12.54 with key off
12.46 key on

it is a consistent 0.8 volts differential everytime I checked after cleaning it all

 

I think it's missing a blue clip. I also believe I pushed it in a little

 

1) The way the engine sounds, it’s trying to start (as opposed to just cranking).

2) In the second video you can see where the spark timing changes from seemingly random pulses to more consistent pulses - it’s at this point the engine sounds like it’s about to start. I can’t say for sure but I suspect this is due to the ECM still attempting to adjust spark timing. Even with the bypass circuit (tan/black wire) unplugged, the HEI module is only sending and receiving signals from the ECM, so it doesn’t seem unreasonable that some adjustment is still possible within a certain range.

3) Which leads me back to beating dead horses - timing (sorry, but again, I can’t recall everything we’ve discussed).

SOME balancers from this era had 2 grooves in them because the timing chain covers actually had an upper and lower mark so timing could be checked from underneath; BUT the lack of a lower mark on the cover didn’t necessarily mean that a given balancer didn’t have 2 grooves anyway.

So, are you sure there’s no 2nd groove on the balancer? If there is, are you using the right one? The correct mark for setting the distributor timing would be the one that’s on the left if you’re looking at the engine from the grill. To put it another way, assuming #1 is at TDC compression, the correct mark would be lined up with the top pointer at about the 1 o’clock position and the second mark would be at the 4 or 5 o’clock position.

If you’re not sure about the 2nd groove, clean the balancer with a wire brush - rust can fill in the 2nd groove, making it all but invisible if you’re not looking for it.

 

There is 2 grooves in balancer and the way I did it was remove #1 spark plug and watch piston reach tdc on compression with scope but I am going to double check that I didn't get mixed up and redo it.

 

I found a broken distributor center button really hope a new one will get it started

 

I'd suggest without the cap, crank the engine make sure the rotor is turning free. Old school even with a new cap, if you have a trouble light, put the cap under it to check for cracks in the cap.

 

You gotta love it when something this simple ends up being the cause…. I really hope that’s it!

I’m in agreement with kevinpk though - with the cap off, verify the rotor is turning at a consistent speed, just for verification. Just remember to either unplug or ground the coil first…

 

Yes me too I actually verified rotor speed like you suggested just before I found cap was broken. I mounted rotor wrong the other day so could be I broke it then but when I look at older video truck has same symptoms so really hope I found the last problem preventing it from starting.

 

Thanks for posting firing order awhile back gumby. When I google firing order for 1988 Chevrolet cheyenne k1500 4.3L i get so many conflicting results. Also does the #1 inside cap have a meaning?

 

It probably has a meaning to the manufacturer, but usually caps that mark the #1 tower for identification are marked on the top between the tower and coil hookup.

Edit - This is a cap marked for the #1 tower