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  1. #1

    Default New Meat

    Hey folks,new guy here.
    I'm working on my first F head,1919 police. Probably be drivin' y'all crazy with questions and ideas.

    My current dilemma is finding 20 over pistons. Anybody ever thought of using Tecumseh pistons? The HH80,HH100 and OH140 have the same 3.12" bore. Been trying to get the info on pin dia and comp. height. I've owned two OH Tecumseh motors and I know from experience they are tough as nails.

    Next ?
    IF I do wind up using such a beasty would it be a good idea to omit the oil ring.

    Thanks, SW

  2. #2
    Join Date
    Sep 2005
    Sarasota, Florida


    I'm motor challenged, SW but I have owned a number of early Js. Cylinders, and top end work is a problem as there are unique issues with pocket valve motors, blind bore cylinders, and cast iron pistons. Apparently, many Cannonball riders have found solutions to those problems, but they seem very reluctant to share the knowledge. You should check out this 1919 build by our fellow AMCA member, John who very graciously shared his discoveries, and detective work on this thread:
    Eric Smith
    AMCA #886

  3. #3
    Join Date
    Nov 2008


    Talk to Dale at Motion Machine in Lynchburg VA. He shows a video doing a couple of JD cylinders in a CNC machine. Does both in under a minute. I think he does a lot for the Cannonball guys. You can Google them and it should come up.

    Tom (Rollo) Hardy
    AMCA #12766

  4. #4


    I'm capable of doing the work. I may have to farm out the initial bore because of the huge ridge at the top of one of the cyls. I have micrometer hones and lots of measuring devices to finish up with. It's allocation of parts that is the problem.

    There is a used piston assembly on fleabay. Reckon I'll have to buy it to get the measurements then throw it in the trash.

    Working on the generator today. Had to make the screw that retains the interrupter plate. 1/4-32 countersunk head is not something you're gonna get at Ace hardware.

    I love my ol' atlas lathe!!

  5. #5
    Join Date
    Jan 2006
    West Coast Florida


    I'm trying to follow along here
    You said "Had to make the screw that retains the interrupter plate. 1/4-32 countersunk head is not something you're gonna get at Ace hardware."
    I don't know what the interrupter plate is. Got a part number for it as well as the screw you mentioned? I'd like to be able to understaned which part your referring to.

  6. #6
    Join Date
    Dec 2015


    HI, welcome to the forum. Like eric said, I have built one of these from a starting point of zero knowledge on these early F's and J's. I am no expert although there are a few genuine experts on here, however if you have any questions that I can answer I will gladly chip in. Mine is a 20F so one year later although the differences (i think) are small.between '19 and '20.


  7. #7


    The centrifugal switch on the back of the 235 generator that disconnects it from the battery when the engine stops. The plate that holds the weights is mounted to the back end of the armature shaft with a countersunk screw. That screw is 1/4"-32 RH thread. A monkey with tools had cross threaded that screw sometime in the past and booggered it up so it wouldn't tighten the plate and the whole assembly was flopping around in there.

    The screw slot was pretty McF***ed also.

    I used a 1/4" grade 5 hex head bolt with a couple inches of unthreaded shank and threaded the shank to 32 tpi then cut the counter sink head and screwdriver slot.

    I've had to make a lot of parts for this old beater. Some of the parts could be bought but hell,what's the fun in that.

    I'm a clockmaker by trade these days and making parts for 100+ year old machines is an everyday thing.

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