Thread: 12 O'clock and 12 O'clock

Tweet

Originally Posted by Rdobbs1977

I appreciate that 34_40. I know in this picture, my TDC on timing plate and balancer should be in alignment. My question is in that picture, #6 would be on the compression stroke, right? If I were to rotate crank one more time so both dots are at 12, that would put #1 on compression so that when I drop distr in, it will be pointing at #1, correct? Thanks,

Correct. When you put the motor together and align the crank sprocket at noon and the cam sprocket at 6PM, the number 1 piston is at top dead center, but it is on the overlap, not ignition stroke. #6 will be at TDC also, because it is the companion cylinder to #1 and will be on the compression stroke and ready to fire. If you turn the crank one turn, 360 degrees, and put both sprockets at noon, #1 will be at TDC on compression and #6 will be at TDC on overlap. I've often wondered why the Chevy engineers did it that way. I do know that it is prone to error to try and align the cam sprocket at noon and the crank sprocket at noon. It's much simpler to align the cam at 6 and crank at noon and then turn the crank one turn to get the motor ready to drop the distributor in and begin with #1. Put the rotor at 5:30, run #1 and then run the rest of the wires clockwise around the cap.