1971 250 stalls when I put in drive

[Jub]

Recently bought 1971 Mercedes 250, replaced zenith carbs with webers, it idles fine but everytime I put it in drive it stalls (works fine in park and neutral)?

[socalbenz]

If the reverse band on the auto tranny is adjusted too tight it can cause the car to stall. Could be a million other things too.

[MEPEH]

I'm really bad at carbs, but i know there's an adjuster for that.
I know i had issues with my Zeniths and it was shifting hard. My mechanic adjusted the carbs and it shifted like silk. He mentioned there was a link out of adjust and that adjustment also can cause the car to stall when out of P or N

[bcbens@embarqma]

Originally Posted by Jub

Recently bought 1971 Mercedes 250, replaced zenith carbs with webers, it idles fine but everytime I put it in drive it stalls (works fine in park and neutral)?

Go to this site for Weber tuning and adjustments. It is critical that the carbs are correctly adjusted with all linkages on the carbs, to the throttle and to the transmission correct before you adjust mixture and idle. Make sure your dwell and idle RPM is correct as well.
Weber CARBURETOR SET UP AND LEAN BEST IDLE ADJUSTMENT

[Jub]

I used the "carb set up and lean best idle adjustment" instructions when I installed the weber, but it is still having problems.

I will most likely take it to a professional to have is synched correctly and adjusted...but I think it may be something different. I tinkered with adjustment screws/mixture screws for hours without any luck.

I also changed the fuel pump, and searced for any leaks in my vac tubing...nothing

Any other ideas (however far fetched) would be greatly appreciated (thanxs)

[bcbens@embarqma]

Originally Posted by Jub

I used the "carb set up and lean best idle adjustment" instructions when I installed the weber, but it is still having problems.

I will most likely take it to a professional to have is synched correctly and adjusted...but I think it may be something different. I tinkered with adjustment screws/mixture screws for hours without any luck.

I also changed the fuel pump, and searced for any leaks in my vac tubing...nothing

Any other ideas (however far fetched) would be greatly appreciated (thanxs)

Double check your dwell. Idle is the first thing that you will notice when your dwell is off. At least it's that way on mine. It gets real rough and wants to stall.
Pull the vacuum line off at the top rear of the intake manifold and plug it. That will eliminate all vacuum except intake manifold to block and carbs to intake. When you plug it give it a few seconds to stabilize before expecting improvement.
Make absolutely sure that the throttle rod is not holding the carbs open. Even being open a small amount more than carb set up recommends will give the carbs way too much gas and cause stalling.
I'm no expert, but these are problems that I have experienced with my webers in the past.
Good luck to you.

[Jub]

Charlie,

Will do, hopefully this may help.

Thnx

[JPMOSE]

I know on my 250SL there's an idle compensation solenoid that slightly increases the throttle when A/C and/or the automatic transmission is engaged into a reverse or forward gear. I would think the carb setup would have this as well, especially when the A/C compressor is engaged. Have you looked into this by chance?

[Jub]

JPMOSE,

Looked into that, but there is no solenoid on the 71 250 (when I read about this I ran down to look for it in my car few days ago but couldn't find it). I have since seen it on other benz's (250 SL) in wrecking yards. So this isn't it.

[dobrodan]

I believe your car should have a vacuum box attached to the front carb which raises the idle when the transmission is engaged at idle (vacuum increases). They sometimes are missing because "mechanics" who don't understand the carbs remove them and just raise the idle to compensate. You should also check your distributor to make sure that the centrifugal and vacuum advances are not sticking at all. That could drive you crazy trying to tune the car. Check the vacuum at the front carb and at the transmission too.

[Jub]

Problem solved: I used carburator cleaner (works like a charm) and found I had a leak where my webers meet the manifold (gasket)...up and running (thxs all)