340 Static Compression Numbers and Test Procedure

340inabbody said

Ok so here is an update. I thought I would start with the basics first and not make any assumptions with the set up. So I thought I would start with the distributor set up. What I found has confused me. There is a painted line on the harmonic balancer that I have been using and appears to correspond to TDC. However the harmonic balancer factory scribed mark line does not appear to line up with TDC? Are the HB keyed so that the factory scribed line/mark are always TDC? Why would the factory mark be off?

Click to expand...

The factory mark can be off. If it is...that is usually bad. It can mean the outer ring has slipped on the hub and the damper is junk.

But, if the mark is BEFORE the actual engraved line on the damper, that may have been used to set total timing.

To do the math on that, is diameter times Pi divided by 360. Take that number and multiply it by the number of degrees you want to mark. It will show you how many inches away from the OE line you need to be to get 35 degrees.

So.....(remembering I hate math)
7.25*3.14159=22.776527/360=0.0632681*35=2.2143835

All that means is that 2.215 inches around the damper (ahead of he factory marking) is 35 degrees BTDC.

You can do the same for any circle to find out how far around the circle is any degree you want to know.