Timing/mechanical advance conundrum....

[kawahonda]

A single point isn't too much to take care of--as long as you are using very good quality points such as Accel. The usual "nicer" ones from RockAuto are not good enough. The problem however, is that the Accel ones are no longer made (I only have one NOS backup set) so I may be forced to go electronic soon. The big reason is I put on about 1,000 miles a year on points, so that means as long as all is setup perfectly, I don't really mess with them much. To be honest, I haven't touched my dwell in 12 months (other than what I just did which required me to fuss with it) so that's pretty good!

Depending on what he finds, it may force my hand into go Pertronix I or Pertronix II. Both of my dizzy guys are huge proponents of Petronix. It also retains the stock look.

My guess is that it's something simple. But it's a pain in the ass to resolve in a car. He'll get it on Thursday and I'll update you guys on what he finds. If he's needing to replace the points for whatever reason, then I'll probably just go with an Ignitor.  Not sure which ignitor to go with though--I'm thinking the Igniter II because of the overload protection and and the adaptable dwell.

[RJChallenger]

Are Accel single points the same points as the ones you would find in dual point distributors??  If so, I have a distributor that hasn't been used since the late 80's or early 90's. I had put new points and condenser back then and never really used it, they should be like new. There yours   if you need them . PM me if your interested. Good luck

[kawahonda]

Got an update today. It's sitting in a good place. Will hear more soon.

@RJChallenger, not sure on that one. Good question though. I should be good...I have a NOS Acel Point/Condenser in package still. Thanks so much for the offer.

Depending on what he finds, I may just go Petronix II.

[Kowal]

Sorry to be catching this thread late...

Yes, the FBO plates rattle.   They also can hang up a bit depending on tolerances.   I have a Sun machine and have played with quite a few distributors.   Having said all that, they do work.   

I agree with the earlier comments that you were probably getting a little bit of advance between 0 and 800 rpm.   I am playing with a distributor right now that clearly is doing that, I am probably going to recurve it as a result as it is a problem in the car when trying to consistently set idle.

I think for a street car 34 is a little much on today's gas.   I try to stay around 32 or so in total mechanical, seems to stay out of the problem areas when using today's pump gas.   

On the vacuum can, I do run them, but I turn the screw inside the can almost all the way CCW so the vacuum kicks in as late as possible, gets it away from some of the part throttle transition issues but still using the help from the vacuum in some situations.    Summit carries a really nice line of vacuum cans from Standard if I remember correctly that have been repeatable and show the total advance on the arm just like stock units do.   I normally switch to those.

Finally, and here is where the crap hits the fan on future posts, I really can't see sticking with the points.    Pertronix does work well, though to get the real advantage from them you have to move up the food chain to the II or III.   To stay with the Pertronix base unit you get the reliability but it is still an on/off switch.   I like having as little mods as I can on the harnesses so I have swung in to just a Mopar ECU hidden on the car, normally behind the headlights or somewhere convenient.   The Blue unit that Jegs sells was helped in its development by R Ehrenberg from Mopar Action.   I have been using these and they do seem to add more starting energy to the car, the total performance curve seems more "alive" than the Mopar orange or chrome units.   

[kawahonda]

Excellent post. He's had to do some maintenance on his Sun Machine, so he hasn't had a chance to look at it.

If the pre-advance shows up on the Sun Machine, then GREAT! That's something that I hope he will be on the lookout for.

[kawahonda]

Looks like he found a cracked retainer clip that mounts on the bottom. Because this is cracked, the timing will be sporadic. I am very glad I sent this off to him because I may have not seen this.

Does anyone have this part that they can ship?

[Chryco Psycho]

All good advice from Kowel
I believe cam & dynamic compression have a lot to do with the total timing # & I accept what the engine wants rather than a specific number , each engine is different .
I have mentioned before when I weld the slots in the advance plate I always weld the inner part of the slot to extend the springs & to prevent the timing wandering below 1000 rpm 

[kawahonda]

My latest distributor doesn't seem to have any wandering issues.

My last one, I did seem to notice that it was doing that. It's the only way to explain why I thought I was getting 22 mech advance with an 18 advance mech plate. Hopefully the tuner will use whatever method he's used to on getting that sorted out. The distributor he has has been blasted, rebuilt, recurved, and is now getting repaired/recurved and will stay OEM/Performance Points and it will stay with the 340 when I pull it out to rebuild the 340.

Curious on the 32 max-all in comment though. I feel like every engine/car/combo/location is different. For my car, 32 is pretty dead safe, but a tad lazy mid range and top end. Bottom end is...fine I guess, but could be a little more peppier. 33 total is absolute bare minimum where I'm happy, still no signs of pinging under full load. 34 is starting to get into the "I think I hear something faint?", but cannot fully reliably confirm, or tell if if my mind is playing tricks, and the only way I get into that situation is when I'm full load, 3rd gear, loaded down on the highway with a passenger...and I can't tell for sure. 34 total around town, peeling out, hard acceleration, zero pinging. But that isn't a load condition, although it's 99% where I drive.

So I basically leave mine at 34 since I am still tuning, because I have yet to really dial in the secondaries worth a hell yet. My primary circuit needed a 4-step increase over stock to really get rid of all stumble issues. My plugs still look a hair lean, but also "mean" as well. I've ran at 18 initial once when my mech was restricted to 14, no problem starting when hot, super peppy, and no ping for around town "foot" smashes or mid range acceleration--that was just purely a test of initial. Highest vacuum too.

However, 18 initial with 18 advance is too much I will admit (93 octane may be a different story). Just saying--my motor loves initial, and under no reason should it ever be below 16. And I think once I correctly fatten up the secondaries where they need to be (check out my tuning thread) and with more testing, 34 total may just be perfect in all conditions and temperatures.

I run 91 blended up here. There is 93 around, but it's just not worth hunting and fetching it.

Lots of people run their curves too fast (all in by 2000-2500RPM), which I don't think is correct for these heavier cars with restricted fuel. I bet if my curve was that fast, then I'd have problems at low-mid range at 34 total. So that plays a big part into it what a good total is as well.

[YellowThumper]

Reading thru all this was very informative. Kinda fun coincidence as I have been driving a "fun discussion" on another forum (Ford) about using port vacuum or signal vacuum.

Thanks for the detailing updates for progress.