amazza76

iTrader: (1)

I am trying to verify TDC on a BBC. I borrowed a friends piston stop but it is not like the ones I have seen in Jegs or the like. The ones I have seen have an outer sleeve that threads into the spark plug hole and then an interior threaded rod that can be adjusted for depth. The one that my friend gave me has the outer sleeve but instead of the inner threaded rod, has a round screw going through the sleave retained with 2 nuts. The head of the screw is towards the piston. My problem is that I can spin the motor over completely and it seems like the piston never hits the stop. Is it possible that the screw head is not deep enough in the cylinder to contact the piston?

redbandit98

iTrader: (13)

that has to be what is happening..if it were hitting it, it would stop..its just not making contact with the piston.

mgkbull

I usually remove all the sparkplugs so the engine spins freely, then stick a paper towel in the #1 spark plug hole. Slowly rotate the motor (clockwise!) and as soon as it pops out, you'll be pretty damn close to TDC.

69chevy

That's the way I usually do it. Or if you have a friend there with you, tell him to cover the hole with a finger. He'll know when the piston comes up.

amazza76

iTrader: (1)

I have it ball parked already, however I am trying to find TDC within a degree or so to get everything dialed in perfectly. Spin the motor counterclockwise, mark the balancer, spin it clockwise and mark the balancer again. Repeat to verify and the measure exactly between the marks and that is TDC.