Did I mark the harmonic balancer correctly?

[Rob79er]

I am building my engine currently and the book says to mark the balancer when #1 stops going up (heads are off) and then turn the crank the opposite direction until #1 piston stops going up- the halfway point is TDC. My new balancer's marker does not line up with 0 degrees for some reason so
I marked 2 places on the balancer using the same point of reference on the side (end) of the timing tab. I placed a line exactly halfway between these 2 marks- which should be TDC. Then I moved the new line (by turning the crank) in between the other 2 to the same point of reference on the side of the timing tab. Since the factory line on my balancer is not at the 0 degree point I marked another line at the 0 degree mark on the balancer. Is this line my correct TDC now?

 

[Jack]

wrong damper

Maybe?
As suggested elsewhere ... it's likely an incorrect late-model balancer is installed ... why not exchange that new balancer for one that's made for your year?
Then the factory mark & factory tab will line up.
JACK:gap

 

[Rob79er]

Maybe?
As suggested elsewhere ... it's likely an incorrect late-model balancer is installed ... why not exchange that new balancer for one that's made for your year?
Then the factory mark & factory tab will line up.
JACK:gap

I wish that I could. The balancer was balanced with the rest of everything and has weight removed from it now.....

 

[Jack]

I wish that I could. The balancer was balanced with the rest of everything and has weight removed from it now.....

That's too bad ... even worse, the machinist did you a disservice by modifying damper ... it is correct to remove or add weight from crank ... not damper ... even when damper is included w/ assembly. If/when that damper goes bad ... oh well. Is this a "cheater" 383/400 ... hiding the stroke by using a 350 damper so as not to show the more obvious 400 damper?

If the #1 piston is at tdc ... and your new mark lines up w/ zero tab ... you're OK.

 

[GerryLP]

I am building my engine currently and the book says to mark the balancer when #1 stops going up (heads are off) and then turn the crank the opposite direction until #1 piston stops going up- the halfway point is TDC. My new balancer's marker does not line up with 0 degrees for some reason so
I marked 2 places on the balancer using the same point of reference on the side (end) of the timing tab. I placed a line exactly halfway between these 2 marks- which should be TDC. Then I moved the new line (by turning the crank) in between the other 2 to the same point of reference on the side of the timing tab. Since the factory line on my balancer is not at the 0 degree point I marked another line at the 0 degree mark on the balancer. Is this line my correct TDC now?

79er,

The problem is that discerning when the piston stops going up or begins to move can be tricky. I have turned as many as 4 degrees in my engine where it seems that the piston is doing nothing (up or down). Since your heads are off, bolt a mechanical stop so that it will stop the piston just before the piston reaches the deck hight. Then turn the crank the other way until it contacts the mechanical stop in the other direction. If you have a timing tape on the dampener, then this could be sufficient to read-off the difference in degrees (between the closest start and end points in degrees), divide by two, and turn the crank to that point.

Is your engine an externally balanced engine? I know that mostly 400 CI and 454's are externally balanced, and this situation is critical; however, an internally balanced engine should not be out-of-whack if the dampener is replaced.

GerryLP:cool

 

[Rob79er]

Well, the heads are now on so I won't be able to watch the piston ...This is just a regular 350 SBC.

 

[JohnZ]

Having a solid mechanical stop is essential for finding true TDC. Having the heads on isn't an issue - just get a piston stop tool at any speed shop (ten bucks or so, or make one from an old spark plug) and do the same drill; rotate one way to stop, mark balancer, rotate the other way to stop and mark, and your true TDC is exactly between the two marks.

 

[Rob79er]

Sounds good- how would you make one from an old spark plug?

 

[JohnZ]

Bust out the center electrode and porcelain insulator, tap the I.D. of the steel shell, and use a bolt as the adjustable probe (don't recall the thread size - I have a regular tool).