Jetting Recommendations?

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Wed Nov 14, 2007 9:59 pm

Hi, all. I've recently upgraded to a 32/36 DFAV carb, and I need some help getting it to run right.

Currently, the car is really fast in the higher rpm, but won't idle. I've followed the instructions I find on the weber sites for the "best lean/idle" setting, but I can't even get it to idle for long enough to do that setting.

When I got the carb, it idled but seemed offer no improvement in performance. After weeks of driving (14 miles every day on the freeway) and spraying the linkages with WD-40, it no longer idles, but is really fast in the upper rpm range.

I'm currently running 137/140 jets (idle/secondary). I can't read the numbers on the air corrector jets, but it looks like they both end in 20, like 120, 220, 720... i don't know what range the air jets run.

Do you all think I should go up or down on the jets? Does anyone else running this carb know what jets they've got? My engine is an unmodified 115k 1800 with stock exhaust and 1981 electronic ignition.

So Cal Mark · Post by **So Cal Mark** » Wed Nov 14, 2007 10:24 pm

upper rpm range is where you will see a perf gain since the primary bore is 32mm just like your stock carb. Air correctors are typically 170 to 190, so it sounds like yours has 220s. That may be way too lean on the primary side. Can you back the idle jet out slightly to see if that allows the engine to idle?

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 16, 2007 12:46 am

ou mean back out the air jet, like unseat it a little? I'll try it tomorrow AM.

So Cal Mark · Post by **So Cal Mark** » Fri Nov 16, 2007 1:25 am

not the air jet, the idle/low speed jet. With the engine idling, just slightly unseat the jet and see if the rpm picks up

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 16, 2007 10:04 am

I guess I'm confused. The only jets on the carb that are exposed when it's assembled are the air jets. I should open the carb, unscrew the jet inside the fuel reservoir, then reassemble and see if it runs?

So Cal Mark · Post by **So Cal Mark** » Fri Nov 16, 2007 10:32 am

the idle/low speed jet screws into the side of the carb that faces the left fender. On your stock carb it's on the end of the idle cutoff solenoid. The engine runs off that jet up to about 3500 rpm

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 16, 2007 10:41 am

ok. I get it. It's the large flat brass one... I'll try that. Thanks for your help. I really appreciate it.

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 16, 2007 11:19 am

Okay, after a brief lesson in the correct names of each carb jet, my idle jet is 47 with a 170 air jet and a 137 fuel metering jet. My secondary jet is 50 with a 170 air jet and 140 fuel metering jet.

The idle/secondary jets on my old carb (stock 32/32 adfa?) are 50/60. Since those barrels match the primary barrel on my 32/36 DFAV, I'm going to try the size 50 idle jet in place of the 47.

HOLLYWOODSPIDER · Post by **HOLLYWOODSPIDER** » Fri Nov 16, 2007 12:12 pm

The larger idle jet seems to have done the trick. I moved up to 50/60 on the idle/secondary jets. Purrs like a kitten, roars like a tiger. Thanks, Mark.

So Cal Mark · Post by **So Cal Mark** » Fri Nov 16, 2007 3:25 pm

cool, got the car running and learned something too!