I just installed an NOS electronic distributor PN 3874876 (super 6, I think). Anyway, I've got the mechanical portion of the advance working great with the lighter of the two stock springs plus one light spring from a parts distributor I had laying around. It's a 9R mechanical governor.

The problem is the Vac advance - no matter what I do it pings on the freeway between 1/8 and 1/2 throttle unless I retard the distributor so far that it kills the low-end performance. I'm running a little blind here because I don't have an advance timing light (which I intend to cure soon).

The vac can is marked 11.0R - there's a PN on it but I forgot to write it down. From the parts distributors I have access to one marked 8.5R and one marked 10R.

The previous distributor installed on the car was a similar 9R mechanical one with an 8.5R vacuum can.

The easy thing to do is just install the 8.5R can and call it good but i can't help but feel that I can get more mileage out of it by making the 11.0R can work...

PS I've tried running it screwed in all the way (5 turns) and out 6 turns from where it started. Out is definitely better.

I hate all this stuff, i'm used to EFI where I can just tell the ECU what to do with the timing under the given conditions, and I'm used to dealing with electronic knock sensing. There's a reason OEMs went to electronic timing control.

That's the way things were and it's like an art, you have to get used to the 'media' to paint a good picture... the other way around playing with these things is getting an MSD-7, etc... and using the laptop to set the timing...

Good luck on the can swaps and finding the 'right one'...

-D.idiot

LOL, thanks - I know where i need to be but it seems like a pain to get there. i need to get a better timing light first.

With out a dial back timing light you don't know how much mechanical plus inital you have dialed in. My guess is that if you have a 9R or a 15R governor (long slots) and your springs may be too light.

The can should be screwed out about 4 turns or more to get in the pocket. That way it won't be engaged when you step on it or at an idle, but fully in at cruise.

Can you document how much initial your running and how much mechanical your getting at 2000 or 2500 or 3000 rpm with the pod unplugged?

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

GO TO THE LIGHT............GOOOOOOOOOOO TOOOO THE LIIIIGGHHTT:shock:

Very difficult to do this without proper tools - include a vacuum gauge with this, if you do not already have one.

Once figured out it is quite fun.

I Indexed my balancer in 5 degree intervals to help me set my timing

_________________
Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars

See here for vacuum can info

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks guys - it's a 9R governor. I'll get a proper light and get back to you.

As for the can it's the OEM can so I don't know how that compares to the list of aftermarket ones.

OK, finally got a light and collected some data.

Before: 11R can, 6 screws out, 9R governor w/modified light springs:
idle to 800 rpm - 2 degrees
1750 rpm - 20 degrees

It pinged on the highway between 1/8 and 1/4 throttle around 65 mph, but would pull through the pinging with more throttle opening. It was not a transient issue, it happened even if i held the throttle there.

The advance seemed a little too aggressive, and the base timing too retarded so I swapped the ultra-light spring I had for a heavier one from a different electronic distributor and set the base timing at 10 degrees as recommended on the forum.

After: 11R can, 6 screws out, 9R governor w/modified light springs
idle to 1000 rpm - 10 degrees
1800 rpm 20 degrees
2300 rpm 25 degrees
3000 rpm 28 degrees

With the vac. can connected it pinged worse than before on the freeway (duh, whole thing upped 10 degrees) but was amazing around town. The midrange was back!

Disconnected the can it was perfect at all speed/rpm points I could hit.

So I swapped to a long-arm 10.0 can I had sitting around and retimed it the same as above. Now it is MUCH worse. The 10.0 can is more sensitive and this thing pings all over the place. Even worse, I can't seem to get an allen wrench in the vac. hole, so I can't get the sensitivity back down.

Anyway, that's where I'm at now. I disconnected the vac. advance for now. I'm thinking that since the car is geared so low, maybe I'm running at the end of the mechanical advance at cruise speeds and there just isn't room for much vac. advance above that rpm.

I have a 8.5R short-arm vac. can I'll try next.

What's the difference between the short-arm and long-arm cans?

The long arm pods are for point dizzies and don't quite work so well with the EI distributor I've found... it kind of changes the advance in a not so nice way...

Looks like your springs aren't dialed in right, as well as you have not mapped your vacc. advance at all... vacc. hand pump to map the pod's response and driving with a vacc. gauge is going to be the key here....
adjusting the vacc. pod range without seeing where things go using a vacc. hand pump is taking shots in the dark... if you adjusted it incorrectly, you could have a pod that is in almost all the time, which would explain a fair bit.


I think we also have another problem, if your total timing with the vacc. can is only 28 degrees something is not right (hopefully not a slipped balancer). If your advance is 10 degrees base timing, then 28 degrees of mech advance and you have a pod kicking in another 22... yep that's wayyyy too much....

Did you get to check your plugs during the pinging phase? What color were they... what carb and jetting are we running?

-D.Idiot

robertbob,

It is great to see another member of the recurve club trying out some things....but as DI so kindly put it, you are "taking shots in the dark".
Not all a bad thing, but the chances of you getting a solution approximate zero, as on the proverbial blind hog finding peanuts ever one in a while. And of course they can smell!

While you have some numbers you don't really have data. In several threads I, and others have posted tables of turns out vs. vac range for the common cans. Useful to match your experiments with ONCE you make plots of advance vs. rpm with NO vacuum. You need a dial back light and a tach to do this. Plot them as Emsvitil did for us a long time ago. Having some base plots you then redo it...with the vac advance can hooked up.

You have got to collect information systematically to have usable data. The problem with swapping cans and turning them in and out without knowing what their ranges of vac addition are in terms of inches of vac per turn out is that you will have to do six times the work.

That is, if your can is able to be turned out six turns and you don't know what the range of vac per turn is, then you have to plot your curve with no turns out, then one turn out, then two turns out, and so on til you plot curves six turns out. The better approach in my opinion is to plot a base curve and see when you want vac to come in and out. Pick a can, turn it to that range, and see what happens on the road.

Toss out those points cans, well, cut one open to learn how they work and toss the rest. For my purposes I go back and forth between a 9 can and an 11 can. I just put in a wideband AFR to collect finer information on the tuning...but you aren't there yet and may never want to go that far. If mine was running as well as yours seems to have been once, I would go to high test gas and once knowing the range of when vac kicks in, I would then just adjust the can...Stick with what was working to start.

rock
'64d100

All of the above numbers are WITHOUT vac advance. The 11R can kicks in right off idle, if that means anything. w/out vac. advance it's 10 degrees base, 28 degrees fully advanced on the springs only. W/vac advance just add 22 degrees to everything; the vac. can kicks in right off idle.

I don't have a vac. gauge on the car but the 11R vac. advance starts to move at 8 in hg with a hand pump and maxes at around 12 in hg. The 10.0 can comes in at something like 2 in hg.

I did a plug chop and the plugs were evenly brown - stock BBS carter, stock jetting, stock 166,000 mile block & head.

I have an LC-1 wideband but don't really care to put a bung in this car's exhaust, it's no racer! I'm just trying to get decent performance without pinging. I'm coming from an EFI world so this is incredibly frustrating for me.

I think the best plan is like what Rock says - go back to what worked right. In my case it was the 8.5R vac. can with the same springs and a 9R governor that I have now.

ditched the long-arm can and went back to the 11R one because the 8.5R can I have has a stripped/broken adjustment screw. Now screwed all the way out, i'll just go back to retarding the timing a little to get rid of what ping remains.

but it's a tuner! I use the narrow band cheapies to just see what's happening while driving... with a vacc. gauge at the same time you can get the 'gist' of what's going on and why.....

What springs are you using on the mech advance... I get the feeling we are going to be looking for something that will limit the advance a bit down low so the vacc. adv at high vacc. doesn't compound the amount of timing you have going... With a BBS one barrel we are really looking at a total timing number of 44-47 tops... your engine is very limited by the carb and exhaust...

This is how things were when I was a kid, and it's not 'bad', it really takes strong analytical and mechanical skills to hammer things out... think about how much fun your computer controlled cars have after they get 'blipped' by $40 of electronic scrambler from the cops (or mad scientists like me....)

Keep at it, you're getting there...

-D.idiot

Your Springs...

You replaced the heavy long looped spring with a lighter spring - am I right?

I have the same combo but swapped out the stock light spring for a lighter one from my transdapt kit - the other way round mine pinged all over the place

With that done I dialed in my vac can

_________________
Regards,
Fanie Gerber
It's never junk, it's just a part you're not currently using

http://www.valiant50.co.za
Just say I own a few Mopars

Right now I have the light spring that was in the super six distributor originally plus the heavy looped spring from the previous electronic distributor (which also had a 9R governor). I think the light spring is blue. I have another blue spring that came from the other EI dist, and a slightly stiffer light spring from a points distributor.

I'm thinking of swapping the ultra-light spring in there now with one of the stiffer light springs to bring the first 10 deg of the advance in later (it's in by 1800 now), at least if that is how it works...