O'Donell heads are crap

Discussion in 'RC General & Getting Started' started by vgsrc, Jun 3, 2004.

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  1. vgsrc

    vgsrc New Member

    I bought an O'Donell head for my O.S. 15, put it on and had nothing but problems. The engine would not idle, but at full throttle it ran like a champ. I even used the recommended glow plug, a McCoy mc59 still same symptoms. I was also using fresh fuel. After thinking about it for awhile, I came to the conclusion that the compression was too much. The instructions said to use the head shim from the engine, I did that. I think they should have mentioned using two shims instead. The other thing that sucks is that the head does not have a slot cut into it for flow through. I have since put my stock O.S. head back on and low and behold, no problems. Maybe I will buy another shim and give it a try later. Does anyone know who makes a good aftermarket head for O.S. engines?
  2. Steve M

    Steve M Member

    Dumb question perhaps, but why did you want to change from the stock head?
  3. vgsrc

    vgsrc New Member

    My last experience was with an O.S. 12 and it ran kind of hot with the stock head. I have heard people dog O.S. for the stock head design, saying it made a great paper weight etc... So I thought I would try to run a little cooler with the aftermarket head. But I think I'm going to stick with the stock head, after all it was designed for the motor right?
  4. redheat

    redheat Member

    Best cooling method short of ice cubes is a well tuned motor and cut outs on the truck or car body. Ventalation is the key to a cooler running engine you could purchase the biggest finned heat sink in the world and it still wouldnt do the trick if you didnt have air flowing threw the body to your engine. Dont really understand how you came to the conclusion that you had to much compression, in most cases an engine with low compression or is out of tune well not idle and the hotter it gets the less power the motor well generate . Anyway bottom line is that that heat sink shouldnt really have that big of an effect on your engine.
  5. vgsrc

    vgsrc New Member

    my engine was tuned correctly with the stock head on, then without changing any of the settings I put the aftermarket head on, and the problems started from there. since then I have put the stock head back on, still have'nt changed needle settings, and the motor runs perfect. I was saying the compression is too much because it would stop the engine from idling right, but while driving at full throttle it ran fine. it is possible to have too much compression. but like I said, stock head is back on, and everything is good, runs great.
  6. redheat

    redheat Member

    Good to hear that your engine is working for you with the stock head. I was just wondering why the bottom end was giving you problems at idle.
  7. vgsrc

    vgsrc New Member

    the bottom end wasn't giving me any idling problems, but with the new head, I had the idle screw turned in enough that it should have had the rpm's up quite a bit. when the engine died at idle, I started messing with the bottom end to try and keep it idling, but I ended up running too lean on bottom. that's when I realized no amount of tuning was making a difference with that head. so I put the bottom end back to my starting point, put the stock head back on and voila!
    I was just disappointed in that head. a person would like to believe that anything is better than stock; not always true. if I get a second shim, then I will try to run the odonell head again. until then I am having fun with my car.:)
  8. redheat

    redheat Member

    Right on Ive had my moments with parts that are suppose to help performance and end up being more of a headache, motor saver filters being one , at any rate cool things are working out .
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