I nabbed 2 NOS ditributors of ebay for $60 each. I tore into them to find out how much mechanical advance they had. The last slant six distributor I did already had a 9* (18*) advance rotor in it. Both of these distributors had 15* (30*) rotors, so I had to reduce the slots to give me the 9* (18*) or 10* (20*) I wanted.
First I had to remove the cap, rotor, vaccum advance can (2 screws), advance plate (2 screws), pry the 6 pointed reluctor off, remove the 'C' clip (this will male you testy, keep downward tension on the shaft and pry over each of the 'C' clip tabs till it works its way out of the groove it's in, the downward pressure will keep it from popping back in the groove when prying back and forth on the 'C' clip), remove advance rotor. The drive gear can be left on and weights and springs can be left it. Change the springs to something lighter. I used the lightest spring in the Mr Gasket advance kit for a GM HEI dist. They will be OK for my race car, might be too light for my street car, I'll know by this weekend. Here the removed parts.



Here's the springs installed.



Next was to reduce the slots in the advance rotor. Stock was marked 15R, which is 15*, which gives a total of 30*, I think the R is for right rotation.



I brazed up the .475 long slot and filed it down to a length of .381.
Here are my calculations.
Slot .475
Slot limit stud .240
.475-.240=.235 of movement for 15*
I need 9*, so

.235 X
____ = __ 15X=.2125 X=.141 .141 movement+.240 stud= .381

15* 9*

I ended up with .385 on the dist for my race car, .398 for my street car. After brazing and filing it looked like this.



Installed back in.



Then I just reassembled. I'll wire my '68 V200 this weekend and test my results with a dial back timing light to see how close my calculations come to 19*-20* total mechanical advance and see if the springs aren't too light. And I may try it out at the 1/8 mile strip in Lakeland FL.

Cecil

I can't get the equation spaced out right. I'll try this.


.235 --- X
____-=- __ -------15X=.2125-----X=.141-----.141+.240stud=.381

15* --- 9*


.381 slot size needed.


Cecil

I bought the same NOS distributor from the same seller and performed the exact same modifications. Also used the same calculations. I dialed-in 14 degrees of distributor advance which allows me to use about 15 initial. That vacuum advance unit should be adjustable.

Mitch

I didn't check to see if it had an adjusting screw in the diaphram but is marked 8.5* or 17* vacuum advance.



Cecil

so if you have a 15R advance rotor, and had 15* initial with no vac advance you have a total of 30* timing correct? and the springs just allow you to "time" the advance events correct?

Justin

P.S. Thanks Cecil, those pics help out alot of what to do! oh yeah, thanks for figuring out the math lol!

A 15* advance rotor and 15* initial will give 45* total, not counting vacuum advance. Since the cam turns at 1/2 engine RPM, 15* in the cam driven distributor will be 30* at the crank where you check timing.
I reduced the rotor to about 9.5*, which is 19* at the crank, along with 11*-13* initial will give 30*-32* total. Then add the 8.5* (17* at the crank) vacuum advance pod and advance at highway cruise is 30*+17*=47* or 32*+17*=49*.
I bought a remanufactored dist early this year, $45 at Advance Auto, and it had a 9* rotor, so all it needed was some lighter springs. It gave me 30* total with 12* initial. This NOS one for an appliction from around '74-'76, would have allowed 0* initial advance, not very good for performance but good for a truck that might be using low octane fuel have a heavy load on it at low RPMs.

Cecil

H'm. My brain must've slipped a tooth; I don't quite understand why this distributor "allows 0° initial advance". Can you clarify this, please? I'm betting I have the same distributor from the same seller -- P/N 3755042, right? -- and intend putting it in my 2bbl (soon to be twin SUs) street-driven '62 Lancer w/aluminum 225 and auto. The P3690789 kit comes with WAYYYYYYYY too much mechanical advance, WAYYYYYYY too fast/soon, for street use without pinging!

I've also just picked up one of the seldom-seen cast iron Prestolite Slant-6 distributors from a '64 Canadian Valiant and may do some tweaking with that. I had one of these from the factory in my '65, and that engine ran very well indeed.

Speaking of nonstandard distributors, does anyone know if Mallory made a SLant-6 distributor with vacuum advance? I've got a NOS dual-point unit , but it's mechanical advance only...

Mine came from Bill Rolik in NJ. He's a NHRA Super Stock racer and a '71 Cuda convertible enthusist.
If you have a dist with 30* mechanical advance and want to run 10* initial, you'll end up with 40* total which is way too much.
For a goal of 30*-32* total with 10* initial, a dist with 20*-22* mechanical advance is needed.
I have two distributors from the 3690789 kit in '82 and '84 D100s and they seem to have 20* mechanical built into them. They both have 10* initial and 30* total. What is your initial timing?

Cecil

Not to get off the beaten track here, but what do /6's really like? What I mean is like big block 383s like to have it [timing] all in by 2000rpm with a total of 36-38 depending on the build. They just buzz it up, time it and forget about what it falls at for idle. What do the /'s want? Anybody do a check in this department?

A few months back when I 'redid' my distributor Doc said the slant likes 32 initial+mechanical advance all in by 2300-2700 (with the last couple of degrees coming in a bit late), and like the other mopar mills, total with vaccuum advance should be in the 52-55 degree range. If the car is track bound I'm sure the mech advance will come in lower (some guys like 1200, others like the 1500-1800 range...)

Good pics Cecil, sadly if you're getting a remanf or replacement parts most don't come with the nice reference stamps like your's has (heck some of my OEM big block distributor advance governors weren't stamped either), which makes for some fun 'trial and error' with the dial back light...


-D.Idiot

As DI stated, a 225 SL6 does not like a lot of total advance, 28 to 32 degrees will get you the best power at WOT. I think this is a result of the long stroke on a small bore, you just don't need a lot of "flame travel" time like you would with a 4 inch ++ bore and a short dwell time stroke / rod ratio.

One thing a SL6 does like is a good amount of initial timing, especially when a performance cam is used, this is why the weight slots usually have to be reduced for a performance SL6.
DD

I didn't know Prestolite made a dist. for a slant. If it is like their V8 dist's they are deluxe pieces. The V8 dist's have ball-bearing'd advance plates! Ma Mopar put them in all their performance apps.

_________________
'66 Cuda 225/4spd
'66 Dart GT convertible 225/auto
'64 Dart GT 340/4spd

No ball-bearing breaker plate in the Prestolite distributors for the slant; they use copper sliders just like the Chrysler distributor. There was a center-pivot ball bearing dual-points breaker plate made for the aluminum-body Chrysler slant-6 distributor by, I believe, a company called Dyna-Flite, but I could be wrong on the name. I ran one of these in my '65 for awhile.

It worked. *shrug*

Yep, found it. Dynaflyte 503D, visible here:

http://www.vapinc.com/mopar/Distributor ... /main.html

How much mechanical advance does the Mopar Performance distributer have? I have a '65 Cuda and my mileage has dropped slightly after a number of changes including the distributer change. Is there anything I can do to the MP distributer to improve the mileage?