Just put the oversize pistons 74mm fromTHR in today Waiting on the head to...


Just put the oversize pistons (74mm fromTHR) in today. Waiting on the head to be finished, with the oversized intake valves. Megacam working on the cams, going with the 120-04, and the rocker arms. My question is...Could I install the cams and rocker arms, and the torsion bars while the head is mounted, or would it be easier to install them and then mount the head?

%d comments
  • I installed my cams, valves, rocker arms, etc. before mounting the head. Nothing wrong with doing it that way; in fact, if you didn't mount at least the torsion bars and retainers before the head went back in I would have to think that either a. you wouldn't be able to get the valves back in or b. the valves would want to keep dropping out as you were mounting

  • At the suggestion of Paul De Doncker I ended up removing the valve pockets from the THR pistons in my build. Makes sense. Those very sharp edges have a couple of things going against them.

  • your ahead of me Bruce McGregor :-) i just wanted to post the same

  • I think you are well ahead of me Paul.

  • 74mm THR piston of my engine

  • John, Paul and Bruce are you guys using stock cylinder sleeves with these 74 mm pistons?

  • yes we do Ronny

  • I will do the same on my project this winter and for once it's good to know that someone has walked the same path before me.

  • BTW, removing those sharp edges sounds like a good idea.

  • air doesn't flow in corners

  • if you need to as that question you need to have someones help so yes install valves first .]install head while getting the cam chain into place put rockers arms . install cams with each lobe as far away from the foot of the rocker arms so as there is no pressure on them then install cam bosses then return crank to LT mark then spin cams to the timing marks .do not confuse the casting lines on he cam with the timing marks

  • are you just polishing the edges off?

  • no this needs a bit of grinding first :-)

  • Yes, the cylinders have been bored. As a second thought, I wish I had gotten the cylinders to resleeve from THR.