> Mike: Very informative. Thanks, Jack
> I'm recommending this particularly for a carb that has demonstrated some >throttle bushing wear. The idle circuit on this carb is very touchy, and is >easily thrown off by this leak The idle air can flow thru the hole in the >butterfly, plus thru the cracked-open throttle setting, plus thru the worn >bushings. All this air flowing makes it practically impossible to adjust >the idle properly with the 2 idle adjustment screws (large upper screw = >idle air/ small lower screw = idle fuel). BTW, this is "idle-only" >settings. Anything above idle is controlled by the main jet, emulsion tube >and venturi sizes, plus the accelerator pump nozzle and stroke adjustment to >add fuel during acceleration, and the enrichment passages during WOT (wide >open throttle). The choke butterfly, heating element, bi-metallic spring >and vacuum pull-off must all be working properly to allow all these other >circuits to perform properly under all the various conditions. > For the 009 distributor hesitation problem, Boston Bob even recommends >installing a pop rivet to close off the butterfly hole, to allow better idle >transition and acceleration adjustments to help compensate for that >particular syndrome. > The .004 gap you're referring to is for a clean, perfect, unworn, >unmolested carb. Not much of those left around anymore. When they instruct >you to 'lightly' close the idle volume screw, they mean VERY lightly, >because the pot metal carb body is so thin at the seat for this screw, that >it is easily distorted and permanently damaged by tightening it too much or >too many times by too many 'mechanics'. This damage changes the shape of >the seat and the screw needle adjustment is never going to work properly >again. This damage is not repairable, and now you need a new carb, even if >the throttle shaft bushings aren't worn out yet. > I've rebuilt every carb VW has ever made (except the oldest bug ones and >the Rabbit 2-bbl). I've repaired and re-bushed dozens of them, and adjusted >and balanced too many to count. Just my own recommendatons, due to my own >personal experience, that's all............ > >HTH, > >Mike B. > >----- Original Message ----- >From: "Jack Dinan" <[EMAIL PROTECTED]> >To: "Air-Cooled Volkswagen Discussion List" <[email protected]> >Sent: Thursday, May 24, 2007 9:16 PM >Subject: Re: [vintagvw] Is There a Quality Carburetor Out There? > > >> 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 >> > > >_______________________________________________ >vintagvw site list >[email protected] >http://lists.sjsu.edu/mailman/listinfo/vintagvw _______________________________________________ vintagvw site list [email protected] http://lists.sjsu.edu/mailman/listinfo/vintagvw
