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nditiz1
Ok so I'm currently running the 123ignition dist on my 2056 with dual webers. I read the instructions and don't understand the mapping. I also don't know how it all works together. Can someone educate me on the vacuum adv and what curve would be best? As the rpm's increase it creates more vacuum thus creating more adv, but if I already have a curve setup to go from 12 degrees at idle to 28 degrees at 3000+ will the vacuum adv move the timing even higher once it is hooked up and mapped?
Mark Henry
On dual weber's you shouldn't run vacuum advance, dual carbs (or ITB's) have a piss poor vacuum signal and will likely only cause you headaches.
The more duration the cam has the worse it gets.

If you really want vacuum advance I would run the vacuum hoses to a central sealed box then to the dizzy. I'd also stick a .023 mig welder tip into the vacuum hose(s) to help even out the pulses.
Likely you'll have to tap the manifolds in a couple of different places and play around to find the best vacuum signal.

I won't be surprised if you end up capping/disabling the vacuum advance.
nditiz1
I'm not sure why Webers shouldn't use vacuum when they come from the factory with vacuum ports.

If I am going to use it I will only be using the vacuum port on cylinder 4 (off the carb) with an anti-pulse valve.

I'm getting the info from John of ACN.

Currently the carbs vac port is capped, but the dist is open (McMark - Never cap the vac port on a distributor)
bbrock
QUOTE(nditiz1 @ Jul 11 2018, 09:09 AM) *

I'm not sure why Webers shouldn't use vacuum when they come from the factory with vacuum ports.

If I am going to use it I will only be using the vacuum port on cylinder 4 (off the carb) with an anti-pulse valve.

I'm getting the info from John of ACN.

Currently the carbs vac port is capped, but the dist is open (McMark - Never cap the vac port on a distributor)


popcorn[1].gif Once again, I am wrestling with the same questions as you. I bought a Bosch 050 long ago with the intention of using with my Webers but now wondering if something with vacuum would be better. For your setup, I'm wondering why you are thinking of just using one port instead of Teeing both carb ports together for a better signal?? I don't know enough to know what, if any advantage there would be. Just curious and will be watching this thread closely. bye1.gif
rhodyguy
Isn't there a 123 that doesn't require a vac signal?
Mblizzard
To echo what Mark said, after running the 123ignition on my 2056, the vacuum advance is not necessary.

Look at the literature that shows the vacuum advance start, vacuum end, and degrees the vacuum is effective only over a short range and it is quickly overtaken by the programed advance.

As shown in the original Bosch dizzy information (note this is a representation of the curves and the values have to be doubled to read correctly) shows that at 3500 RPM you get a total of 22 degrees advance which matches the 123 numbers. Yes I know that you are thinking at 3500 rpm advance should be at 27 degree. True but the engine is not designed to fire at TDC so there are about 5 degrees to account for that fact.

Looking at the dashed line for vacuum advance it shows that the vacuum is not additive meaning it will never advance above the 22 degrees due to vacuum. It only helps the change occur faster.

On my 2056, I used the negative advance because as with the stock engine, with the timing set to give you 27 degrees at 3500 rpm it results in more timing at idle which will give you more RPM. The higher timing at idle gives you more RPM than the 900 you want so you can take some of that out using the negative vacuum settings if needed.

Using curve B allowed me to adjust the idle into the perfect range. You may or may not need to play with the negative vacuum depending on you idle adjustment.
DRPHIL914
So Mike, I will be installing mine soon, right after I get motor back in the car and have it running. Once I do that I will put this in, I just don't want too many variables at once, - but to clarify, when you had the d-jet stuff on your motor you ran which curve setting on the 123 dizzy?

Phil
BeatNavy
QUOTE(Philip W. @ Jul 11 2018, 01:21 PM) *

So Mike, I will be installing mine soon, right after I get motor back in the car and have it running. Once I do that I will put this in, I just don't want too many variables at once, - but to clarify, when you had the d-jet stuff on your motor you ran which curve setting on the 123 dizzy?

Phil

I'm running curve "B," Phil. 2056, D-Jet.

My experience is similar to Mike's. When I tried to run vacuum advance I couldn't get the idle low enough. Vacuum advance works over a short range from idle, and my performance is just fine.

DRPHIL914
ok that is where I will start. My idle was about 1000 before, so if its a bit more than 900 no big deal,

so now that we have eliminated the old trigger points, how about a more modern solution to the MPS??( I guess that would be a custom digital injection system like megasquirt or the like) just seems like there ought to be a way......
Mblizzard
QUOTE(Philip W. @ Jul 11 2018, 09:51 AM) *

ok that is where I will start. My idle was about 1000 before, so if its a bit more than 900 no big deal,

so now that we have eliminated the old trigger points, how about a more modern solution to the MPS??( I guess that would be a custom digital injection system like megasquirt or the like) just seems like there ought to be a way......


I ran B also.

Looked into the modern replacement for the MPS but no such thing.

Got you covered when you are ready to do the Micro Squirt!
Dave_Darling
QUOTE(Philip W. @ Jul 11 2018, 10:51 AM) *
...how about a more modern solution to the MPS??


Variable inductance depending on a vacuum signal is not a trivial thing to do with solid-state electronics, as far as I know. You're far better off going full-on digital EFI at that point, and ditching the D-jet.

--DD
nditiz1
The whole reason behind the want to use vacuum adv with the standard curve on the 123 is due to my webers having a lean hole. John from aircooled.net seems to think if I have more advance at light throttle (transition between idle and main circuit) then it wont lean out. I have several different jets and have tried several different combinations to fix this lean hole. The best one has been setting the idle to a 55, but then I'm running real rich. Also it only allows for a 1/4 turn out on the mixture screw for highest idle. If I have more advance during the transition it should help with the "leaning out" Correct me if I'm wrong here.
pete000
I am not using any vacuum on my 123
DRPHIL914
QUOTE(Mblizzard @ Jul 11 2018, 02:16 PM) *

QUOTE(Philip W. @ Jul 11 2018, 09:51 AM) *

ok that is where I will start. My idle was about 1000 before, so if its a bit more than 900 no big deal,

so now that we have eliminated the old trigger points, how about a more modern solution to the MPS??( I guess that would be a custom digital injection system like megasquirt or the like) just seems like there ought to be a way......


I ran B also.

Looked into the modern replacement for the MPS but no such thing.

Got you covered when you are ready to do the Micro Squirt!



posting a follow up to some questions that came up on this thread a few months ago. I finally got my 123ignition installed and put the pre-set program at "B". I was looking at the vac curves for these settings in the book, and it looks like B is set for max - at 2200 rpm, not 3500 , that would be "C" or "3" so that leaves me wondering if I could get bit better response on that setting? has anyone compared the 2 on a 2.0 stock motor?
I only got to take 2 short drives with the motor warmed up. Here are a couple impressions right off the bat: No more hesitation or skipping that I would feel before at idle and a slight hesitation sometimes on acceleration, VERY SMOOTH, but not quite as responsive on hard acceleration at @ 3500 to 5000, so is that due to the curve selection? Also, nice steady low idle @ 900 or so, with stock d I had a hard time getting idle down under 1000, and then only with moving back distributor and changing the advance. And boy is it sensitive! in adjusting the timing If the distributor move even just a degree or two it changes idle very quickly. It will be interesting to see how this will effect gas mileage. But the better ignition with no missing has to help both performance and mpg.
I am going to leave this a B for now, but may try C later on. If I understand the pre-sets correctly and how they are labled in the manual, B will give you max advance @ 2200rpm, where as C setting will deliver this advance at 3500rpm., and that should actually be closer to stock. My distributor does have the vac nosle sticking out , I would assume that since I have a 75 2.0 throttle body and it only has the one outlet, and that is for retard not advance? and if so it would be left off anyway?

Phil

ps - sorry for hijack but looks like thread was dead anyway biggrin.gif so hope you don't mind
Mblizzard
Phil

Don’t worry about the curve numbers. Set using the dizzy your max advance to be 27 at 3500. If your can’t get a good idle or it lacks power then change the curve.

So if you use B and lack power or it seems to be running poorly then go a curve that brings the advance later.

I was running 2056 so the B curve worked best but regardless of which curve you use set it so max advance is in at 3500.

If your nozzle on the throttle body has vacuum at idle then it is a retard. If it has vacuum on opening the throttle then it is advance.
DRPHIL914
QUOTE(Mblizzard @ Oct 29 2018, 08:27 AM) *

Phil

Don’t worry about the curve numbers. Set using the dizzy your max advance to be 27 at 3500. If your can’t get a good idle or it lacks power then change the curve.

So if you use B and lack power or it seems to be running poorly then go a curve that brings the advance later.

I was running 2056 so the B curve worked best but regardless of which curve you use set it so max advance is in at 3500.

If your nozzle on the throttle body has vacuum at idle then it is a retard. If it has vacuum on opening the throttle then it is advance.



what is the difference between the 2 and B ? both list same number dizzy . that part is unclear to me. on the chart the B lists Neg vac, along the "2" it lists same dizzy number but other numbers not neg vac. so that would be a car with no vac advance?
BeatNavy
Yes, IIRC the difference between curve 2 and curve B is the former has a vacuum advance, while the latter only uses retard.
DRPHIL914
QUOTE(BeatNavy @ Oct 29 2018, 10:23 AM) *

Yes, IIRC the difference between curve 2 and curve B is the former has a vacuum advance, while the latter only uses retard.

ok, I found the chart on line after a bit of digging and it shows the 1-8 vac advance setting as starting at 100mmhg and ending at 300mmhg(hitting max advance), where as on the chart under those headings for the A,B,C,D,E etc it just had a dash in both columns, so I thing you recall correctly.

that would lead me to believe that the advance in that case it preset, and that we could experiment with this a bit, but first thing I will do is to try the current setting of B, which is 2200rpm/22 degrees adv and then compare it to C, where the advance curve is programed for max at 3400/23, which I believe is closer to stock. I think I remember that Mike had said this helped his idle, mine is really low on the B so it might help to go to the C , but either way this seems to be so much smoother. I can tell you from the readings of the AF meter I am now not running so rich. I will be watching to see ho the oil and head temps are doing. I know being too advanced at high rpm is bad for the motor over the long term.
Dave97
Has anyone installed the Bluetooth model? What did you use for both advance curves? Mechanical and vacuum
pete000
I'm not using any vacuum advance on mine. Works great. The Ginther 914-4 race car didn't run any. No need...
914_teener
Not that I run carbs......I run D-jet.

In my opinion this is one of the better upgrades for drive ability that I have done to my car.

Once your AFR is right it is set and forget.

FWIW I do run the vacuum advance, but my car runs the stock cam and injection so I went with a different dizzy. Bluetooth is not available for the D-jet version.
DRPHIL914
QUOTE(914_teener @ Oct 30 2018, 12:59 AM) *

Not that I run carbs......I run D-jet.

In my opinion this is one of the better upgrades for drive ability that I have done to my car.

Once your AFR is right it is set and forget.

FWIW I do run the vacuum advance, but my car runs the stock cam and injection so I went with a different dizzy. Bluetooth is not available for the D-jet version.


which preset did you use B or C?
72hardtop
QUOTE(Mark Henry @ Jul 11 2018, 07:34 AM) *

On dual weber's you shouldn't run vacuum advance, dual carbs (or ITB's) have a piss poor vacuum signal and will likely only cause you headaches.
The more duration the cam has the worse it gets.

If you really want vacuum advance I would run the vacuum hoses to a central sealed box then to the dizzy. I'd also stick a .023 mig welder tip into the vacuum hose(s) to help even out the pulses.
Likely you'll have to tap the manifolds in a couple of different places and play around to find the best vacuum signal.

I won't be surprised if you end up capping/disabling the vacuum advance.


Not necessarily.

One must check with a vac gauge first and see.

With my set up a vac gauge showed ~10in of vac when blipping the throttle with 40mm Webers.

You should have 0 vac at idle. If you don't your carbs are not set up right. The vacuum will be right off idle. Most SVDA distributors will start advancing at roughly 3.25in and stop at roughly 8-10in

Pull the vac from only (1 vac port) off the carb (Dual Webers) not two. Doing so will lower the overall vac due to vac signal fighting each other. Install an anti pulse valve as close to the carb port as possible. This will not only smooth the signal but also increase it a bit. Preferably pull from #4 since it's closest to the distributor.

Anti pulse valve:https://vwparts.aircooled.net/Anti-Pulse-Valve-for-Vacuum-Advance-Distributors-p/anti-pulse-valve.htm

Vacuum advance is miles ahead of mechanical only.

Only then can one begin to lean tune the AFR during cruise.

WOT - 12:3 - 13:2
Part throttle - 16:0 - 17:0

Avoid - 14:0 - 15:0 (Deathzone) Highest EGT & CHT's Get above it when on the progression circuit and below it when on the mains.

Load = Throttle position

Part throttle is NOT load. To many folks believe holes in pistons are cause solely by a lean AFR. It isn't. It requires a lean AFR with timing issue (excess usually) combined with LOAD. If ones timing is spot on with an SVDA any load (foot in throttle) will pull the timing back (increasing load) to where it is set at full mechanical. Preferably no more than 28-32*BTDC @3200+rpm's
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