engine and drivetrain Need Help! Weber DCOEs Running Rich on Mains. Can't Lean Them Out

[Beach_Bum]

Thanks Steve. What would you suggest for initial timing with the vac advance distributor?

My Korman manifold has a plugged port on the bottom of it. I believe it's a 5/16-24 size so I'll look for something that I can plug into it and run the vacuum line to that.

[Beach_Bum]

I have a brand new Ireland unit I can send you.

Ed

Hey Ed. I was thinking the surging at cruise speeds might happen because there is no vac advance on my current setup. Is this incorrect?

[Guest_anonymous]

best not to run the vac advance through manifold at all. just run the dizzy to see if that is the issue of the surging. don't try to tune your carbs with that dizzy. Is your 008 a vacuum retard unit from the '74 tii? just set it to a base timing at the ball 1500-1600 rpm  or go further up to 30-34 at 3500rpm. this is just a test, only a test.

[Beach_Bum]

best not to run the vac advance through manifold at all. just run the dizzy to see if that is the issue of the surging. don't try to tune your carbs with that dizzy. Is your 008 a vacuum retard unit from the '74 tii? just set it to a base timing at the ball 1500-1600 rpm  or go further up to 30-34 at 3500rpm. this is just a test, only a test.

It's a 0 231 180 008 distributor that came with my 7/72 standard 2002.

[Guest_anonymous]

in any event advance or retard, the vacuum pot gets connected to a ported vacuum, not manifold vacuum. Manifold vacuum will be triggering the vac pot all the time, you want the vacuum pot triggered with the acceleration transition. I see your base timing was 30* degrees at 2000rpm, is this the spec for the 002 dizzy? the stock centrifugal only timing was the ball at 2400rpm.  where are you at 3500rpm? 

you can also hunt down a shop with a distributor machine and have your advance plotted and verified

Edited April 6, 2015 by dar_on_

[Beach_Bum]

in any event advance or retard, the vacuum pot gets connected to a ported vacuum, not manifold vacuum. Manifold vacuum will be triggering the vac pot all the time, you want the vacuum pot triggered with the acceleration transition. I see your base timing was 30* degrees at 2000rpm, is this the spec for the 002 dizzy? the stock centrifugal only timing was the ball at 2400rpm.  where are you at 3500rpm? 

you can also hunt down a shop with a distributor machine and have your advance plotted and verified

Makes sense, thanks for explaining.

Timing at 30 degrees at 2,000 was on the recommendation of a forum member. I must admit, I never checked where I am at 3500.

[Guest_anonymous]

might as well throw this out there

Ignition timing.pdf

Ignition timing.pdf

[Stevenola]

I use manifold vacuum for timing.  Ported vacuum came into vogue for emissions reasons and a quick stop gap to get cars to pass inspection.  Before emissions laws, cars used manifold vacuum.  The benefits are lower idle temps and advance dropping out when engine load increases.  When the accelerator pedal is pushed hard you want less vacuum advance because a rich slug of fuel does not need to be lit early.  Low load lean fuel mixtures, such as at idle or cruise, need extra advance.  Ported vacuum does the opposite.  In any event, for testing your mixtures I would disable all vacuum advance to get a baseline.

 

I suggest not using any ported vacuum for advance.

Edited April 6, 2015 by Stevenola

[Rustpile]

OK, here you go

Norwegian car, Tønsberg registered? Who owns it?

[Beach_Bum]

might as well throw this out there

 

So, if I'm looking at this correctly (and I may not be due to lack of coffee)

 

a standard 2002 @2000 rpm should be between 31-36 degrees and all in at 38-42 degrees by 2700 rpm

a 2002ti @2000 rpm should be between 20-32 degrees (depending on distributor model) and all in at 32-37 degrees by 3500 rpm

a 2002tii @ 2000 rpm should be between 15-20 degrees (USA model distributor) and all in at 27-32 degrees (USA model) by 3500 rpm

[Stevenola]

Looks like with your 0 231 180 008 spec is all in by 2400 rpm and max advance is 32.  No vacuum for setting the timing.  This will get you in the ball park.   The curve graphs are measured at the cam which is half crank speed so you have to double it.

[zinz]

Without triple-checking things, that sounds about right on dizzy specifications.  You can easily adjust your ignition timing a bit to see if less advance solves your surging-at-cruise. I'm the one who advised more advance, but perhaps your set-up won't tolerate that much advance?  Every engine behaves differently... I only settled on that 33@2000 #  with my mechanical advance-only dizzy after a good bit of trial and error.

 

I'll see if I have a decent vac-advance distributer in my parts stash... it may not be any better than what you already have, though.  I'm happy to send you the new Ireland unit to try out if you'd like...at least it's new.

 

I ran an Ireland dizzy an didn't have any surging issues at cruise...at least nothing intolerable, that I can remember.  The new 123 with vacuum is certainly much smoother across the board.

 

The other step you could take with your dizzy is to map the curve with your programmable timing light. That way, you KNOW what you have. 

 

It's easy, thanks to Daron  http://www.bmw2002faq.com/topic/155102-plotting-vacuum-advance-distributor-curves/

 

Ed

[Beach_Bum]

I think I'll play with the advance on my current distributor since it's already in the car and see where that gets me. If nowhere, then I'll switch to the vac advance and see what happens.

 

Thanks everyone. I'll update once I've had a chance to fiddle with it.

[Stevenola]

+1 on mapping your curve with an advance timing light.  That way you know if you're not getting enough or too much advance where you're supposed to.

[Stevenola]

The surging is puzzling.  At those afr's in the 11-13 range there should be no issues.  Things to check there for your 2500+ rpms:

 

-timing - are you in spec at all rpms?  I don't think a few degrees off is going to affect your afr's very much but you need to verify mech advance works

-coil in good condish?

-fuel filter new?

-can you hook up your fuel pressure gauge to see if you are getting enough pressure at those rpms?  What about volume at that range - I wonder if you are getting enough or too much to match engine needs at higher rpms?

-wires, cap and rotor in good condish?

-gas tank sender screen clean?

-plug gap in spec?

 

Have to eliminate all these possibilitie before we blame the carbs, but the jet size and lack of good progression is a concern.

 

Your wot numbers reflect the larger main jet size so they seem to be coming on ok.

 

Somewhere I have some info on recommended jetting for 2002 so I will check and see. 

 

At 2500+ cruise it appears you are still on idle jets and popping means you're running out of gas.  I will be back with some more idle/main suggestions.  If your distrib is working and you are close to spec I don't think timing is going to solve this.

 

First test: 115 main 160 air 55f9 idles f16 tubes

Idle screws 4 turns out
Idle: 12.5-13
2500 cruise: 14.5-16 surging and popping
3000 cruise: 13.5-14 surging and popping
3500 cruise: 11.5-12.5
Normal acceleration: 12.5-13.5
WOT: 12.5-13.5

Second test: 115 main 160 air 55f9 idles f16 tubes

Idle screws 3-1/2 turns out
Idle: 14.5-16
2500 cruise: 14.5-16 surging and popping
3000 cruise: 12.5-13 light surging
3500 cruise: 11-12 surging
Normal acceleration: 12.5-13
WOT: 12.5-13.5

Third test: 120 main 160 air 55f9 idles f16 tubes

Idle screws 3-1/2 turns out
Idle: 14.5-16
2500 cruise: 14.5-16 surging and popping
3000 cruise: 13.5-15 surging and popping
3500 cruise: 11-12
Normal acceleration: 12.5-13
WOT: 11-12

Fourth test: 120main 160 air 65f8 idles f16 tubes

Idle screws 3 turns out
Idle: 13.5-15
2500 cruise: 11.5-12 surging
3000 cruise: 9.5 surging
3500 cruise: 9.5 heavy surging
Normal acceleration: 10-11
WOT: 9-11

The bolded portions are what I changed on each test. What I've concluded from all of this is that my car does not like light throttle cruising. It seems that no matter the AFR there is surging and/or popping.

I can defintely live with some of theses numbers (like from test 1), but I can not live with the surging at cruising speeds since this is where a good majority of driving is spent.