Few do ... If his distributor is stock and never been recurved he is not going to be able to get his initial up to 16 plus degrees and not have his total mechanical below 45 ... Stock distributors usually have 30 degrees of mechanical advance built into them.


I'm not even sure he has said what distributor he has ??

Understood,
I wanted to make sure it wasn't active at idle.

I have a stock distributor, but I have no idea what the previous owners did to it in the past. I'm tearing into it now.

That's the first place to start , without that knowledge you , or anyone else , can't possibly know what to do .

Is it points or electronic ?

With some long thin needle nose pliers you can spread the clip enough so you can lift it out with out mangling it (might take (6) "spreading" attempts to get it wider than the nub tho I've spread it some then grabbed a vertical leg & ripped it around to the open side & up in one motion & reused em many times. OE would be a light spring and a heavy spring with an elongated loop on one end and the plate will have a number on it (underneath) for the amt of (dist) adv it has (the slot length(s). I would highly suggest ordering the FBO plate/springs which I believe you already have as it is a must have. We have the initial finalized & the plate will set the total then we can move on to the springs then on to the can. One caveat, the slot plate always want to come up off of the weight nubs which is a real pain if the (2) thin round base plates are in place so ANYTIME you are removing the reluctor up off the shaft ALWAYS press down on the top center shaft with your thumb on your free hand and when removing the rotor press on the reluctor underneath it. EDIT Yes I had ASSuMEd that it was electronic! MORE EDIT then we will address rotor tip clearance and Rotor Phasing (how could I forget that) and reduce lower shaft axial play to .005"

Most of the stock Mopar OEM distributors will have the amount of mechanical advance stamp (usually from 10 to 14 camshaft degrees(with a R or L after the numbers) which is twice as much degrees on the crankshaft ) onto the bottom of the advance plate. The advance plate is what the rotor rides on, to shorten or reduce the amount of mechanical advance you will need to shorten those slots equally. For instance if the number is 13 that means you have a maximum of 26 degrees crankshaft advance with that distributor, I measure the length of the slot and the diameter of the pins on the advance wieghts and subtract that from the slot length, the length of the remaining slot can be divided by the 26 for the amount to see how much each degree equals in thousands and shorten the slot up by the amount you want to have. For instance say the total slot length is .750 and the pin diameter is .250 so the remaining slot length is .500, divide 26 into .500 to get the amount in thousands each degree is, which on my calculator is .01923 rounded to the fourth place after the decimal point. So if I wanted to have 16 degrees mechanical advance I would shorten up the slot to be .30768 or rounded off at .307 So if you do that and set the initial timing at 16 degrees BTDC you would have 32 degrees total timing or if you set the initial at 18 BTDC you should have 34 degrees BTDC total timing. Hopefully you get the main thinking on this even though it is not dead nuts accurate on the actual measurements.

Robert,
OK I got the Plate-spring -book combo from FBO.
I am not sure where to start because there is no explanation given for the black, silver and gold spring. I know its change-and-test to get the right combo.(I have 2 MSD billets in my other cars so I get the overall concept)
In your experience, what plate/spring setting is a good starting point. Its only a street driven car, but unfortunately the cam drove me (through buy-try-buy-success) to a 2800 RPM stall converter.
thanks and very respectfully
vic

Vic (1) set the plate on the pair of rectangle slots that will give you 36 total (start with the 10 pair) then check total with can capped. (2) Keep the light OE spring in there & sub in the lightest one of the (3) FBO springs for a start & romp on it up thru the gears & if it pings then sub in the next heavier one & repeat. You want to be a bit under the pinging point on your hottest/driest day up thru the gears. slight pinging can be hard to hear sometimes and there is silent ping so just stay a bit under it as pinging is extremely damaging. (4) for a stable/repeatable idle you also want the springs/slots to not start advancing any lower than 100-200 RPM above your hot in drive idle speed which is what the eng will see at the stoplight (in other words so you ain't into the springs while idling. A friend has the "tuning to win" booklet & I was not impressed by it. it'd be good for a strickly 1/4 mile drag racer only imnho but I did glean a few good tidbits from it. We have the initial finalized & we're on the slots then the springs then we'll hook up the can & work with it

sounds like a good plan!

Robert,
Done!
10 on the plate and one light FBO spring. 16 initial.
took car out for a cruise and every thing seems nice and responsive.
But I do I get a backfire every time when I stomp on it hard enough to get the manifold vacuum to drop around 5"hg.
All of my carb diagnosis books that discuss backfire say to check choke plate binding or wires/plugs.
not sure if baking off vacuum advance will help ( retarded advance is usually associated with hesitation, but not backfiring in my books)
does this sound familiar? Any ideas?
Thank you
Vic.

you have 36 with the can capped? One backfire then it pulls hard (or not)?is that a backfire in the carb or out the tailpipe(s)? is the AP giving an immediate/healthy (quantity/duration) stream immediately on tip in (you jerk the throttle & it is squirting)?

Yes, with it capped (dependent on the accuracy of my digital timing light)
But I made this cruise with the vacuum advance connected
I'm pretty sure it is a tail pipe back fire, it sounds like its coming from the pass side. I didn't have the nerve to see if it pulls through the backfire(I didn't think it was recommended). but it did happen 3 separate times

I'll have to check he AP in the morning and report back

yeah we gotta get the backfire taken first. More info on that, at what RPM /amt of throttle (part or WOT) is it doing it/just once or multiple times

OK, AP squirter looks good.

The backfire events were a single POP at WOT (or close to it). I got it to happen 3 more times.
Each time I was cruising at 45-55 mph. When I stomped on the gas quickly the car would backfire. I would hear only one POP. I have a vacuum gage in the car, so I watched it after the first back fire. When I would rapidly stomp on the accelerator pedal the manifold vacuum dropped to 5 " Hg or below and the POP was heard. then I tried a deliberate but slower acceleration and I could get to 5 Hg without a POP. I didn't note the rpms, I'll have test it again to get to back on that.

disconnect the can & retry it & see if it still pops (rotor phasing issue). the floats are set correct & you said the squirt was pretty healthy? I'm trying to decipher if it is a lean condition (which it sure sounds like) to continue further. EDIT will it rev above 2350 RPM like it was stuck at originally?

I will re test without the vacuum advance can and report back.
yes, it gets above 2350, just not with the idle set screw, I needed to use the accelerator pedal.
Seems pretty dumb on my part, the idle screw isn't long enough to get beyond 2350, but I could have just used a helper at the gas pedal

Robert,
I haven't forgotten to get back to you. I has been raining here in Maryland almost every day since mid May, so its difficult to find a good time to test and tune. I will run it with out the can as soon as can ad let you know the results.
thanks
Vic

No rush bro

Did you set your idle mix screws to max vacuum? Take them all out 1/4 turn at a time for max vacuum then put back in 1/4 turn. Start all at 1.5 turns out. All should end up set at same number of turns out.. After setting timing do again. Correct Robert?
Stop turning out idle screws to raise idle..
Where are u in MD. Our weather sucks.

Robert.
I got a day without rain!
I drove it with vacuum advance disconnected and it still popped/backfired.
I will report what I noted, but its not very technical.
The pop only when I nailed it rapidly after about 10 min of diving. It happenedd on a level or slightly downhill grade and the engine was around 4000-4500 rpm(, by the time I looked down it was falling through 3500 rpm.
This is NOT the way I intend to treat this car on a daily basis, but I will have to get up therein RPMs to pass occasionally

so it seems as if the vacuum advance is not the culprit, but I'm not sure.
Whats my next move?
thanks
Vic