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PARADOX
12-02-2009, 12:22 PM
I need to get No. 3 Cyl to TDC. and may be evn to BDC, to do a leak down.
I'm not sure if I can "bump" the motor to the right spot.
Any good way to do this?

Thx
P

Chris
12-02-2009, 12:38 PM
Pull the lower pulley and stick bolts in the balancer. Make sure you're a couple degrees one side or the other and brace from the proper direction. 175psi will spin that motor briskly and if you have a bar in there the wrong way...

I wouldn't use the balancer bolt no matter how convenient it looks.

MERPerformance
12-02-2009, 09:12 PM
This is the way I would do this. Take it to TDC, use a long breaker bar, hold the bar and just take your pressure to 80 PSI or if you can hold 100 psi just go that far with the pressure that will give you your leak down %.

YoungPerformance
12-03-2009, 02:33 AM
I will put the TDC mark at the top of the balancer (the 12 o'clock position). Then I will mark the balancer(if it isn't mark every 90* already) at the 3, 6, and 9 o'clock position with a Sharpie or piece of tape. Then just put the balancer at 90* BTDC (for cyl. #3) on your mark. You will be able to get it very close. Close enough so that it should not move. Good luck.
Eddie

Thunderstruck
12-03-2009, 10:44 PM
I will put the TDC mark at the top of the balancer (the 12 o'clock position). Then I will mark the balancer(if it isn't mark every 90* already) at the 3, 6, and 9 o'clock position with a Sharpie or piece of tape. Then just put the balancer at 90* BTDC (for cyl. #3) on your mark. You will be able to get it very close. Close enough so that it should not move. Good luck.
Eddie

Amen Eddie.

Hell I marked the crank pulley on both motors with a paint marker and have used the marks for years. Take a straight edge and hold it across the pulley with one end at 0 deg on the balancer. Move the other end until you have cut the pulley exactly in 1/2 and mark the other end. You have TDC at 1,6 and 4,7 with those two marks. Then rotate the straight edge 90 deg and mark the 8,5 and 3,2 spots.

With a remote starter switch hooked to the starter bump the button with your hand, don't try to hold the button just tap it to get to each mark. I follow the normal BBC firing order to do the leak down. If the motor rolls over a little, roll the motor back to the proper spot but fudge a little before or after your mark for that piston until the motor holds. Leave the plugs in the rest of the cylinders to help hold motor still against the air pressure.

Holding the crank with a wrench is tough and can hurt.