intake on there? Or a true three carb manifold? If it.s a four barrel, Your choking the engine a higher RPM.s
  13. alchemy
    Joined: Sep 27, 2002
    Posts: 16,051


    When Mallory first came out with their distributors for flatheads they were curved for a SBC. Make sure the one you buy isn’t the same.
  14. saltflats
    Joined: Aug 14, 2007
    Posts: 10,375

    from Missouri

    Can't you still get a point's distributor for one of those? :)
    What ever you get, have it curved for your engine. ;)
  15. their is nothing better looking than a flattey with a 3carb set up but nothing runs better than a edelbrock 4 bbl. and as far as fake mags they are troublesome installed 3 of them and sent them back for repair they also look great for a static display, 97s are very temperamental if they shake a little they run lousy.
  16. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    I'll check on the advance curves on the Unilites. I think the flathead model only comes one way.
    I really think the 4BBL is the way to go, but I believe I'll do the distributor first, then the manifold/carb change.
    I obviously think the 3 2s look awesome, but they are difficult to adjust(extremely close together) and don't seem to want to stay adjusted. A slight change in timing seems to throw them off more than you'd think.
    I may even try blocking off the center carb, but then I've got to figure out a different linkage also. Because I'm running a progressive linkage now, I've only been running off of the center carb 99% of the time anyway, except at idle I guess? this correct? I'm really not understand how the secondary carbs come into play except for at almost full throttle when the linkage kicks the secondary(end carbs) into play.
  17. 19Fordy
    Joined: May 17, 2003
    Posts: 6,962


    Norris: Check to make sure your spark plug wires will work ok with the Unilite.
    Also, buy the correct matching coil and ballast resister , if needed. Plus, buy the Mallory surge protector.
    Mallory replacement modules are very expensive, FYI.
    Departed likes this.
  18. tubman
    Joined: May 16, 2007
    Posts: 5,310


    I had a 276" Merc in a '36 coupe with a Max-1 cam (essentially the same setup you have) with a Holley 390 on an Offenhauser manifold. I never had the problems you mentioned with that setup. The problems with a 4 BBL on a flathead is that it just don't look right. At least your car has a hood, so that's not much of a problem. The Hunt "LookaLike" magnetos sure look cool, but like many others, I have never heard anything good about them. Alas, I have heard a lot of bad things about Unilites as well. The problem with all aftermarket electronic ignition systems is that they all can die immediately, on the spot, leaving you stranded. A points ignition will usually give you plenty of warning that it is going bad, so you can perform your maintenance when you want in the comfort of your own shop. It sure beats the hell out of changing modules on the side of the freeway in the rain.

    My choice for a good looking, reliable ignition system for a flathead? A flattop Mallory dual point (either an original flathead unit or a converted SBC distributor). Those are all I run. Like some others have said, just make sure any distributor that you run has the proper advance curve. Chevrolets need a lot more than a flathead.

    As others have also said, that sure is a good lookin' engine compartment.
    joel, mctim64, Desoto291Hemi and 2 others like this.
  19. Tim
    Joined: Mar 2, 2001
    Posts: 11,747

    from Raytown Mo

    Another vote for ditching that distributor and change the filters.

    the issue you find with the small filters is even with a free flowing element they are still a tiny surface/ filter area and will choke it down some.

    for trouble shooting you could just pull them and feel the difference.

    If it were me I’d find an oval filter that could filter all three carbs together. Seems the easiest way to get good filter area, options in height of filter, and still keep a snazzy looking Flathead.
  20. tubman
    Joined: May 16, 2007
    Posts: 5,310


    That's another advantage of a 4 BBL; the filter problem is more easily solved.
  21. lostone
    Joined: Oct 13, 2013
    Posts: 1,438

    from kansas

    I think the argument of multi carbs vs single 4bbl was settled long long ago. Especially street driven, the single 4bbl will always out perform multi carbs.

    Agree the multi carbs look killer but what fun is a car thats all looks and no fun to drive?

    I agree, distributor first then look at carbs...
  22. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    I have suppressor wires on the car had copper cores but was advised to use the suppressors with the current distributor.
    I'd really prefer to find a points style Mallory if I can. I could use one of my Winterburn CDIs with points....they are a really traditional style CDI. Awesome CDIs that I've used on my old Porsches.
    Any manifold and carb recommendations for the 4bbl setup if/when I decide to tackle that? I've heard that the linkage will need modification? Like maybe turning the carb around backwards so the linkage is on the passenger side? I'm thinking Edelbrock? Electric choke?
    mctim64 likes this.
  23. TCTND
    Joined: Dec 27, 2019
    Posts: 164


    I don't think it's really overcarbed. With progressive linkage you are only running on one two barrel most of the time. The center carb should be set up for perfect running before the linkage is even connected to the outer two. Without having my hands on it I'm inclined to agree that the advance curve is likely the culprit (though not necessarily) and whatever other shortcomings those replica mag/distributers might have, the curve can be altered to whatever you need. The lack of a vacuum advance is a shortcoming on the street however; you can set it up for max power but in cruise it will always have less than optimal advance which is bad for mileage and can increase running temperature.
  24. Kiwi 4d
    Joined: Sep 16, 2006
    Posts: 2,877

    Kiwi 4d

    I have used these air cleaners from Grace and co . They are available in powder coated black and natural or chrome . I actually modified mine and fitted a K&N air filter so they are slightly taller with new SS mesh as we live on an unsealed driveway. Period perfect and would suit your sanitary engine looks.
    We have 4.11 gears in our 32 with .76 5th gear , sure first is a little low but its not a problem at all , 5th gear is perfect on the highway.
    Do you think the heat riser in your manifold is working and when cold is the fuel properly atomised ?
    Last edited: Oct 14, 2020
    Halfdozen, Jet96, Departed and 7 others like this.
  25. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    KIWI....Those air cleaners are awesome!!!
    TCTND.....yes, that's how I setup each of my 3 linkage hooked up until final sync.
  26. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 6,991

    Bandit Billy

    Watching this and hoping you try replacing the Mike Hunt distributer with something better before tearing the 97's off the flatty. Less restrictive air cleaners would be a big help as well. Are those real Strombergs or the Chinese knockoffs?
  27. DDDenny
    Joined: Feb 6, 2015
    Posts: 14,004

    from oregon

    Paging Mike Hunt.:eek:
    Halfdozen, Jet96, Lil'Alb and 2 others like this.
  28. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 6,991

    Bandit Billy

    Cant get anything past you buddy! Glad you aren't part of the mod (erator) squad :cool:
    Tim and Desoto291Hemi like this.
  29. Norris McCarty
    Joined: Apr 19, 2007
    Posts: 309

    Norris McCarty

    Bandit....they are real Strombergs
    I do plan on changing the distributor first, in fact I ordered it and a coil this morning.
    We’ll see how the 97s react with the Mallory Unilite first.
    Tim likes this.
  30. Bandit Billy
    Joined: Sep 16, 2014
    Posts: 6,991

    Bandit Billy

    I run my flathead on a MSD distributor and MSD 6BTM timing box hidden under the dash. No detonation issues. 3 97's that run strong...very strong. No leaks, no pings, no smells, easy start. Progressive linkage. Are yours progressive?

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