Turn weber screw in or out on popping barrels?

EarlyPorsche · 11-06-2006, 08:52 PM

Ok tomorrow I plan on taking my air cleaners off, starting my porsche up cold and adjusting the barrels that pop when its cold out. I think if I just adjust them an 1/8 of a turn it would be a big difference. Any ideas? It pops when warm too but not as frequently or as bad. I figure if I adjust it cold at least I will know which are popping as it happens alot. Any ideas? Screw out right?

Steve@Rennsport · 11-06-2006, 09:15 PM

Right.

The popping is indicative of a lean condition so open the screws to admit more fuel.

Chuck Moreland · 11-07-2006, 08:37 AM

Steve's comment is right on.

If you haven't done this before, I would really suggest you learn to fully adjust the carbs - float levels, air screws, linkage etc. Do some searching on this board - there have been some excellent step-by-step descriptions. You need to perform the steps in the right sequence, and you need a couple specialized tools.

john walker's workshop · 11-07-2006, 08:56 AM

adjusting it cold won't do you any good. equal airflow through each barrel should be adjusted with a syncometer, before doing the mixture adjust. idle jet size should be checked with a jet gauge to be sure you don't still have .45 or .50 jets like they came with originally when gas was still good.

}{arlequin · }{arlequin's Garage

subscribed. if you get around to it can you please post pics of which screws you're messing w/ as well? thanks... (carb'd newbie)

304065 · 11-07-2006, 09:53 AM

"Most carburetor problems are the fault of the ignition system."

I would check the timing, dwell and advance curve and the plugs and wires before touching the carbs. You need a solid 900 rpm idle which you won't be able to get if there's too much advance.

Then check the float level and fuel pressure. You want about 3.5 psi and the float level exactly between the meniscus on the float gauge.

Then it's time for the synchrometer. Adjust the airflow with the engine at operating temperature, because when it gets hot the linkages change. Follow the procedure in CMA, average the airflow from the stacks and adjust to that value.

John Walker, what idle jet size do you recommend for a bone-stock, solex-carbed '66 with today's Reformulated Panther Pee that we call fuel?

EarlyPorsche · 11-07-2006, 10:07 AM

Timing is via electromotive distributorless system and is spot on. I started it stone cold, watched for pops/sparks. Loosened the screw on that barrel in little bits until it was gone. About 90% of my woes are gone now. The other 10% will be sured when I get the throttle shafts rebushed as they are a bit loose and can move. For anyone with the same problem just loosen the outer screws on the barrels with the sparks and you should be fine. Once warmed up it runs better too. Oh of course if you are doing this first install some new plugs and check timing like has been mentioned. I plan on doing the "perfect tune" with all the fancy procedures and tools once I get my carburators back from the rebuild shop.

lateapex911 · 11-07-2006, 10:11 AM

This thread could get long, LOL.

One thing to be aware of: If the throttle shafts are loose and leaking, it's a long road to carb happiness, and involves rebuilder,

John, I'm leaving for GA in a second, so i won't be able to thank you for a response to this: Where is a good CMA for carbs? (Webers) Thanks!

shbop · 11-07-2006, 11:04 AM

signing up

RoninLB · 11-07-2006, 11:37 AM

I don't get it?

I didn't know you could cold start Webers without chokes and prevent that lean condition.

I also never heard of cold adjusting the idle mix.

So far afaik... if your carbs & ignition are properly set on a good engine so called cold start richening to prevent initial popping will crash power output.

fwiw.. I was just cold starting my carbs in 24F a few days ago..
sure a little initial popping but no biggie. Not much different than starting in 70F.