I've searched for an hour-my google-fu must suck.

I've had the pleasure of cruising a local 'yard and have purchased a couple nice distributors for my 300. After cleaning them freeing up the centrifugal advance mechanisms, I noticed that both have different numbers: One is a 16/21 (R)
and the other is 12/14 (R).
What is the preferred plate? I realize that bothy are for different emission applications, but I'm curious to know which works better for a towing/hauling application.
I'm aware that the numbers refer to half of the mechanical advance, i.e. a 16R is clockwise rotation, 32 degrees advance.
I'll likely buy a spring set and attempt to recurve this dizzy myself, if only for fun.

Which one do I install?

 

A 300 is probably good with 36-38° total advance at 3,500 rpm, so assuming 10-12° static timing the 12/14 should be pretty spot on.

 

I think it really depends on your setup. The different plates were for different advance rates for auto vs. manual, 3.00 vs. 3.50 vs. 4.11 gears, etc. So, it's difficult to really just pick one that's best.

Do you know what base advance your setup likes?

6° + 2 * (16 plate) = 38°
10° + 2 * (14 plate) = 38°
14° + 2 * (12 plate) = 38°

Etc.

 

Since the thread is about distributors and the ds2 in particular, does anyone know where to get a bronze replacement bushing, and how to go about replacing it?

Wyoming: I found a good article about the ds2 dizzy, and it mentions the parts number of the Mr.Gasket spring kit to recurve. I thought it might help you. http://www.classicinlines.com/DSIIswap.asp

 

"...does anyone know where to get a bronze replacement bushing,..."

That subject came up on the FSP site several years ago IIRC but I don't recall where they were sourced.

 

I wanted to mention the independent guy who did my distributor, cleaned a j/y dizzy, bored shaft, new bronze bushings, recurved with print out map of the timing curve, for $175. With the Post Office having $12 parcel shipping, it makes out of state parts affordable.

Ignition Engineering | Distributor Recurving and Rebuilding or email @ sales@ignitionengineering.com

 

Re in"Car"nation High Performance - Services

That company re-curves distributors also.

 

My '84 has been converted from feedback carb and EEC-IV to a NOS Carter YF (from an '83) and DSII. I'm trying to get all I can out of it, but I have little interest in upgrades, i.e. cam, porting, intake or exhaust.
My priorities for this truck are mileage, power, and reliability, in that orde

Transmission is a NP435, and final drive is 3.55. It'll be pretty rare for this engine to spin up past 3500, and rarely past 3200. 3200=75 mph in 4th gear.

Here's what I've done to date:
I replaced the new Autozone Duralast dizzy Bad pickup coil, couldn't find one in Gillette, so I bought a whole dizzy) and replaced it with a NAPA reman (prolly Cardone). Timed it to 14°, test drove, and got a little bit of spark knock at 75-80 mph. Back to the shop, backed the timing off to 12°, test drove again. This time, there was very little discernible spark knock, so I've left it. Funny thing-with the Duralast dizzy, I was unable to get it to stop knocking unless I turned the timing down to 2 or 3°.
I'm not sure how to check total timing-I lack a fancy timing light with the dial on the back: I presume that's the tool needed.
I may swap in two other distributors that I have for the education of it: one has a 16/21 advance plate, and the other has a 12/15 plate I think. I've purchased both at a local yard, cleaned them up, and found both to have very tight bushings. One (the 12/15) appears to be a reman.
Both have nice tight advance plate bushings as well.
From your post though, it sounds a bit like the numbers don't matter so long as the end result (total timing) is the same. Right?
Okay, I'll stop here, for now with the wall of text.

 

Probably no worries with either distributor in a stock engine at those speeds.

A dial back light is ideal but you can at least check timing against rpm as far as you can see it on the timing marker. Or mark the balancer every 5° past the timing marker and add/subract. With a stock distributor in a stock engine it should be pretty close to ideal.

 

I, too, just have the cheapie light, so what I did was get a little file and then rotate the harmonic balancer until the timing mark on the balancer was on the 10° mark. Once it was, I put a notch on the balancer at the 0° mark. Rotate again until the new mark is at the 10° mark, and then put another notch at the 0°. Etc.

That way, I have marks for 0° all the way up to 60°.

When you look at the timing on the engine you just reverse how you'd normally read it by using the 0° timing mark on the block as the base and seeing where it lines up with the new marks you've made.

If it's half way between mark 3 and 4, you know you're at around 25° timing (since the first mark = 0°, second = 10, third = 20, 4th = 30, etc.)

This way, you can get a timing map of your engine by seeing what timing it is at for the entire RPM range. Plus, when you leave it at idle, put a vacuum pump on the vacuum advance and see how much it advances for every lb of vacuum. That'll show you how fast your vacuum advance comes in.


As for initial vs. peak timing, a lot depends on your setup. Some engines just don't like a lot of initial timing (a common symptom is kick back on the starter), some love it. That's why you base it off of the initial.

 

After studing the paper on DS2 distributor by Classic inlines, appears by decreasing the spring tension on the weights, the rate of spark advance increases, improving throttle response.

 

That's recurving a distributor in a nutshell - changing springs until you get a curve that meets the engine's needs. Adjusting to bring on full advance sooner may or may not help throttle response depending on a host of variables.

On a more or less stock vehicle I doubt there's much to be gained from recurving - the factory setting is going to be close to ideal as far as economy, performance, and safety (i.e. detonation).

 

That's genius. I'm sure I'd have never thought of that. Are you from Russia? Seems those guys are always coming up with creative ways to do things.
Thanks for the great idea.
I'm off to experiment.

 

AB isn't from Russia...but, IIRC he may have gone to school in Moscow


Idaho.

 

Lol, yes, Moscow, Idaho's about the closest I've been.

It was really one of those ideas that just sort of came together on their own. I kept looking at those balancer timing strips you can buy and stick to the balancer(Timing Tape), but the edge of our balancers are really thin, so they wouldn't fit.

So I tried to calculate how far each increment of 10° would be and wasted a bunch of time with all this math and measuring the diameter of the balancer and figuring out how many fractions of an inch each mark would be, etc. etc. and then finally realized there's already a measure of 10° right on the engine...

A little file and 5 minutes and all the marks were made.

Hope it works out for you!