Adjusting a vac adv distributor?

[747mopar]

I'm about to pull my hair out, I've been fighting the timing on my Charger for far to long. I started out with a mechanical adv that worked well for a while then started breaking up when mashing it (hard acceleration). The timing was set at 16 btc initial (it actually liked allot more initial than that but was hard to start) and 36 btc all in at 2,400. Since I mostly cruise with it I decided to try a Mopar vac adv, I can't pull it below 20 btc without it dying now so with it at 20 it runs decent but still stumbles when downshifting and mashing it. Set the initial at 30 and it idles better, pulls better vac (16), has better throttle response, pulls flawlessly threw the whole rpm range but has a miss while cruising (2,100-2,500). I checked the timing mark while I was degreeing the cam so I know it's right and it was set with the vac disconnected. Is there a reason this thing wants so much timing? I haven't had anyone around to help me check the advance so until then I don't know what rpm it's pulling it in at. From what I've done it seams as if it's coming all in a little to early causing the cruising speed miss since it doesn't do it with the initial set at 20 and does at 30. My distributor (383-400) doesn't have the adjustable vac but I have 3 440 ones that do, are they (the vac pods)interchangeable? Never messed with a Mopar distributor so any help would be appreciated.

 

[Photon440]

If you had one of these adapter rings http://www.classicmoparforum.com/billet-mopar-rb-to-b-distributor-adapter/ you'd be able to use your 440 distributors in the 383/400.

 

[747mopar]

If you had one of these adapter rings http://www.classicmoparforum.com/billet-mopar-rb-to-b-distributor-adapter/ you'd be able to use your 440 distributors in the 383/400.

Thanks, I might have to make me one.

- - - Updated - - -

O.K. a little more testing today, I figured that maybe the vac adv was putting a little to much timing in and causing the miss while cruising so I decided to just unhook it and take it for a drive. Surprisingly this is the best the car has ever ran but what is more surprising is what I found when I got home and put a timing light on it, the timing is 36 btc. There is no advance with the vacuum unhooked and it runs, starts, accelerates and cruises great as a matter of fact this is the best it has ever ran. I know there will be doubters so I just might do a video of the timing and of it going down the road. I'm clueless as to why 36 btc works everywhere with no advance at all but one thing is for sure IT'S GOING TO THE DYNO BEFORE NEXT SUMMER!

 

[Photon440]

If you have no advance at all, then either the shaft has seized so the mechanical advance won't work, or your springs are disconnected meaning it's always full mechanical advance, or something's broken inside...

I had a Pontiac that was like that - seized up so the mechanical wouldn't work. So the only way for it to run was with 35 BTC dialed in. It was harder to start and idled rough, but otherwise was fine. An easy fix.

 

[747mopar]

Found out something very cool today, I was looking at my Mallory mech adv distributor when I noticed a plate where the vacuum pod would be that had an arm fastened to the plate inside (just like a vacuum adv). After seeing this I unscrewed the plate to see if my hunch was correct and what do ya know it's just a vacuum advance distributor with an arm holding the plate stationary making it a mechanical. This was a very pleasant surprise because now I only have to buy a pod to convert it and Mallory has already supplied the part #. Sweet, this Mopar distributor is not very friendly to adjustments so it will be nice to get it off of there.

 

[miller]

Suppose you already know...

Either, any distributor's advance mechanism, needs to be clean, and lubed, to work right. Easy to tell, by just twisting on the rotor.

Good to hear you have things working!

 

[benno440]

IMO please dismiss if you like but throw all these other POS in the bin and get a mechanical advance MSD dizzy never look back, my car is also a street car and I have never had any timing dramas. on the ball since I installed it.
feel free to tell me to f**k off as I have had a few too many scotches tonite, yes it is 11:00pm here now. haha

 

[747mopar]

IMO please dismiss if you like but throw all these other POS in the bin and get a mechanical advance MSD dizzy never look back, my car is also a street car and I have never had any timing dramas. on the ball since I installed it.
feel free to tell me to f**k off as I have had a few too many scotches tonite, yes it is 11:00pm here now. haha

LMAO, I'm still a little unsure of whether or not I'll run an advance at the moment because the one that's on it right now runs best with it unhooked. As for buying an MSD I don't think so simply because I have a brand new Mallory to work with that just needs re-curved.

- - - Updated - - -

Suppose you already know...

Either, any distributor's advance mechanism, needs to be clean, and lubed, to work right. Easy to tell, by just twisting on the rotor.

Good to hear you have things working!

Thanks, Yes I'm aware and I'll check into it but don't plan on using it now that I know I can use the Mallory. I need to pull the coil wire and check the timing while cranking because I suspect someone has put heavy weights and light springs in it to the point that it advances right off the bat. Reason for my suspicion is that it wouldn't even start with the Mallory mechanical on there with the same initial setting but now does.