Attn: Jeano

[Darren]

Your inbox is full so I could not reply to your P.M.

So here it is ...

Hi Jean, the combination looks to be fine, It should be an easy combination to dial in unless something is seriously wrong with a specific component like carbs or ignition....

 I do have a few questions

Other than the huge flat spot, does it run fine ( runing on all 4 cylinders and not misfiring?)
How does it Idle ? Rough , Smooth?
Are these New Weber carbs or used? ( real ones or chinese copies ) ?
Do each of the air fuel adjustment screws respond to adjustment on the carbs ?
What is your current jetting? Idle Jet, Main Jet , and Air corrector, also what number Emulsion tube?
Heads, What wersion of CB big valve heads are they and how big are the valves? ported or not?
What is the compression of the motor?
What rocker arms are on the motor?
What pertronix distributor do you have?
What exhaust system is on the motor?
Do you have a wide band air fuel ratio guage connected for tuning?

Thanks

Darren

[jeano]

Thanks for the reply, I've emptied my box and only now seen your reply
The engine runs fine at higher revs, but bogs down badly down low
The Webers are new (Spanish ) from CB, were on big beef manifolds, now on regular manifolds
I changed the jetting to that recommended by CB for dual 44s
Main 1.55  Idle 0.6 Emulsion F11  Air correct 2.00 Venturis 32
The idle mixture screws do all respond, and I'm using a snail to balance them
The heads  are 044 ultra mag plus 44x37.5
Pertronix 009 style , I've tried from 10 btdc to tdc with no real difference
Rockers are Scat 1:4 forged
Exhaust is 15/8 merged header with Mondo muffler
I gave up trying to get my LM2 to work, and hooked up a wide-band gauge tonight- it seems to consistently run at 9.5 to 10, so very rich?- I was surprised as it still often pops and bangs while idling and on over-run
One thing I haven't been able to check is fuel pressure, I' m using a low-pressure electric pump
Thanks for reading all this, I probably should have answered by PM

[Darren]

Hi, replying here is OK then others who read it can also learn.

Yes its way too rich,  your Idle air fuel ratio should be up in the  13:1 -14:1 ratio. ( but this is not written in stone, the motor will tell you what it is happiest with )

your air fuel flow guage is only for synchronizing the left and right carbs for air flow ( not for adjusting air fuel ratio )

My first steps would be to read these 3 articles.

http://www.aircooled.net/how-to-set-up-vw-carburetors/
http://www.aircooled.net/synchronize-dual-vw-carburetors-103/
http://www.aircooled.net/vw-carburetors-jetting-102/

Put in a 55 Idle jet
Put in a 135 Main Jet
Confirm fuel pressure is no higher than 3-3.5 PSI
Set total timing at 3500 RPM to 30 Degrees ( total advance timing set with motor reving to about 3500 RPM )   dont worry what the idle timing is at this point.
Next balance left / Right carb air flow  with your snail, and try to get it idling at 8-900 RPM or lower if possible
( then put the snail away )
After engine has warmed up Perform lean best Idle adjustment on all 4 cylinders, This means pick 1 cylinder, slowly turn the idle mixture screw inwards untill that cylinder drops out, then back the screw out slowly until that cylinder picks up, after you find the point that the cylinder is firing again go exactly 1/2 turn out further on that adjustment screw,
Move to the next cylinder and so on.
After you have done all 4 and you find you are now idling either too high or too low, readjust the throttle stops on the left and right carbs again using the snail meter to get you the idle RPM you want..
Then perform the lean best idle adjustment again as decribed above,
Any time you change, timing, Throttle position, or idle jet you need to perform the lean best idle mixture screw adjustment.

There is another really long thread of over 45 pages of information on the Samba that I have told  people to read and its worth reading through.  You have to sift through spme B.S. but pay attention to what John Connely says in his replies.
 
http://www.thesamba.com/vw/forum/viewtopic.php?t=293837

Good luck and keep us up to date on how you progress.  Your motor looks to be a good combination and you should be able to get it running well.


Cheers Darren

[jeano]

Thanks
These are the procedures I've done many times over, hopefully the jets will make the difference and I'll check the fuel pressure
I've ordered the jets, will let you know!
Again, thanks
Jean

[rekka]

Forgive me for jumping into this thread, but I have two of my adjustment screws not responding like you mentioned above. What could be the cause of that. I have stripped and cleaned my HPMX's three times as I thought i had some crap in there.

[Darren]

Forgive me for jumping into this thread, but I have two of my adjustment screws not responding like you mentioned above. What could be the cause of that. I have stripped and cleaned my HPMX's three times as I thought i had some crap in there.

are both screws on the same carb?
Check the plugs to make sure they are not fowled first
Check to see if fuel is dribbling on the the throttle plate during idle,
Float height 10.5mm
Check fuel pressure no more than 3.5 ( less is better )
Vacuum leaks?
If you cant find anything I would swap carbs side for side and see if the symptom follows.

Cheers

[rekka]

Yes they are on the same carb. Plugs are all perfect, stock fuel pump, pressure unknown. I won't have a chance to check anything else till I get home from the show this weekend as we are driving it down tomorrow, but it runs great on the main circuit. I haven't measured float height, but when I cleaned the carbs, both floats were the same level. Thanks for the tips, if you are around this weekend, I'll buy you a beer.

[rekka]

The bus made it there and back from the Okanagan with no issues. Plus it ran 18.3's on the strip. Since I've been home I've checked the floats and they were both out, exactly as you predicted, the "unadjustable" side being only 5mm closed. They are now fixed and I am down to one barrel that doesn't respond. #1 cylinder. Already idling much nicer with no more popping.

[rekka]

Eureka, a giant vacuum leak. A piece of my manifold to head gasket had somehow broken away and got sucked through the motor on #1 cylinder. Made a new gasket last night and running like a trooper again. Thanks again Darren.

[jeano]

OK, here's where i'm at :

it's almost driveable, def a big improvement!
i've instrumented the motor with WB AFR, tach and FP regulator and gauge, set to 2 psi
Timing 30 degr at 3000 rpm
Floats at 10mm
I put in 50 idle jets, and the 135 mains (both came with the carbs)

It idles at 13-14 AFR, still goes up when I open the throttle, but much crisper now. Above 2500-3000 rpm it still shows about 10-10.5 on the AFR gauge

I've ordered 45 idles, and think I may need to try 125 mains?

Two questions- we are at 2500 ft, would that be enough to need smaller jets? And does the lean best idle setting affect only the idle, or the whole rpm range up to 2500?

Thanks for the help
Jean

[Darren]

Hi The 50 idle jet seems about right,  You definately need a smaller main jet.  125 main is a good guess   ;o)

[jeano]

Thanks, I've got them on order, will report back
Jean

[Darren]

Forgot to ansewr your question...

lean best Idle adjustment only adjusts the Idle mixture, as soon as you step on the gas pedal even a tiny bit, you are now on the Idle jet and the lean best Idle mixture setting no longer comes into play.

The other think that will effect the intital mixture when you step on the gas is the acceleration pump adjustment.