Rember that vacuum adjustment only changes what HG it starts to add timing it DOES NOT limit the total vacuum timing.
If you have a hand vacuum pump put it on the vacuum can and start pulling a vacuum and see when the arm starts to move.
Then make a few turns and test with the pump again so you see what I am taking about.

Be careful not to back the adjustment out too far as it will fall out of the plate or whatever it screws into, dont ask how I know
You may want to screw it all the way in counting the number of turns, write this down, so you know where it was before making adjustments.
I did not think of doing this and have no clue where it was before I started turning it.

Make adjustment and go for a test drive to see what that did for you.
Dave ----

 

The adjustment screw was found to be 4.5 turns out from the stop before testing. I test drive at several settings between 1 & 3 turns out and still heard pinging. I really don't know where to go from here. I guess I shouldn't have desmogged the thing as i was getting pretty good mpg and now it's horrible

 

On that particular design, they state to count the number of turns from the take-off diaphragm and move the adjustment the same on the new diaphragm (refer to instr sheet),

In this case, did your take-off offer this adj feature?

Another possibility is the damper ring slipped and initial timing is not what you think it is. You would have to find #! cylinder TDC with a piston stop and verify the marks line up.

 

I also did not have much luck with the vacuum adjustment to stop pinging.
IIRC between the base timing and the added vacuum the total was way too much and why the pinging.
I think I added heavier springs and it helped as the advance did not come in as fast.
I really need to get back into the distributor and make more adjustments.
Dave ----

 

It may well be in he DIST itself. One would need a timing tape and dial-back light to try and diagnose/recurve (after verifying damper ring has not slipped).

If the engine has been de-smogged, the needed timing events would change. The easiest way out would be to put the DIST on an analyzer and check for free operation and advance curve. Either the speed shop guy would know a suitable curve or you would choose one from pre-EGR.

Might be a good idea to remove the DIST CAP and operate the diaphragm with a vacuum source to check for plates movement and return. I would not trust a rebuilt, I would get the OEM analyzed and repaired.

Make sure it has the correct vacuum signal, only ported not manifold or a mix.

It is also a good idea when describing a DURASAPRK problem to include the color of the ICM stress relief. It may not be BLUE and have different characteristics.

You know, I am surprised after all of these years a TECH SHEET has not been offered as how to go about performing this period de-smog correctly (and legally depending on state of registration).CIPHER HERE - https://web.archive.org/web/20210212...000/03/timing/

 

What is this speed shop and distributor machine you talk of
The only speed shop that was here when I moved in 10 years ago shut the doors over 6 years ago and when I stopped in was not a lot of help.
Other than when I was in high school (trade school) I have not seen distributor machine and dont know of any shops that would even have one now days because everything is computer controlled
Only us dinosaurs still run distributors, heck I have a 70's car with a dial point distributor in it for when we get hit with EMF
No the car runs great so why mess with it.

The biggest PITA is the springs & weights are down inside the distributor so you have to pull it from the motor and then take it apart.
I did that a lot when I was doing the springs and mapping the curve. I did not know what I know now about the distributor so next time I should be able to nail it on the second try

I know my damper is good as I checked it for zero, used a dial back light and mapped the curve of the weights with different springs and have it in notes and would dig them out when I get back into this pinging issue.
But running high octan has fixed it for now. I also dont drive the truck all that much now that I am retired so running the higher octan is not that big a deal now.
Thanks for the information it's always nice to go back over stuff
Dave ----

 

I was afraid of that, but chose to say out of the weeds. However Kultulz did and he is exactly right, they need to be reset for non-emissions use which takes us further into the weeds. I had the luxury to use an OLD distributor machine that a fellow hotrodder had in his garage (MOPAR guy, great guy, who would rather eat worms than drive a Ford apparently, lol). Huge machine for what it does.

 

Sorry about that "over the head" stuff but it all has to do with limiting the total timing advance and being there are 2 different ways not counting vacuum it is kind of hard not to get in over any ones head, even mine at times
I bet there are videos on Youtube that show how to plot a timing curve, where toy need to start before jumping into the distributor.
Then others on how to adjust the weights, springs and limit the amount they add.
And lastly the vacuum can adjustment.
I am sure when you see them 2 or more times it will get that light bulb to turn on what we are talking about
Dave ----