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Tdc And Belts On A 620 2v

Discussion in 'Technical Help' started by cj haughey, Jul 20, 2019.

  1. I bought a project monster that someone had stripped down before i got it. Now I have sorted out all the electrical issues and rebuilt the engine. Now my problem is that I have very little compression as in 100psi.
    My question is the belt marks if lined up on the layshaft it leaves the horizontal piston off TDC. If I line up TDC on the vertical piston through the window on the side then the layshaft is out by 110 degrees instead of by 90 degrees. I am wondering are the belts as in cam markings done with the horizontal piston on TDC and does this mean my layshaft marks are wrong.
    Thanks in advance as cant wait to hear her run and start on the cosmetics.
     
  2. The belts are fitted with the engine at TDC on the horizontal cylinder. At that point the dot on the layshaft pulley should line up with the line on casing. If it doesn't then the layshaft is timed wrong on the other side at the back of the flywheel.
     
  3. Was thinking that Derek but looks to be aligned up right on the gears at the flywheel. But if it is meant to be done on TDC on horizontal then maybe I should make my own marks
     
  4. She is set up as per that diagram alright. Even with the vertical marks aligned the gap on the gear for the tdc sensor seems to line up
     
  5. I have never known the timing marks to be wrong. Remember also that the layshaft turns at 1/2 engine speed. With the engine at TDC start firing stroke on the horizontal, 270º of forward crank rotation will bring it to TDC at the start of the firing stroke of the vertical cylinder. The layshaft will have rotated through 135º.
     
  6. Am going to go back at her and ignore everything I have done so far and see if something jumps out at me
     
  7. Probably a good idea.
     
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