Weber 32/36 jet questions

[shanon]

Howdy Coupers,

Have determined that my Weber 32/36 downdrafts should be rebuilt after a couple of shakedown runs, car is running very rich and backfires/hiccups when stomped on.....so I'm 'going in'.

I have successfully done one before and have been told I should do the rebuild prior to having a professional tune and/or dyno session for best results from sessions. Makes sense.

Can anyone tell me what the proper jets should be for a 2.8L so I can verify proper set-up or make some corrections. I am basically at sea level if altitude matters.

Even the short shakedown runs bring HUGE smiles to my face..

Keep Coupin' and TIA
-shanon
'70 2800cs

 

[decoupe]

Attached is the stock jetting chart for all current weber carbs. Probably a good starting point for sea level.

http://www.racetep.com/webercarbjet.html

Also worth looking at is the idle circut using the weber best lean idle link below fpr Progressive Carbs.

http://www.racetep.com/webtechframe.html

 

[Ed Giguere]

My car would not keep a constant speed and would bog and surge while holding pedal steady until I changed my primary jets to 145's (Correction, actually 140's)

I have very nice throttle response now and it will cruise well at any speed. Lost a little in MPG but it is well worth it. I am at sea level in CA and have the 32\36's with K&N's on a stock 3.0.

 

[Arde]

Ed, that is interesting.

How did you diagnose the cause and determine the fix?

 

[Ed Giguere]

Great classic BMW mech in Sacto, Porsche too!

"Schatz and Krum Independent BMW" in Sacto properly diagnosed this for me. Stuart Krum there has always taken great care of my cars since 1985, and I had brought my coupe to him for some suspension repairs one time. He drove it around and asked me if I wanted him to clear up the surges with the carbs when trying to cruise at a constant speed while he was at it, he said he was sure it was just incorrect jets in the webers and an hour or two on the dyno and he would have it corrected. I replied with an enthusiastic "YOU CAN FIX THAT?" An hour and a half later, and voila! My car now cruises smoothly at a constant speed whan asked. It just purrs......

I just pulled out my old work order, here is what he wrote down.

"AFR was 15.1 cruising with 125 mains, rejet with 140's and now AFR is 14.5."

So I guess the were 140's and not 145's, damn memory!
Cost me $7.50 for two jets and the 1 1/2 hours of labor. DEAL!!!

Schatz and Krum 916-381-5321

Nice day here today, think I will take the coupe out to the coast. :lol:

Cheers,
Ed

 

[Arde]

Thanks Ed. I'll do the followup based on your experience.