Sounds like the addition cylinder volume is the problem. The carb cannot keep up with the demands, have you thought about dual kadrons? You will more then likely have to change your exahust if you move to a larger carb setup. --- On Thu 03/20, Bob_Kai Wongthanavimok < [EMAIL PROTECTED] > wrote:From: Bob_Kai Wongthanavimok [mailto: [EMAIL PROTECTED]: [EMAIL PROTECTED]: Thu, 20 Mar 2008 00:59:33 -0700 (PDT)Subject: [vintagvw] Stumble engineBy way of introduction, I'm a new old listee (been with the list few times many years back) from Bangkok, Thailand. I have a 71 RHD Super with recently mod as follow:Existing stuffs:o 1,600 standard single port AS case engine with 30-Pict3 carb - now replaced with belowo 009 dizzy with Pertronix magnetico Bosch blue coil but recently changed to Hitachi Red (my mechanic said it is compatible)o Aircono 831 trannyo Old standard muffler Newly put in (~3 months):o New single 34 Pict 3 Solex (but I think made by Bocar) on dual port (was single port before)o New 76mm CB performance cranko New 88mm Mahle piston set The two should put me to a 1,850cc engineo New 044 CB Performance heads (I think 40X37mm valves). On 34Pict3, I have made some mod according to Nate from AirCooledTech.com by plugging the throttle by-pass hole to boost the vacuum so that 34pict can work with 009 see link: http://www.aircooledtech.com/34pict3_modification/ Here is my problem, whilst running nicely on high rev, the engine stumbles on low rev (below ~1,800 - 2,000 rpm). Situations like this normally occur:a) cruising along the road, turn in to cross street, shift down to 2nd, push gas pedal while releasing the clutch, stumble almost the engine is going to stop.b) cruising along, slow down, shift down to 2nd, same to a)c) cruising, stop on standstill traffic on neutral, the engine stumbly idle. However, after a while, the engine came back to (almost) normal with slight hiccup every minute or so. The symptom is a! s if the gas does not come through sufficiently. On a) & b), I have to push gas pedal a bit (to keep rpm up) together the clutch to hold so not to go too fast. Any idea? My mechanic suspects on 2 things, (1) bad carb (he is kind of not trusting Mexico or Brazil made carbs), or (2) stand muffler cannot cope with such a large engine. thought that exhaust cannot come out fast enough. Oh, BTW, "sometimes", there were some backfire like single firecracker too. Hope it is not too long. Appreciate everyone comments. Bob/Bkk/71 RHD Yellow Super ---------------------------------Never miss a thing. Make Yahoo your homepage._______________________________________________vintagvw site [EMAIL PROTECTED]://lists.sjsu.edu/mailman/listinfo/vintagvw
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