Finding TDC hopefully I did this right!

Hopefully I did this right. I put a piston stop in the #1 hole. Rotated the motor till it started to roll by the stop turned the screw in a little more and then it stopped. Marked the balancer and rotated it the opposite way and marked the balancer and divided the 2 it was like between 9-10 degrees so I split it in half. Is this correct? Being the balancer had no timing marks only way I could figure to do it. Also do you locktite the pulley bolts on the crank hub?

Thanks!

sean

 

always use a dial ind. seems the piston will have some dead space at tdc. and a loc tite is fine

 

we red loctite the crank hub also but this is a fuel motor

 

Sean, that is the way I do it also except I like to have the piston stopped down lower in the hole, about 30-40 degrees on the crank. (it is a little more accurate)

I also make sure there is no slop in the piston and I loctite also.

 

tdc

So being 30-40 on the crank how does that affect the timing of the motor? So if I set my timing at 28 degrees based off the way I did would it not be real accurate? Dont wanna blow my @#%! up!!!!!

Thanks guys!

sean

 

It does not matter specifically how many degrees you use to stop the motor. The reason you want to use 30-40 degrees is because since you will have some slop in the system of the piston stop ( rod clearence, Pin clearence, piston clearence ) etc by stopping the piston somewhere other than right at the top of its travel you will minimize the error caused by the slop.

I hope this helps to explain it.

Richard Gavle

foot note at say 2 degrees from top dead center a degree of crank rotation might cause say .02" piston movement at 30 degrees from top dead center it probably causes .1" although I am no math major so my numbers may be way off you get the idea I hope

 

Thanks Bottlefed, yes that's what I meant.

 

I use a torque wrench So if the stop is off center of the wrist pin you can accurately take in to account piston to wall clearance, as well as rod bearing clearance. I set it on 25# Hell I hope I am doing it correctly ??.

 

tdc

I triple checked myself and came up the same 3 times in a row. I could feel it move past the stop and rotated the motor back and did a 1/4 turn on the stop and it stopped the piston. I think I am close. Appreciate all your help very much!

Sean