I have recently swapped my original 383 RR distributor for a new MP distributor. My old distributor was set at 14 base and 38 total. I wanted and adjustable mechanical so I could give the motor more base. After installing the new MP I set the base at 20 and found my total at 37 all in at 3000rpm. I then set the base at 22 and now my total is at 41. The car runs good with now pinging on 94 octane. I cannot understand how MP states to have total at no more than 38. I am starting to think my timing light is bad, or my timing tdc is out. I am also looking for total all in by 2500rpm. I need some help before I go on a wild goose chase. It is a new rebuilt to factory specs with a mild cam. Thanks

You need to shorten the advance slots to match your set up.

On the mp dist there is a torx headed set screw that locks the adjuster on the slots. You can reach through the plate, and loosen it, then shorten the slots, and lock it down again.

To make it come in quicker, you need to put lighter springs in it.

IMHO when you start wiht a high initial (which is a good thing) you don;t need to bring it in quite as fast. I would try shortening the slot for the max you want, then see how it performs before you mess with the springs

You for sure don't want it to be pinging. I would put the initial back to 20 & with 37 total you are very close to ideal then you could add your vac adv back in & tailor it.

dave571, what do you recommend for total? I will try adjusting the slots. When I loosen the torx screws both slots move equally correct. I forgot to add something in my post. Why does the timing mark on the balancer move up and down very quickly when above 3500rpm? Under 3500rpm the mark is steady. I am using a snap on with dial adjust. I was looking at the equus with dial advance or digital. Should I spent the extra cash and go with the digital with rpm display. My wife is getting tired of setting the rpm in the car. Thanks for your help

RapidRobert, That is what I cannot understand. With my old distributor a tried the total at 40 and in pinged very slightly. Using this distributor set at 41 there is no ping. Thats why Iam thinking I have a problem with the light being out.

the spring tension & or the amt of mechanical adv(slot length) would be different between the two. If 20 gave you 37(& no ping ) I would bump the initial up a degree & if the total is 38( which is a good baseline for a BB) & stay there & play with some lighter springs if you wanted the curve in quicker. EDIT your snap on(w dial back) light is good. the fluctuating marks at higher rpm is either the tchain and or needs one of these on the end of the dist shaft to keep the dist tang from moving back & forth in the slot in the top of the intermediate shaft. check how much play yours has by grabbing the rotor & moving the shaft back & forth, not enough to move the weights out against the springs but enough to see how much slop there is where the tang sets onto the slot.

I usually shoot for 35 or 36 total.

Initial is what gives you nice crisp off idle response.


The slots will move equally, but usually what happens is they pop wide open intially. Then you have to mess around with them to get the value you want.

Probably the reason the MP pinged at slightly less total is because the MP probably advanced quicker (weaker springs) than the Mopar.

In theory, distros are pretty simple. If you imagine there is NO mechanical OR vacuum, the base timing is what you set.

The mechanical varies with engine speed, the strenth of the springs, to set the RATE of advance, and the slots that limit the travel sets how FAR (degrees) the advance.

Same deal with vacuum. Some are adjustable. How far they move is the amount (degrees) and whatever internal springs--and whatever vacuum is available at the carb--determines how "fast."

So if you put in lighter springs, and the advance comes in "too much too soon" you might ping at less total.

One suggestion I ALWAYS make is to degree the damper using a "positive stop" so you KNOW where the marks are. This also avoids the need for a delay timing light---I've seen a few that were not accurate, or became inaccurate after being banged around somewhat.

Guys, I just remembered something. When I pulled the original distributor and installed the new mp the rotor was not pointing the correct way as compared to the old distributor. Originally at tdc the slot in the distributor gear was parallel to the cam. I turned the gear to get the rotor to point at number 1. Is this okay? I would also like to check my tdc on balancer I made a piston stop, using a brass bolt. Should I grind the threads of the bolt end,and make it smooth? I am afraid of damaging the piston.

Thanks everyone for your help. I adjusted the mechanical advance on the mp distributor. Worked great. Now I am getting 22 base and 38 total. With Vac advance 55. Runs great