Re: Top Dead Center
Ok guys. I am in the process of rebuilding my merc 4.3 v 6 and want to make sure I am at Top Dead center so that the timing is on. When I dissembled I took here apart without getting tdc because I could not move it by hand. I then took the distributor out to get down to the heads. I did mark the rotor on the cap and the cap on the block. When dissembled I did not turn the engine. ( no more then to see if it was frozen, made sure lifters were all the same with the cylinder pattern). Now I want to find tdc and see it everything lines up. Please help. I know enough to take plugs and feel for #1 piston to be up but does it matter where the lifters are?
I'm assuming you are trying to find TDC to drop the distributor in, correct?
If so, the marks that you put on the cap for the rotor are going to mean squat unless there is the really odd chance the engine was at compression TDC on cylinder 1 when you pulled the distributor.
Personally I would start from scratch (ignore the marks you made on the distributor).
If you still have the valve cover off, it will be real easy to find TDC, just rotate the engine till cylinder 1 intake valve open and close then line up the marks on the balancer and timing pointer to 0. Drop the distributor in (may need to use a long flat head screw driver to rotate the oil pump drive to allow the distributor to drop in fully), with the rotor pointing towards cylinder 1. Take your cap, and figure out what the closest lug on the cap would be to the rotor when the cap is placed on the distributor. That will be the cylinder 1 lug. Install the rest of the wires on the cap going clock-wise while following the firing order.
If the valve cover is already on, you will need to place your finger in the spark plug hole, and rotate the engine until you feel a large burst of air come out of the hole. At that point, you are most likely on the compression TDC, so you will line up the balancer and timing pointer to the 0 mark, then follow the rest in the previous paragraph for dropping in your distributor.
BTW, what failed in the engine that caused the need for a rebuild?
Good Luck!
