Hard running condition super stumped

[gadget73]

The shaft should rotate freely, but it should not slop around. There are a pair of bushings in there, and if they are worn the shaft will wobble, which makes the spark timing go stupid. There is also an advance mechanism in there, both vacuum and centrifugal. If the centrifugal weighs are messed up, that could also cause you some problems. You should be able to pull the plate where the pickup sits out and inspect the mechanism. Its been an extremely long time since I was into a Duraspark dizzy but I want to say there is a plate in there that limits the advance, a couple of weights and a couple of springs. You should be able to pull the weights out and see the distributor shaft rotate a bit. If the weighs are stuck out, probably the springs broke or it rusted up. Chebbys were good for rusty advance mechanisms or flats worn onto the weighs that caused them to jam.


Um, you said 8 degrees after top dead center. It should be around 10 before top dead center. If you're 20 degrees off whre it belongs its gonna not run for shit.

The idle is way high. 800 rpm is at the high end of where I'd want to see, 1100 in gear is much too much. Around 700 is where I'd expect it to be.

Set the timing with the vacuum unhooked. It sounds about right honestly towards the end of the video when you unhooked it.

That full manifold vacuum advance shit always confused me. I know Ferd did that for some reason, but I was always used to ported vacuum where you had basically squat at idle and it came on more as you got into the throttle. If you've got the option, maybe try swapping the connection to ported.

[johnunit]

The shaft should rotate freely, but it should not slop around. There are a pair of bushings in there, and if they are worn the shaft will wobble, which makes the spark timing go stupid. There is also an advance mechanism in there, both vacuum and centrifugal. If the centrifugal weighs are messed up, that could also cause you some problems. You should be able to pull the plate where the pickup sits out and inspect the mechanism. Its been an extremely long time since I was into a Duraspark dizzy but I want to say there is a plate in there that limits the advance, a couple of weights and a couple of springs. You should be able to pull the weights out and see the distributor shaft rotate a bit. If the weighs are stuck out, probably the springs broke or it rusted up. Chebbys were good for rusty advance mechanisms or flats worn onto the weighs that caused them to jam.

Ah ok. That sounds like stuff I've all dealt with and the timing is stable going by the light. I've had the distributor apart and everything moves nicely.

Um, you said 8 degrees after top dead center. It should be around 10 before top dead center. If you're 20 degrees off whre it belongs its gonna not run for shit.

The idle is way high. 800 rpm is at the high end of where I'd want to see, 1100 in gear is much too much. Around 700 is where I'd expect it to be.

I've tried everything from 8 to 15 degrees without vacuum. Doesn't make a noticeable difference in this context other than being harder to start. I started at 12 and have just been messing with it to see if something works.

To clarify, those idle speeds are in park/neutral. 1100 is about where I was to have 750-800 in gear, before all these problems happened.

Set the timing with the vacuum unhooked. It sounds about right honestly towards the end of the video when you unhooked it.

That full manifold vacuum advance shit always confused me. I know Ferd did that for some reason, but I was always used to ported vacuum where you had basically squat at idle and it came on more as you got into the throttle. If you've got the option, maybe try swapping the connection to ported.

I may try swapping to ported, but it all did work nicely before. I'm mostly trying to get back to the settings and combination that ran really nicely for about 8k before the initial breakdown. I'm not sure I had everything right before but I can't divine a difference between how I have it now and how it was when it could cruise at 85mph and rip up to red line with no hesitation.

[gadget73]

Re-reading the initial post, I really have to suspect something is wrong in the distributor. If it was fine until something broke and required a pickup replacement, I'd go back and look at all of that stuff again.

[Tiggie]

I am not a duraspark expert but I do think they have a ignition retard function during cranking built in for some models. What color is the block where the wiring goes in the duraspark box? It sounds like your ignition retard feature is working backwards - although I am not sure if that's possible or why. Can the pick up be wired backwards? Found this info here http://www.fordmuscleforums.com/all-...2558?_k=qjgisg

Also I think I Have a duraspark box hanging around from my 82 spare parts. If it's a match to yours, you can have it for free if you want to pay shipping. May help trouble shoot? I always carried in the trunk just in case.

[johnunit]

I've swapped back and forth between two ignition boxes to confirm they're not the issue, but I think I did end up fixing a connection or two in the initial set of repairs so I guess I should look at whether I got something backwards somehow. If the ignition retard is backwards somehow that would be along the lines of what gadget is suggesting, going back to when it all started.

It definitely is acting like the timing retard is reversed, too much when I crank and maybe not enough when running.


Edit: and they're the blue plug ones, one of them being the exact unit I was running before my troubles began.

[gadget73]

There is a white and a red power feed, red is your normal key-on hot, where white is the starting hot. Not sure if thats what makes the spark retard do it's thing, but it would be sensible. If those are reversed or if the white was constantly powered it may do dumb stuff.

[johnunit]

White is on when cranking and red is on in run and when cranking. Guessing that's how it should be.

[gadget73]

yeah thats how it should be. Red needs power all the time or it no chooch. Some quick google-fu says the white is indeed the spark retard wire, and powering it pulls the timing back to make it easier to crank. No power to the white puts the timing at "normal" and its controlled entirely by the mechanicals in the distributor at that point.

[johnunit]

That's what I figured. Back to the drawing board.

[gadget73]

Just make sure its not on some sort of leaky connection. Not sure how touchy it is, but if there is any voltage there it may put it into spark retard mode. Confirm with a digital volt meter that its 0 volts when running.