Nick: I came in late on this one and am curious about Mike B's recipe for setting the idle.
As I understand, he suggests that one set the throttle adjustment screw so that it does not touch the fast idle cam, thus insuring that there is no gap between the throttle plate and the inside wall of the carb. For a 34 PICT-3, Bentley suggests that the screw be turned in to touch the cam and then another quarter turn. I've read where the pitch of the screw is such that this translates into a gap of .004" between the tip of the throttle plate and the carb. I've always just blindly followed the Bentley recipe and have not explored other settings. It sounds as though Mike B's experience is so vast that I ought to pay attention. Mike, if you're reading this, could you chime in to comment on this possible discrepancy? Thanks, Jack >Thanks for the great advice Mike. > >I think I adjusted the carb correctly according to the Bentley's. >The throttle screw is not contacting the choke cam which is fully >rotated down and the volume screw is all the way in. Still the idle >is too high and it hesitates off of idle. > >A spray of choke cleaner near the throttle shaft causes increased >engine RPMs which tells me that there is a vacuum leak around the shaft. > >As you can tell, I'm quite disappointed that after only a year of >daily driver use, my carb is essentially shot and I'll have to fork >out another $200 or so for a replacement. I was hoping there were >better options. There is a guy at the BugOut that always has rebuilt >carbs but I don't know if they are rebushed or not. Maybe I'll talk >with him and see if he has a good one. > >I figured as much about the Holley. I see forum notes about them but >no talk about it being a "must have" item. > >Cheers, > >Nick >VintagVW > http://homepage.mac.com/stokester/VintageVW/ >Dub~Tunes > http://homepage.mac.com/stokester/dub_tunes > > > >On 24 May, 2007, at 18:41, Mike wrote: > >> Nick, >> >> The 34 PICT-3 carb should have the throttle completely closed at >> warm idle. The automatic choke cam should be fully rotated down >> when fully warmed up. That means that the throttle lever's >> adjustment screw should have a tiny bit of clearance between it's >> tip and the choke cam's smallest step. This is proof that the >> throttle plate is fully closed inside the carb barrel. This brass >> plate has a small hole in it to meter basic idle airflow when the >> plate is fiully closed. The fine idle air adjustment is then >> controlled by the volume screw. If that's fully closed by turning >> it all the way in, the engine should die, due to being almost >> completely deprived of idle airflow. >> It sounds like you're engine is revved up too high at idle, due to >> the throttle lever screw being adjusted too far in, which is >> holding the throttle plate partially open. This causes the large >> volume screw to be almost completely ineffective, as it's being >> bypassed. The auto choke not fully opening proiperly, due to >> misadjustment, bent linkage or a bad electric choke heating element >> or bi-metallic spring.. The choke can may not be opening to the >> smallest step, artificially holding the throttle plate from fully >> closing upon complete warmup. This would cause the same problem >> and waste fuel, too. I've found many carbs (even new out-of-the- >> box!) misadjusted this way, due to some previous person fiddling >> with the screws and not knowing exactly what needs to be done to >> make it work properly. >> I've rebuilt dozens of all types of carbs, re-bushed worn throttle >> shafts, and test run them to check for proper operation, leaks and >> to adjust the basic settings, so that a customer could >> theoretically just bolt it on and run it as-is. AFAIK, the >> Pierberg should be a quality item, the Brosols being a pretty >> decent carb, too. >> You shouldn't try a Holley Bugspray, they stopped being popular > > many years ago for a reason. They just aren't a good carb for >> this application. Yes, they work on a bug engine, but not properly, >> according to what I've read about them. >> HTH, >> Mike B. >> >> ----- Original Message ----- From: "Nicholas Stokes" >> <[EMAIL PROTECTED]> >> To: "Air-Cooled Volkswagen Discussion List" <[email protected]> >> Sent: Thursday, May 24, 2007 5:45 PM >> Subject: Re: [vintagvw] Is There a Quality Carburetor Out There? >> >> >>> as a followup to my carb problem... >>> >>> My daughter brought the car to me saying that it would not idle. I >>> confirmed this and quickly adjusted the volume screw to let her get >>> home and made plans to work on it in a couple of days. >>> >>> After setting the valves and timing I was unable to bring the idle >>> down to about 900 rpm even with the volume screw all the way in. >>> This caused me to spray some carb cleaner near the throttle shaft to >>> confirm the vacuum leak. >>> >>> The biggest issue is that this Pierburg is advertised to be "German >>> Technology" and no where on the carb or packaging does it state where >>> it is manufactured. This in itself says a lot. It has only been in >>> use for about a year now and I have replaced the float and now the >>> wear on the shaft. If these are supposed to be better than the >>> Brazilian/Mexican made Brosol, it was not proven by me. >>> >>> I'm headed to Bug Out in Manassas VA this weekend. Anyone have a >>> recommendation for a decent replacement? >>> >>> This is a daily driver with a stock 1600 and SVDA dizzy. Is there an >>> advantage to finding a Holley Bug Spray? The Webers are too pricey >>> for me. Any other carbs? >>> >>> I see AirCooled.net has a complete dual setup using Solex carbs but >>> I've always been hesitant to add the complication of two carbs. >>> Anyone have experience with these? >>> >>> Thanks, >>> >>> Nick >>> On 3 May, 2007, at 20:58, Nicholas Stokes wrote: >>> >>>> Is there a decent 34 PICT-3 carb available out there? >>>> >>>> I purchased a new Pierburg hoping that it along with my SVDA >>>> distributor with a CompuFire ignition would keep my daughter's '74 >>>> Standard happy for quite some time. >>>> >>>> Well... the distributor from AirCooled.net works great and gives >>>> the >>>> smooth acceleration and performance I had hoped for but the carb has >>>> not lived up to expectations. The first problem at about six months >>>> was flooding out which was diagnosed to be a split float full of >>>> fuel >>>> which I replaced with one out of a 30-year old one in the parts bin. >>>> Now, a few months later, there are signs that it is leaking around >>>> the shaft. >>>> >>>> Any recommendations out there? I'm not looking for any extra >>>> performance, just something reliable. All though an extra boost >>>> would be acceptable as long as it works properly with the SVDA >>>> dizzy. >>>> >>>> Thanks, >>>> >>>> Nick >>>> VintagVW > http://homepage.mac.com/stokester/VintageVW/ >>>> Dub~Tunes > http://homepage.mac.com/stokester/dub_tunes >>>> >>>> >>>> >>>> _______________________________________________ >>>> vintagvw site list >>>> [email protected] >>>> http://lists.sjsu.edu/mailman/listinfo/vintagvw >>> >>> _______________________________________________ >>> vintagvw site list >>> [email protected] >>> http://lists.sjsu.edu/mailman/listinfo/vintagvw >> >> > >_______________________________________________ >vintagvw site list >[email protected] >http://lists.sjsu.edu/mailman/listinfo/vintagvw _______________________________________________ vintagvw site list [email protected] http://lists.sjsu.edu/mailman/listinfo/vintagvw
