Installing Distributor & Finding TDC

[Rick D]

Hello all.

Want to confirm I am doing this right… just installed both heads and the intake manifold on my 1997 merc 5.7L and need to now install the distributor from fresh since the crankshaft was turned with it out.

So to install the distributor, I need to find TDC on cylinder 1 by removing plug 1 and when I feel compression build, stick a long straw in the cylinder hole to determine when the piston is at the top of its stroke. Once there, find the line on my harmonic balancer and align it to the 0 degree mark on my timing chain cover. This is TDC, correct?

Now, I did scribe a mark prior to pulling the distributor so I have a rough sense of where the housing should be. Bottom line is when I match up the scribed marks, I need to make sure my distributor shaft is pointing at the number 1 wire contact the the cap, correct?

Just want to confirm before I attempt on Tuesday.

Anything to be really careful to avoid doing here?

Thanks,

--Rick

 

[BillV]

Not sure I would use the straw. I usually watch #1 intake valve close and then look at the line on my harmonic balancer and align it to the 0 degree mark on my timing chain cover. At that point you have already fired #1 so you need to install distributor indicating that. Rotate engine again until #1 intake valve close and then look at the line on my harmonic balancer to see if the distributor is about to fire #1. If done correctly you should be firing just before TDC, about 4-8 degrees BTDC depending on engine model. I pay very little attention to initial timing and only use total timing for my engines, usually about 28 degrees which ends up being 4 degrees BTDC.

 

[pdecat]

Just use your finger to find the compression stroke on #1, don’t worry about being precise, then line up the timing mark. Drop in the dist with the rotor pointing at the #1 position on the cap keeping in mind that the shaft will turn a bit when it finally seats. You probably will have to turn the oil pump drive to get it to drop all the way or just rotate the engine a bit or spin the starter and see if it drops.

Newbys usually get it one tooth off the first time.

 

[jtybt15]

Just so you don't get confused, Your procedure is as good as any.

As Bruce said, the drive gear being helical, the point will rotate down clockwise about 5* as it seats. The oil pump is driven by the dist shaft and the slot has to align with the bottom of the dist shaft so the pump slot has to be about 5* counterclockwise of the TDC mark you made. a long screwdriver will turn the oil pump to line it up.