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Liquid cooled Knuckle

  • July 17, 2013 9:59 PM PDT
    The attached are pictures I reciently took of liqiud cooled Knuckle engines put together by a friend of mine.   He has the original patterns and castings and etc.. They were used in full sized midgets before and after WWII.  "Drake" motors.  Then the 'baby' Offy was introduced and it put them to bed.  The first photo is one that will go into a machine that is being restored.  The 2nd shows one in an old midget that dates from the early 50s.  Edgar Elder built and raced it back then.  My friend owns it.  The last is one that he put in a rat.  Just Harley pieces off the shelves to make a runner.  Notice the L series S&S and the tubes that run through the right tank.  It's a radiator.  Fuel only in the left side.  There is another radiator device on board to ensure adequate cooling.  He started it up for me.  We also started up Edgar's old midget.  I had not heard that thing run since I was a kid.  Just thought some would like to see this old stuff.  There has been water cooled Harleys around for a long time. 
  • July 18, 2013 12:08 AM PDT
    I've never seen such...thanks for sharing!...are those freeze plugs in the cylinders?..... I've learned something new today, now my day is complete....must be Miller time...
    • 5417 posts
    July 18, 2013 3:04 AM PDT
    Never saw one either. Pretty cool but it just looks so strange without the fins.
    • Moderator
    • 14246 posts
    July 18, 2013 5:00 AM PDT
    Nice!
    • 846 posts
    July 18, 2013 5:34 AM PDT
    Never seen or heard of one, looks sharp, thanks
    • 2970 posts
    July 18, 2013 6:10 AM PDT
    Good post, thank you for sharing !!!
  • July 18, 2013 10:02 AM PDT
    ****** awesome post. Good to see that hasn't died off. Thanks!
  • July 18, 2013 2:22 PM PDT
    springertim wrote...
    I've never seen such...thanks for sharing!...are those freeze plugs in the cylinders?..... I've learned something new today, now my day is complete....must be Miller time...


    Sounds like you would like to know more.  Over the years I have mentioned "Shaker" motors to HD guys and got blamk stares...except for one or two old fossls like me.   We called them shaker motors because they would shake the midget right and left because of the positioning of the engine.  Back then Drake made better forged rods and pistons and the crank wheels were welded up and the crank pin moved out; that and a bore increase.  They ran alcohol.  The stock Linkert racing carbs had float bowls that were too small for a fuel motor so they cast-up bigger bowls.  Look at the super rare carbs on the red engine.  Also note the chromed bar that runs from knuckle to knuckle.  That is a compression release that actvates the exhaust valves when starting.  It was usually controlled by a cable to the cockpit.  They had a massive compression ratio and would otherwise skid the rear tires when the driver engaged the in-and-out box when being pushed to get the engine fired.  When i was a barefoot kid Edger woud pull the midget out of the shop before an event and then round up a few of us Okie kids playing in the street and tell us to push him off.  I remember that the best position on the rear nurf bars was near the center because the pipes woul blast out hot alcohol fumes when she fired.

    No the ports are for alternate water hoses.  I think it is possible to water cool a HD without out the butt ugly radiator hanging on the frame down tubes like the present artical HD is peddling.  I could not bring myself to ride one if there was a chance of someone I know seeing me even if the bike was free.   

  • July 19, 2013 8:35 AM PDT
    Thanks Salt, I appreciate the schoolin'...any idea what the cu inches was with those cylinders? the horsepower they put out?...that red engine is just a thing of beauty...with the brass and polished 'luminum.....
  • July 19, 2013 12:20 PM PDT
    springertim wrote...
    Thanks Salt, I appreciate the schoolin'...any idea what the cu inches was with those cylinders? the horsepower they put out?...that red engine is just a thing of beauty...with the brass and polished 'luminum.....

    Displacements changed by rule changes but figure 85 inches or so.  The wheels were welded up and re-machined to get added stroke and the bore was increased.  There were no 'after-market' big wheels available back then.  Remember that the first 74 inch OHV Knuckle was 1941.  Before that they were 1 liter [61 inch] motors.
     
    Horsepower?  As they were on alcohol it would be reasonable to assume one HP per cubic inch.  Bear in mind the horses were a lot bigger back then than the curent ponys that are currently counted.  [My manual for my stock 41 Knuck says 9 HP].  In anycase horsepower is a worthless way to judge competition motors [IMHO]. 

    In my 'old fossil' opinion the red motor is outragiously 'over-restored'.  Pimped up like a French Tart a Paris alley, it's a thing of beauty but they didn't look like that back then in the heat of battle.  Also, if closely looked at, it can be determined that the barrels and heads are different than the midget and bike engines.  It has cast iron pieces...an early version.  That is why they are painted.  The head and the 'outer' barrel, after machining and insertion of the valves, was brazed together!  The head did not un-bolt.  No problem, like all racing when an engine pops you generally lost everything anyway.  The aluminum head/barrel engines, of course, have a pressed-in 'wet sleeve'.  Added a pic of an engine being assembled.       

    • Moderator
    • 16441 posts
    July 19, 2013 10:27 PM PDT
    Freakin WOW!
    • 6 posts
    July 21, 2013 1:13 PM PDT
    Interesting, was unaware of any of this
    Had a vague awareness of what I think was referred to as "3/4 Midgets", more or less similar to todays Sprint Cars - Power plants were your choice:
    * Ford "60", flat head
    * Evinrude 2 stroke marine
    * Offenhauser, purpose built OHV (I think anyway)

    Only vague familiarity because back-in-the day I was trying to buy a Ford 60 from an old man and it was in a small, open wheel race car.

    Here is an odity at the Glen Curtis Museum in Hammondsport NY
    (If the "Odd Ball" motorcycle club puts on a show go to it. - They like their cycles straight out of the barn. Wash off the chicken dropings and show it.)


  • July 21, 2013 11:46 PM PDT
    This is some interesting stuff Salt..... I figured they were stroked just by the length of the barrels but I hadnt thought about no aftermarket wheel availability....they welded up the crank pin hole and drilled another further out on the wheels...cool.... and then tied the head to the cylinder...love hearing about this kinda thing.... There was a guy that used to run harley drag racing circuit years ago....Pete Hill...he ran a blown knuckle...the only guy that I know of that really had good luck with the blower set up....consisitently I mean..... I dont care where you were around the drag strip....when he fired that blown knuckle up...EVERYBODY knew it...it kinda sounded like an ear-splitting loud  industrial popcorn popper.....