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

[Beach_Bum]

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 Haven't had a chance to check yet, but will and report back

-coil in good condish? It's the coil that came with the car and is an unknown brand. There's a picture in post #15 of this thread

-fuel filter new? Yes, the universal fuel filter was purchased new and installed with the carbs

-can you hook up your fuel pressure gauge to see if you are getting enough pressure at those rpms?  I had the gauge hooked up when I first installed the regulator, and when I revved it up it stayed steady at 2.5 psi. What about volume at that range - I wonder if you are getting enough or too much to match engine needs at higher rpms? Is there a way to check volume?

-wires, cap and rotor in good condish? Wires are new Karlyn/STI, cap is brand new Bosch, rotor is from old dizzy, about 4k miles on it

-gas tank sender screen clean? Haven't checked

-plug gap in spec? I don't remember gapping the plugs when I first bought them, so they're probably at the factory gap

 

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.

 

Thanks Steve. I've answered your questions in red above.

 

As to your last point, I was reading back through some of my old notes before I messed with my float levels and didn't see anything about surging. It's been so long now that I don't remember if it was happening or not from memory. I've been doing some reading this morning on float levels, and it seems there are two different recommended "wet heights" which are measured from the machined surface under the jet inspection cover down to the top of the fuel. One recommendation is for 29mm and the other is for 25mm. Mine are set to 29mm.

 

Your last statement has me wondering if my popping at 2500 is because my float level is too low at 29mm and therefor, I'm running out of gas.

 

Another thing I'll throw in the mix that I've noticed is that when I remove the jet inspection cover, the top paper gaskets appear to be wet. I've also noticed more puddles of fuel in the upper left opening on the front face of the carb (forgot the technical name). But wouldn't this suggest there's TOO MUCH fuel?

Edited April 7, 2015 by Beach_Bum

[Stevenola]

Replace your mystery coil.  Do you run a ballast resistor or what is your setup?

Gap your plugs to stock, for 02's is it .028?

Rotor correct for your cap?  I usually buy these in pairs, what do the experts here say about old rotor/new cap?

Floats to 25mm.

Wet gaskets not unusual, this is why rubber is way to go.  The float vent puddling we'll ignore for now :-)

Report back on advance functioning.

 

We'll assume fuel volume ok for now.

[downhillwolf]

Gasket of inspection cover is wet if there is gas inside carbs(fumes...).
My money goes on cold start mechanism and not sealing pistons for cold start mixture. If sturging appers at that AFR number there should be at least one cold start mechanism that is not sealing and therefor one piston is rich and happy and another has too low fuel due to another rich mixture(higher rpm bacause of leaking cold start).
I did try on mine to seal them with silicone rubber but did not work. So i did just cold weld them, problem gone...

Any ideas from other guys how to make pistons seal or close them just to make sure that this might be issue...?

[Beach_Bum]

Replace your mystery coil.  Do you run a ballast resistor or what is your setup? Yes, pic below. What coil would you suggest?

Gap your plugs to stock, for 02's is it .028? I'll look in my manual when I get home. Looks like they come from NGK at .025

Rotor correct for your cap? I believe so. From what I read, my 008 and 002 distributors run the same rotors I usually buy these in pairs, what do the experts here say about old rotor/new cap?

Floats to 25mm. Will do

Wet gaskets not unusual, this is why rubber is way to go.  The float vent puddling we'll ignore for now :-) Rubber gaskets on the way from Pierce

Report back on advance functioning. Will do

 

We'll assume fuel volume ok for now.

 

[Stevenola]

Good point, we haven't ruled out them leaking either.  Instead of the blanking plates I have the original lever mechanisms wired together as if a choke cable is used but have the wire secured by set screws so they are locked in place.

 

On a previous set of DCOE's I threaded the cold start tubes leading into the venturi then blocked them with 6mm set screws.  That removed any possibility of them leaking.

 

 

Gasket of inspection cover is wet if there is gas inside carbs(fumes...).
My money goes on cold start mechanism and not sealing pistons for cold start mixture. If sturging appers at that AFR number there should be at least one cold start mechanism that is not sealing and therefor one piston is rich and happy and another has too low fuel due to another rich mixture(higher rpm bacause of leaking cold start).
I did try on mine to seal them with silicone rubber but did not work. So i did just cold weld them, problem gone...

Any ideas from other guys how to make pistons seal or close them just to make sure that this might be issue...?

Edited April 7, 2015 by Stevenola

[Stevenola]

I m sure there is plenty of debate about coils here from the members.  Usually it's a stock Black with ballast, Bosch Blue with no ballast (it's internally resisted) or a Bosch red with a 1.8 ohm ballast which is what i use.

 

You're convinced your cold starts arent leaking anymore?

[downhillwolf]

If coil would be bad then idle would be really shaky. Also at higher revs engine would behave paranormal. Like something is really wrong with engine.
 

[Beach_Bum]

I m sure there is plenty of debate about coils here from the members.  Usually it's a stock Black with ballast, Bosch Blue with no ballast (it's internally resisted) or a Bosch red with a 1.8 ohm ballast which is what i use.

 

You're convinced your cold starts arent leaking anymore?

 

At this point, I'm not convinced about anything on these carbs I will check them again to see if one (or more) is stuck open. I can't use the mechanisms because it interferes with my manifold, but if I find that they are still stuck open, I'll have to figure out a way to keep them closed. Maybe by threading them as you did.

[downhillwolf]

Beach bun, cold start could be leaky with pistons at place. Depends on the pistons seat and pistons have perfect shape to seal. There could be minimal space between them and they could still leak.
Cold start has a 6mm hole if i remember right, and vacuum is a force that depends on the area exposed. Only other way is to stuck holes where pistons should be with coned rubber to seal that 5-6mm hole... And make sure not to suck it through.

[Beach_Bum]

Beach bun, cold start could be leaky with pistons at place. Depends on the pistons seat and pistons have perfect shape to seal. There could be minimal space between them and they could still leak.

Cold start has a 6mm hole if i remember right, and vacuum is a force that depends on the area exposed. Only other way is to stuck holes where pistons should be with coned rubber to seal that 5-6mm hole... And make sure not to suck it through.

 

Oh, I didn't realize they could still leak if they're down. Thanks for the explanation.

[Stevenola]

Based on how your idle jets need to be further out than normal, this suggests compensating for leaking air not fuel.  However you can test the pistons by taking the covers off and while idling take a small screwdriver and lift up each piston, the engine should bog down then when relased the piston should snap into place from the force of the spring and then idle should come back to normal.  You can also see if they act up at higher revs.  Also spray some starter spray or whatever you use to test leaks by the pistons and see if there is a big leak somewhere.

[Beach_Bum]

New rubber gaskets should be here tomorrow or Thursday, so I'll check everything once they arrive and report back.

[Beach_Bum]

Goodies from Pierce haven't showed up yet, but I had a chance to plot my advance tonight. I had backed it off some last Sunday, but never got a chance to drive it because it started pouring rain. So here's where I'm currently at:

Idle 1000 rpm: 10*

1500 rpm: 14*

2000 rpm: 20*

2500 rpm: 22*

3000 rpm 29*

3500 rpm 33*

I hard a hard time getting it to stay steady at 3000 rpm. It was randomly popping and it kept revving up on me once I thought I had it set. Then when I backed it off a tad it would drop too far down. No trouble at the other rpms.

Also went for a drive and saw a bit of improvement in certain areas

55f9 idles

120 main

160 air

f16 em tubes

Idle screws 4 turns out

Idle: 12.5-13.5

2500 cruise (4th gear): 12.5-14 random surging/popping

2500 cruise (3rd gear): 13.5-14 lots of popping/surging

3000 cruise (4th gear): 12.5-13.5 no surging

3500 cruise (3rd gear): 11-11.5 light surge

Normal acceleration: 12-13

WOT: 11-12

Couple things I noticed while driving. As you can see, the surging and popping at 2500 is much worse in lower gears, and it happens only randomly in a higher gear (about 10-15% of the time). Light throttle take-offs, such as pulling out of my driveway or a parking space makes for lots of popping from the carbs. Lastly, the numbers from my WB02 were much more precise, meaning that instead of jumping in 1 to 2 point increments, they were mostly staying within 1 point of each other. Could this be because of the timing change?

I cracked the tops off the carbbs to peek at the cold start valves before I started it up and both springs on the right carb shot up at me, while the ones on the left carb remained in place. I put them back in their place with the retainers on top. Starting the car tonight was more difficult than normal, taking about 4-5 cranks and a couple pedal mashes between each crank. Also lots of popping when it finally did start.

I mention all of this because I'm thinking more and more that the cold start valves might be the culprit. From the trouble I had getting a steady idle at 3000 rpm, to the random popping at 2500 cruise (after it popped things seemed to stay steady for a while), to the popping when pulling out of the driveway, and, like Steve said the excessive turns out on my mixture screws. This is all my uneducated theory, so please correct if I'm wrong.

So, I guess the question is...is there a non-permanent fix I can try? Maybe a heavier spring to keep them held down? Maybe a dowel on top of the valve to keep it down?

Edit: Or I guess it could also be fuel level since I haven't changed that yet. Maybe low fuel isn't allowing the transition to mains soon enough? Or it's starving for fuel at lower rpms?

Edited April 9, 2015 by Beach_Bum

[Stevenola]

Sorry I wasn't clear, I meant take the covers off the cold start valves off (the blanking plates) not the tops of the carbs.  With the blanking plates off the exposed cylinder can be raised and lowered with a screw driver.  ALso with the blanking covers off you can spray some stuff on the exposed piston to see if you get a change.

 

Make sure the spring retainers are tight and that they hold the spring and piston in securely - they shouldn't pop out like that.  I think the spring retaining clips can be bent to provide a tighter fit.

 

Your popping seems to be worst at light loads and off idle.  Something is preventing your idle jets from doing their job.  Like an air leak somewhere.  Once your mains come in, your afr's are predictable.

[Beach_Bum]

I understood you Steve, just didn't have time to take the blanking plates off last night because it requires me to remove the fuel pump. I'll take them off and check it out tonight or tomorrow.