Timing/mechanical advance conundrum....

[kawahonda]

I did.

Second pic is after 30% of filing.

Oh, you're saying the inner wall slot? (Closest to the shaft) How come? That's where it rests at idle..

[Chryco Psycho]

One other thing to mention here.... With my stock dizzy springs, I was getting 5 degrees of 'wander' in timing at idle between 800-900 rpm... it was just at the threshold of mechanical advance down that low...

When I made my plate, I shortened the slots from the inside, so the springs were a smidge tighter at idle, and it doesn't start advancing until I get to 1200 rpm...

(Time to mention Chryco here for that tip!)

Right here

[kawahonda]

Oh. You're talking supplemental, instead of "instead".

Mine isn't lose. I have to expand out the tabs a little bit in order to fit it on. Mine already is a tight fit in the "home position".

One thing at a time. Mine does not wander at 800-900 RPM.

If I welded both sides I would have a damned mess and would have lost a starting position. I'd be going right back into trial and error again. This is not the time for trial and error. .357" should be my new slot width.

I'm also confused that if I did have the "wandering" issue, how would enlarging the "inner" wall help with that? It seems to me that you would increase wandering (wandering because it is advancing when it shouldn't be). I'd think filing away the inner wall will decrease "wandering", not building up the inner wall.....

EDIT:

(sorry, beer club meeting and had a few beers):

If you're talking about "instead" then I can see how it may make sense. Basically, you're telling the distributor to go ahead and advance slightly via the mechanical action because you're applying more pressure by increasing the inner wall.

Makes sense, but I don't see how one is better than the other. If one were getting "wandering" at idle, then inner wall makes sense. If one doesn't have that issue, then it's probably not the best attack method.

I'd rather leave the mechanical out of it when setting idle initial. My recurve is 3200 RPM (meaning stronger springs are installed, slightly) which is great for 91 fuel and to help safeguard against pinging. Once I get to 18 mech instead of 16 mech, that gives me headroom to work on the initial as we both tune the carb Neil!

[Chryco Psycho]

With the factory springs one spring is loose at rest , by adding to the inside I believe you get a more stable curve with the springs slightly stretched , I would not change what you have done now unless you had a second advance plate to weld

[73_Cuda_4_Me]

It is instead of doing the outside. You still have the same length of slot, so same amount of net mechanical advance. Like you state, you are 'riding the posts' at idle anyway, so moving insides 'out' makes you ride the posts a little more, tightening the springs - shifting the advance curve RPM-wise only.

With stronger cams, you need a little more idle speed... the stock spring setup starts advancing at 800-900... yours may be solid, but I'll bet if you check timing, you will see you are already getting some advance curve at idle, and if you lower idle speed it will retard the mark.

Doing the inner doesn't matter timing wise... yes, you put the dizzy mechanically into advance curve a little, but you set the actual initial timing once the dizzy is in the engine. You still rotate to set timing at your ideal 18, slots will still be for total .357", and you have your range at both ends.

All I know is that it seemed like my timing was always variable, alot having to do with running larger cam with an automatic... putting it in drive dropped the rpm by 300-400 rpm, and I'd see timing shift by 10 degrees!!!

By doing the insides, I ensure that I am not mechanically advancing from initial setting until I get above 1200, and still end up at 36 with initial set at 18.

[Chryco Psycho]

You explained it better than I did , Thanks @73_Cuda_4_Me 

[73_Cuda_4_Me]

That means a lot, Chryco! Thank you!

Just passing the knowledge I got from YOU along...!

       

[Chryco Psycho]

I have always been better at doing the work & understanding why  rather than explaining it 

[73_Cuda_4_Me]

It's yours and so many other members of this community helping other members that make it so helpful and valued to all the rest of us...

You all give us such big shoes to fill when the time comes and we can help someone else out!

Just know that it is REALLY appreciated!

[kawahonda]

Well, was out in the garage for quite awhile today.

I tested .357, and it landed me at 15 mechanical.

I filed to .368 and got at 16 mechanical. At this point, I started noticing funkiness with my dwell.

At idle it would generally stays at 31.5, but I notice during revving the dwell would rise to 33-34, and then it would cut to 28.

This means time to stop playing with mechanical and figure out what is going on with this first.

Any ideas? I have two accessories hooked up to my coil (timing light and dwell meter), but that hasn't caused an issue before. I suppose I can try to only hook the dwell meter only to it.

[kawahonda]

Boxing it up and sending it out to my friend at Hillside Auto in Klamath Falls. He has 3 sun machines, and is really good at distributors. Figure we're kinda in fine tuning phase here. He's been along for the the ride every step of the way, and wants to get his hands on it. He will check it all around.

What f$@%ing sucks is that now I have nothing to do for a week.

[Chryco Psycho]

Dwell fluctuation can be a weak spring on the points allowing them to float or a worn bushing allowing the shaft to move or a worn cam , it would be close to 50 years old now 

[kawahonda]

Well, now that I've had time to think....which means a few beers and a 24 hour break from the garage. I spent 8-10 hours yesterday and made some progress, but then it all went to hell.

1) Distributor is shipped to an expert. With tools that I don't have. An engine is a tool, but it takes LOTS of trial and error to get exact which is OK, but when your DWELL goes crap, then you have bigger problems.

2) The first time I dissembled the distributor, I did not know about removing the felt pad and the clip. This means I pried cam against the plate. I pried VERY carefully, a few times, until I decided it wasn't worth adding more force. I really hope this action did not screw up what I'm seeing now. The reason I don't think it did is because the timing did not do this at idle when I assembled it the second time around. It only started happening after the 3rd or 4th time around....

3) Yep, I F$*@ed u, somewhere, somehow. It may be very simple. It may not be. It may just be time for an Ignitor I or Ignitor II if it cannot be set back stable with Accel points. Whatever it takes to get it to read 100% stable initial, and 100% stable total, then I'm game. More and more it appears Neil is correct. It feels like it's on the verge of being a little scatter-y each time I fuss with it.

A Sun machine is MUCH better than a car. it will be diagnosed, fine tuned before it comes back. I am drinking in sorrow. He's offering free-of-charge. Great Ford guy....

[Chryco Psycho]

Education Always costs $$ all of us have learned & screwed up along the way , really no big deal , you will get it fixed & keep moving forward 

[71383bee]

Yep been there done that. Good thing these cars were mass produced!  Plus your working on a part that's pretty common. Lots of options if it's truly broke. 

Out of curiosity why haven't you switched to an electronic setup yet?  Just looking to stay 100% stock? 


Sent from my iPhone using Tapatalk