I know how to find 1 TDC and 6 TDC but I need to be able to find TDC and BDC of each cylinder for a leak down test. Is there any easy way to do this?

 

Chevy firing order: 18436572

So... piston #1 would be up on 1, down on 4, up on 6, down on 7, and back up on 1. You can apply this to all other cylinders.

ex. piston #5 would be up on 5, down on 2, up on 8, down on 3, and back up on 5.

The compression stroke would start two cylinder fires prior to the cylinder you are working with.

 

Measure the circumference of the balancer and divide it into 4 equal areas, starting with the TDC mark.

 

Yup. Then bring #1 to TDC. As you rotate the engine clockwise, each consecutive mark will mean that the next piston in the firing order is at TDC. Obviously, the important thing here is that the piston TDC lines up with the timing mark's TDC.

So, if #1 is at TDC, (following the 18436572 firing order), the next progressive mark on the balancer would be TDC for #8.

 

Thanks for the help guys; I just want to make sure I understand this. If you divide the balancer up into 4 equal areas it would be a big + which is 4 lines. So the first full rotation 1843 fire then on the second rotation 6572 fire, am I right?

 

a piston stop works well.

 

Sure, a piston stop works if you don't trust your balancer mark, but it would be kind of tedious to use a piston stop on all 8 cylinders.

 

once you have one, you know where the other 8 are.

 

Can anyone confirm my previous post, I want to make sure I do it right.

 

A combination of these two basic idea will get you exactly right. Use a piston stop to find out exactly where #1 TDC is and then do the math.

A tip: When you do find where exactly #1 TDC is, mark the harmonic dampner at 12 O'clock, or 11, or wherever, and then mark the timing COVER. Just scribe a line all the way across the dampner, lay a straight edge on it and make your mark on the cover. It doesn't matter if this mark lines up with your timing tab, just so you can ALWAYS locate TDC from now on just from your crank position. If you want to go to the trouble, remove the pulley and scribe a line from the inside to the outside of the dampner and you'll know if you dampner ever slips.

Unless you align your timing tab when you're building the engine you're not really sure it's accurate anyway.

HTH

 

lol, speaking of that, guess what i did lastnight....... lol.

 

You are correct. The first full time around you will encounter 1843, the second time around will be the 6572.

Finding #1 TDC would be easiest with a piston stop.