yes, even with the vacuum unhooked it still pings, BUT, i believe i have figured this out. The builder i bought the distributor from built it to my specs but something happened between him shipping it to me and me installing it because when i watched it with my timing light, it was advancing into the 50's WITHOUT the vacuum hooked up and into the 60's with the vacuum hooked up! Im actually surprised it didnt ping even more! Its a shame because it liked all that advance as far as performance besides the pinging.. So anyways, he had me send it back to him to put it back on his distributor machine and see wth happened..

You have a MSD ignition box? Have seen some that were wonky and added lots of advance on their own.

Into the 50"s/ 60's without vacuum advance yeah I'd say some thing is wrong. Unless your starting with 30-40 degrees. Let us know what he finds.

ok, the spark plug is an NGK XR4. I didnt think that was the actual number but looking it up, it actually is, just XR4..also lists as 5858. I cant find a chart that shows what the next colder NGK plugs are.. Also, what other things will happen with going with a colder plug? it wont run too rich will it?

Like the others have pointed out, that TOTAL MECHANICAL advance is WAY too big!!!

I'm a small-block guy, and with 21 initial I aim for about 35 deg. TOTAL mechanical. The VAC can is configured to toss another 15 in at cruise, and since at WOT it gets no vacum signal that keeps it safely out of contributing any advance.

Take the distributor apart and see what's going on with the advance mechanism.

It could be one of two types:
1) Old Mopar OEM thing
2) More recent (and Aftermarket only???) version which allows a much easler adjustability to BOTH the TOTAL advance as well as the actual CURVE

Here is what that distributor looks like:

That's a hot plug. It will add to your detonation problem.

The last digit specifies where the plug is in its heat range. XR4 is a plug that cross references to a JY12 to JY14. This plug would be on the hot side for a 7.5:1 motor with a 2.76 gear in a 5000 lb Imperial that almost never sees more that 2000 rpm.

I would not put anything hotter than a -6, like a NGK r5670-6, and would consider a -7.

And I also agree with what folks are saying about your full advance timing (>50°) being too high, and possibly being too lean. Plugs is the easy first step.

A few questions..if i go to a 7 heat range, it wont start sooting up the plugs? It already stinks like hell at idle, but looking at the plugs, they look good. like correct mixture..Also, Looking at the NGK R5670-7, they are 7.00 each compared to the 3.00 each of the XR4, can you tell me of a cheaper alternative with the same heat range as the R5670-7 being this is experimental, dont want to spend that much if i dont have too..

crossing the R5670-7 that you recommended crosses to the champion J12Y, which you said also crosses to the XR4 i already have..? confusing

If you are running a hot plug it will look cleaner with a rich mixture than a colder plug will. IOW, your hotter plug might be crutching your rich mixture. An O2 sensor will be if use sorting that out.

so do i need to go 1 or 2 steps colder on the plugs? Would 1 step be enough to help with the pinging?

anyone? 1 or 2 steps colder?

I would go with the -7. Still shows as a middle of the road plug, not necessarily a cold one. Is the timing still going to 50-60 reved up with no vacuum advance?

Havent had a chance to get the distributor back in yet, so hopefully tis weekend i can check it out.

I would get the timing issues fixed before I worry about plugs. With the timing right you could be fine.