123ignition distributor install
- Thread starter Stevehose
- Start date
This is the type of thread that would be put in a "Blog" when we change over to a content management system (CMS). The "How To's" if you will. Great info..
Dan
Dan
DerSchwede
Well-Known Member
Excellent info and highly interesting reading Steve!
maybe I'll try that route with my tripples if I get tired of fiddling with those small dizzy springs... ;-)
Cheers
A
maybe I'll try that route with my tripples if I get tired of fiddling with those small dizzy springs... ;-)
Cheers
A
TodB
Well-Known Member
Maybe I missed it, but triples aside, what are the specifics of your motor, i.e. displacement, compression, cam, other mods.
This has been a great thread, BTW.
This has been a great thread, BTW.
Points v. Pertronix v. 123ignition
Interesting comparison between the 3 options:
https://www.youtube.com/watch?v=9XcqgLdeRGg
Interesting comparison between the 3 options:
https://www.youtube.com/watch?v=9XcqgLdeRGg
This morning I experimented with the vacuum advance and the "gear shift retard" theory. With my previous advance curve, it woud add 8 degrees at any vacuum over 6hg or so. This is good for idle and cruising, but in between shifts, the vacuum jumps higher than the idle or cruise levels so it signals the distributor to add advance. So if you're on the throttle and you let up on the pedal between shifts, the advance is too high when you slam back on the gas, it has to sense the dropping vacuum and adjust accordingly and therefore there is a short lag period. By setting the curve to drop out past a certain vacuum level, the timing does not change with very high vacuum, it stays where it is supposed to be with centrifugal/rpm. As a result the timing is right where it should be when going into next gear. The result is a crisper shift. Here is the curve I am using now:
Compared to the previous curves, you can see the addition of advance between the desired vacuum levels, keeping cruise and idle advance in tact within the bell curve, and dropping out under load (on the right) and in between shifts (on the left). The vacuum levels to determine these points are read off the dashboard display's vacuum gauge under various driving conditions.
The engine now pulls stronger into the next gear.
Compared to the previous curves, you can see the addition of advance between the desired vacuum levels, keeping cruise and idle advance in tact within the bell curve, and dropping out under load (on the right) and in between shifts (on the left). The vacuum levels to determine these points are read off the dashboard display's vacuum gauge under various driving conditions.
The engine now pulls stronger into the next gear.
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TodB
Well-Known Member
OK, now you are having way too much fun!
Yeah, my friend took it for a test drive today and caught rubber in 2nd and 3rd gear. I wouldn't have driven it that hard but it is running pretty well rignt now.
I have a dyno appointment in mid June for the final curve plotting.
I have a dyno appointment in mid June for the final curve plotting.
TodB
Well-Known Member
Not that you need more, but are you limited to 5 points for the ignition curve?
too much!
It was the UK Jag guys that first turned me on to this NL company some years ago. As proud as I am of running an authentic xk 3.4liter including breaker points ... this whole thread has just about pushed me over the edge for trying a 123 in the old cat.
What would be cool if you could do a dyno run with your old distributor so we could get a sense of the improvement from the 123
It was the UK Jag guys that first turned me on to this NL company some years ago. As proud as I am of running an authentic xk 3.4liter including breaker points ... this whole thread has just about pushed me over the edge for trying a 123 in the old cat.
What would be cool if you could do a dyno run with your old distributor so we could get a sense of the improvement from the 123
That's a good idea but I am not certain my old distributor would be worth basing a test on or dropping more dyno dollars on. I'd guess most original distributors in old cars are not running optimally by now and could stand some attention.
Regardless, my engine runs better and because the curve is infinitely adjustable, that's good enough for me even without the dyno. But hopefully I will find a good curve on the machine then set it and forget it.
Regardless, my engine runs better and because the curve is infinitely adjustable, that's good enough for me even without the dyno. But hopefully I will find a good curve on the machine then set it and forget it.
I wouldn't pay extra either
I wouldn't pay more to test the old distr either. The one on my Jag has plenty of dwell jitter and ought to be rebuilt ($300). I'll hate losing the visual originality, but I'll love the better performance when I retire the 60 year old original diz.
I wouldn't pay more to test the old distr either. The one on my Jag has plenty of dwell jitter and ought to be rebuilt ($300). I'll hate losing the visual originality, but I'll love the better performance when I retire the 60 year old original diz.
Latest curve
Loaded this one, I started the vac advance at 0 rpm instead of 400, this would prevent any delay in it kicking in.
I made the advance curve linear, taking out the higher slope early on, this seems to have eliminated a slight hesitation when starting off from a stop.
I made the drop off of advance quicker and earlier when the vacuum drops on throttle loading. This appears to have helped off-cruise acceleration.
Also I was off 2 degrees on what the 123 said and what my strobe measured for timing so I re-adjusted the distributor to sync them.
Will give it a thorough testing this weekend.
Loaded this one, I started the vac advance at 0 rpm instead of 400, this would prevent any delay in it kicking in.
I made the advance curve linear, taking out the higher slope early on, this seems to have eliminated a slight hesitation when starting off from a stop.
I made the drop off of advance quicker and earlier when the vacuum drops on throttle loading. This appears to have helped off-cruise acceleration.
Also I was off 2 degrees on what the 123 said and what my strobe measured for timing so I re-adjusted the distributor to sync them.
Will give it a thorough testing this weekend.
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Curve du jour
Today I focused on dialing in the cruise behaviour, the previous advance curve was dropping out too quickly on the highway under subtle throttle changes (like when a dip or bump would transfer some force through the pedal against my foot and change the throttle slightly).
So I added some slope in order to smooth out the sensitivity on the highway, it still drops out quickly if I accelerate but at 70-80mph cruise I am getting a consistent 8-10 more degrees from the vacuum advance for some (theoretical) fuel economy. Max vacuum advance is now 10 instead of 8 because:
I also dropped the all in mechanical to 30, this is what produced the flattest torque curve on my dyno runs last year so I wanted to experiment with that and will keep it here until it goes back on the machine next month. I want as much torque as possible for accelerating out of the Starbucks parking lot.
Today I focused on dialing in the cruise behaviour, the previous advance curve was dropping out too quickly on the highway under subtle throttle changes (like when a dip or bump would transfer some force through the pedal against my foot and change the throttle slightly).
So I added some slope in order to smooth out the sensitivity on the highway, it still drops out quickly if I accelerate but at 70-80mph cruise I am getting a consistent 8-10 more degrees from the vacuum advance for some (theoretical) fuel economy. Max vacuum advance is now 10 instead of 8 because:
I also dropped the all in mechanical to 30, this is what produced the flattest torque curve on my dyno runs last year so I wanted to experiment with that and will keep it here until it goes back on the machine next month. I want as much torque as possible for accelerating out of the Starbucks parking lot.
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Another vac source?
This sounds stupid but I'll ask anyway. Even if your DCOE manifold doesn't have a MAp port, it will have a vac takeoff for the brake booster. Because there's a one way valve on this line, could you tap off the engine side of the booster line as a MAP signal? I suppose the best this it to stick a vac gauge on it and see how much it bounces around.
This sounds stupid but I'll ask anyway. Even if your DCOE manifold doesn't have a MAp port, it will have a vac takeoff for the brake booster. Because there's a one way valve on this line, could you tap off the engine side of the booster line as a MAP signal? I suppose the best this it to stick a vac gauge on it and see how much it bounces around.
The brake booster port is on the #1 intake runner. My DCOM carbs have manifold vacuum ports on each barrel so I just use one of those (#6 close to the firewall), it's the same as tapping the booster port but not as noticeable. The Alfa anti pulse valve works well enough for the single port to signal the distributor accurately. The rest of the ports are capped. The rear carb also has a ported vacuum port that I don't use.
Booster port:
Manifold vac advance port (braided hose):
Booster port:
Manifold vac advance port (braided hose):
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manifold versus throttle plate vacuum port
Steve, from these 2 pictures, the booster is using manifold vac and it seems like you are using vac from just downstream of the throttle plate for your distributor. These are a little different in their characteristics (I think).
THanks for the pics.
Steve, from these 2 pictures, the booster is using manifold vac and it seems like you are using vac from just downstream of the throttle plate for your distributor. These are a little different in their characteristics (I think).
THanks for the pics.
I am using manifold vac for both booster and distributor. Here is s closeup of the rear carb which has the ported vacuum take off, it's the one that is capped off with the black plug (pointing away at 5 o'clock) and is separated from the manifold port (braided hose) by the throttle plate. Each carb has a manifold vac port on each barrel which I use for balancing.
#5 barrel vacuum port is located just to the right and below the idle mixture tower and is capped:
So the distributor can be used with either manifold or ported vacuum, I use manifold because I want the extra advance at idle and I don't want extra advance when accelerating. From my readings the auto industry switched to ported vacuum solely for emissions reasons and that manifold vac was always used prior to that. At cruise and WOT, manifold and ported vacuum are equal.
If you want manifold vacuum with DCOE you could just tap one of the intake runners, for example #6 so it is out of the way and get the anti pulse valve to help smooth out the signal. Also depends on which runner the booster tap is on, I've seen different tapped runners depending on intake manifold manufacturer and how it's installed. Personally I like booster vac off #1 port for ease of connection to the booster and #6 for the vac advance, this keeps the whole rig a little cleaner visually. Or like you say you could just tee into the booster source.
#5 barrel vacuum port is located just to the right and below the idle mixture tower and is capped:
So the distributor can be used with either manifold or ported vacuum, I use manifold because I want the extra advance at idle and I don't want extra advance when accelerating. From my readings the auto industry switched to ported vacuum solely for emissions reasons and that manifold vac was always used prior to that. At cruise and WOT, manifold and ported vacuum are equal.
If you want manifold vacuum with DCOE you could just tap one of the intake runners, for example #6 so it is out of the way and get the anti pulse valve to help smooth out the signal. Also depends on which runner the booster tap is on, I've seen different tapped runners depending on intake manifold manufacturer and how it's installed. Personally I like booster vac off #1 port for ease of connection to the booster and #6 for the vac advance, this keeps the whole rig a little cleaner visually. Or like you say you could just tee into the booster source.