70 L46 Tdc

[Bill L.]

I replaced the timing chain, pulled the distributor and had it rebuilt now I am ready to put the distributor back in. My question is determining TDC.

I was told by a mechanic that if I put a piece of paper or tissue in #1 spark plug hole that when the motor is cranked around to TDC that it would blow the paper or tissue out. Well I did that and while it did not blow out the Newspaper piece I placed in the hole I did hear quite a bit of air escaping as the mark on the harmonic balancer came around to the timing tab.

Does this sound as though it is at TDC. I was going to manually spin the motor to 8 degrees advanced once at TDC.

Motor is in car with all plugs but #1 installed and the exhaust manifolds are not installed yet. Valve covers are in place too.


Thanks! Bill

[Michael G.]

Re: 70 L46 Tdc

Piece of paper uh....interesting. You could try this Bill. Remove the left valve cover. Using a break over bar and socket on the bolt holding your harmonic balancer in place, rotate the engine till you see the intake rocker on cylinder #1 open then close. As the timing mark (on harmonic balancer) comes up on 0....your at TDC firing stroke. It will easier to rotate assembly with spark plugs removed as well. . Your now ready to stab your distributor.

[Wade L.]

Re: 70 L46 Tdc

If you are at the "0" timing mark and the #3 intake valve is open, you are at TDC for #1 (otherwise you are at TDC for #6).