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Technical MOTOR, Flathead timing 1940

Discussion in 'The Hokey Ass Message Board' started by zgears, Jan 18, 2004.

  1. zgears
    Joined: Nov 29, 2003
    Posts: 1,524

    zgears
    Member

    im looking to get my 40' flathead running soon. i understand the basics of timing a "normal" motor, but this "divers helmet" throws me for a loop. can anyone give a step by step tutorial?
     
  2. zgears
    Joined: Nov 29, 2003
    Posts: 1,524

    zgears
    Member

  3. Tman
    Joined: Mar 2, 2001
    Posts: 29,861

    Tman
    Member

    Look at Fordbarn www.fordbarn.com

    good info on that site, thats where I looked when I had a prob. I know we have some flatty experts here as well.
     
  4. Petejoe
    Joined: Nov 27, 2002
    Posts: 6,939

    Petejoe
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  5. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    These were meant to be timed to 4 degrees crank on a special fixture or on a strobing machine. They are made so that if all parts are good they can be accurately timed off the engine. Ford published a way to time the '42-48 with a couple of rulers in place of the fixture, but never published such specs for the early pattern--if you can find some nut like me with a fixture and get it timed, you can then measure it with straightedges and keep dimemsion for future timing.
    If you can't find a fixture, there are several courses. Best is to establish proper timing marks on engine, which should be done by interference method since you might as well do it accurately. Is engine together or are heads off?
     
  6. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

  7. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Hokay, I found and dragged out the KRW fixture and a three bolt distributor. Tonight will try to get it timed and come up with an early version of the above '42-48 timeitwitharuler technique. Or just mail me the thing...
     
  8. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Had it out with the KRW fixture and a '34 distributor last night. Dead batteries in circuit tester,corroded points on only 3 bolt distributor I could find, cold, cat walking through everything, annoying session, so I will redo later and make sure my results are repeatable and correct. For now, here's what I have: First, read the straightedge timing procedure for '42-8 distributor linked above. We're going to do the same thing on the early distributor.
    Look at distributor from behind, with coil straight up. Coil must be on for final settings because its contact spring is strong enough to move the plate a bit. You now have two bolt holes on right side, one on left. If you have the '37-40 with extra hole to fit V860, look at only the three holes used on your 85HP. Mark a direction of rotation arrow on top of distrib to eliminate one thing you can do wrong. On distributor models with timing slot on left (driver side), down advances, on earlies with slot on right up advances. This is wrong on that site unless I'm nuts.
    Lay a straightedge across edge of drive tang on NARROW side of drive. Hook a simple battery powered test light across point circuit. Rotate--light will go OFF at each firing point as circuit breaks. Turnit in direction of normal rotation so that lower edge of straight edge, the edge that is against the tang, is approaching the top edge of the upper hole on right. At this point, narrow side of drive is up and slanted so right end of your straightedge is up and to right. As ruler approaches hole, light should go out when lower edge of straightedge is 1/16" from upper edge of hole. If wrong, adjust at slot by retarding then moving adjuster towards advance until light goes out. Go around again and recheck. All movement should be in direction of normal rotation, and if you back up go past where you're going and then come back in proper direction. There is your base timing, and your starting point for experimentation once engine runs. I'll recheck all and make sure this is accurate and repeatable.
    Note that once you have located this with straightege you can scribe a line to match across back of distributor as a good-enough reference in case you have to change points by the road in east nowhere during a thunderstorm.
     
  9. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Next tech: are your heads on or off? All engines should have an accurate TDC mark even if Henry didn't think so.
    First, add a pointer--try replacing a lower timing cover bolt with a stud with a sharpened end.
    If heads off, no problem. Put # 1 so it's coming up towards firing position, bolt a steel strap across cylinder, put a bolt through middle of strap as a stop. Bring up cylinder by hand until it stops against your device, mark pulley with crayon, swing engine around other way until it stops again and markit. TDC is exactly halfway between your marks, make a permanent mark with a chisel by your pointer. Do NOT eyeball TDC--on an engine with long rods and offsets, you can only get close, and it's easy to doitright.
    If heads ON, piston is not even in sight, so trickery is needed. You need a long object here--a plastic tie wrap, fairly large size with hefty buckle, is perfect. There's one waiting for you beneath your nearest telephone pole with service box. Draft an assistant to hold the tie wrap so its buckle is all the way across the cylinder against the far outer edge. Repeat rotation-stop sequence as above. Repeat the process a couple of times to be 100% sure your lackey heldit steady and you can get same TDC each time. Measure pulley diameter and do some arithmetic so you can measure off 5 degree steps or so for 25 or 30 degrees advanced so you can check anything you need to with engine running.
     
  10. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Dwell: Find your two dwell numbers, the dwell for each point and the dwell for both together, in degrees. Acquire a degree wheel, a good round one if possible, but the cheap and easy to find half circle plastic one from the dimestore will do fine.
    Affix this to back of distributor shaft. Quickanddirty way would be HD horseshoe magnet from precision tool rack at Sears screwed to wheel, place it carefully and be careful not to knock it out of place. Better way would be to get the cam extender adaptor from any Ford repro place, a part that is meant to be used to lengthen a 42-48 can for use in earlier engins. This actually fits onto the shaft and allows you to make a solid, workman like tool easily.
    Hook up your test light across points. Block off each set in turn with a piece of clean cardboard between contacts and set dwell of each to spec. Yank cardboard and check total of both together--if slightly off, adjust the right points. Leave the left ones, which make the final timing break, alone.
    Note that if you make a good solid degree wheel, you can come up with a way to drop a pin thrugh a hole in the wheel and on through a bolt hole to lock the setup at your preferred timing point--just like a KRW fixture.
     
  11. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Here's an old post on repairing the '42-8 type distributor which is mostly applicable to the early distributor:

    If in good shape, these have a good curve and the stock dual point (This is a Mallory design, by the way) setup is good through the power range of a street flathead.
    Take it apart and check front&rear bushings for slop. Check rubber ring on vacuum orifice on flange--if it's fried, replacements are available. Most important is the advance mechanism--many that have sat for a while won't even move. Separate cam from central shaft by removing snap rings, clean the rotating surface and grease lightly on pivot and where springs rest. Oil and free up the little bearings where weights act on plate, then wipe away all surplus lube. Reassemble and twist cam to see that advance works. Clean up vac brake, lube, install with only light drag on brake disc.
    Go to http://www.btc-bci.com/~billben/dist.htm and use this technique to get points just so. Note that gluing a dime store protractor to an old distrib rotor is a shortcut, and will also tell you a bit about the centrifugal advance. This is really a dwell, not a timing, fixture--more on that later. I have a real KRW fixture so I don't mess with this...
    It’s a good idea to blueprint fit of timing plate while you are rebuilding to make tuning easy on the car. Rotate the plate in its position with the big snap ring removed. It is probably stiff and notch so that it is difficult to make small timing changes smoothly. Lightly file areas on edge that are brightened by contact, reinstall, rotate, repeat until you have a smooooth fit.
    Next, go to http://www.vanpeltsales.com/FH_web/flathead_engines_distr-timing.htm
    and time the sucker to stock specs. You can now play with timing (stock is usually pretty close to right) using the little scale on the side of the distributor.

    More on the "timing" fixture in the website: If you make a good solid way of mounting your protractor to the distrib drive, carefully set the distributor in its firing position for #1 or whatever, and make up a pin that accurately locates a hole in the protractor to one of the distrib bolt holes, you now have a close equivalent of a KRW timing fixture. Or you could make up a one-piece version of the two rulers device so you can use it conveniently without needing all three hands. Either way, the distributor and any spares can now be timed off the engine and R&R'd as needed. Tuning changes are then controlled from the little degree scale on the side of the distributor.
    While you're at it, determine how many degrees each mark on that scale represents--that has fallen out of my head, and I believe the value differs a bit from what Ford says it is anyhow. Remember crank degrees and cam degrees differ by a factor of two, and ALWAYS know which you are doing.
    Use original or good repro mounting bolts, not normal hardware. Original bolts have a slightly oversized shank to locte distributor accurately.
     
  12. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    Dwell numbers: Early V8 distributors are all Mallory design dual point--vacuum brake retard type. The two points overlap in operation to give the coil more time to charge between firings.
    1932-1936 early style point distributors--these have the moving points connected by a long spring-contact and the stationary points thread through little blocks.
    Total dwell is 34 degrees closed; each point separately is 24, both are closed for 14, both open 11.
    Use degree wheel and circuit tester to measure the 24 and 34 as above--much superior to setting gap. Gap to get close for dwell adjust is 012-014.
    Late distributors: Rare 1936 "pillbox coil" and 1937-40, 1941 helmet type, 1942 and '46-8 flat type. Points are completely separate, stationary points are part of a plate rather like modern points.
    Total dwell 36 degrees closed circuit, 22.5 degrees each point, 9 degrees both closed, 9 degrees both open. Gap 014-016.
    On the '42 up distributors you can glue a protractor to a rotor as an easy to make gauge. If clear plastic, spray the backside flat white, then scribe/Sharpie the degree spans of interest so you don't go blind.
    Test light if you don't have one: Radio shack two AA battery box, lamp socket, and bulb. either wire from bat box to either terminal on socket, wire from other terminal on socket to small alligator clip, other wire fron bat box to another gator.
    On early distribs clamp to point spring through cap window, on '42 up to terminal where wire and condensor attach. Other clip to distributor case. Light will go on when point closed, off when both open. Engine would fire when light goes OFF with normal rotation. Play with the test light until you understand the basic function: The idea is that as long as EITHER point is close, coil charges, firing only happens when BOTH are open. Thus the staggered arrangement allows longer coil charging.
    Also, the light is a primitive way of trouble shooting--if bulb is very dim at some times, you likely have crud/corrosion/dirty or loose connection somewhere, possibly on point faces. The distributor I timed last night would not even light the test light until I cleaned the points, brand new ones that had sat in there unused since about 1972.
     
  13. Ryan
    Joined: Jan 2, 1995
    Posts: 15,078

    Ryan
    ADMINISTRATOR
    from Austin, TX
    Staff Member

    great posts.... I thought I would bring this one back to the top for the masses...
     
  14. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 19,517

    Bruce Lancaster
    Member

    This stuff is coming back soon as a massive crab repair/setting/traditional mods article. Unionville haunt has volunteered as the photojournalist. Distributors, fixtures, tools, parts all over basement ready to trot. We'll gettitalltogether soon.
     
  15. Petejoe
    Joined: Nov 27, 2002
    Posts: 6,939

    Petejoe
    Member

    Tech post Ryan? These important posts get lost in the shuffle.
     

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