You need to lower the idle speed. To do this you need to work on two adjustments, the throttle stops on each carb and the idle mixture screws. Both settings need to be synchronised on each carb/throat.
This is done by adjusting the idle mixture screws first as the engine runs. Screw all four down till they lightly touch the bottom of their bore. Then unwind each of the four screws exactly one and a half turns. Start the engine. Turn each screw in quarter of a turn and wait 10 secs. If the engine speed increases, unwind the throttle stops to slow the engine revs, making sure both carbs throttles are at the same opening settings (listen to the suction in each carb using a piece of hose in your ear and placed in the entrance of each carb. - adjust the throttle stops until the suction sounds identical in each choke of each carb. You only need to listen to one choke in each carb to do this) Repeat with another quarter turn of each idle mixture screw and repeat above if the engine speed increases. If the engine slows down after the first quarter turns of all idle mixture screws, reverse the turning direction and do the same proceedure. When the engine no longer increases in speed after turning all the idle mixture screws a quarter turn, turn them all back to their last setting, readjust the throttle stops to slow the engine to about 900 - 1100RPM, depending on how "big" the cam is. ----- Original Message ----- From: "Mohit K. Autar" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Tuesday, September 07, 2004 6:59 AM Subject: RE: weber jets... Hi , it idles between 1100-1400rpm.since i have a mild cam in there will this cause that high idle. also it shakes alot when you try to lower the idle.is it possible that it could be sucking air from somewhere. mohit. -----Original Message----- From: rclough [mailto:[EMAIL PROTECTED] Sent: Monday, September 06, 2004 7:44 PM To: [EMAIL PROTECTED] Subject: Re: weber jets... Webers can run with a bit of angle, they feed from the centre of the fuel bowl. It sounds like its lean at idle. I suppose you have adjusted both carbs idle mixture screws and ensured both carb butterflys open at exactly the same time? Balance the idle mixture screws and throttle openings. Try to get it balanced and idling smoothly at 900RPM. Most likely you need richer idle jets, but try above first. ----- Original Message ----- From: "Mohit K. Autar" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Sent: Monday, September 06, 2004 6:15 AM Subject: RE: weber jets... Hi there, well i fitted the twin 40mm webers in my datsun but it not running right.on idle its missing which is very hard to tune but after 3000 revs it starts to get normal and it has good response upto 6500 rev. the other thing is,im losing power but this is not for the carbs but the engine is giving up.i have to overhaul it soon. one thing i have to know.since i made the manifold at home.the webers are slightly tilt when you look from the front of the car. do i have to get it level. Cheers Mohit. -----Original Message----- From: Errol Smith [mailto:[EMAIL PROTECTED] Sent: Saturday, September 04, 2004 1:19 AM To: [EMAIL PROTECTED] Subject: RE: weber jets... I can disagree and will very strongly. I think a lot of time dyno operators produce a result you want. More often the decision to buy a dyno is seen as a licence to print money. The people that run it have no ability how to use the equipment at even 25% of its capacity for diagnostic purposes or do not care. The prime purpose seems to be to relieve you of large amounts of money for no gain or very small increases in performance. The bill for "dyno time" often represents about 5 - 8 times the actual amount of time the dyno was used. A lot of work that should be done else where is done "on the dyno" (parked of course) and you end up paying exorbitant rates for a costly work bench :-) As for results, "The result you want is often achieved by no more than a change of the air temp correction data or a change of wheel diameter" until a suitable "ego massaging" positive result is obtained, regardless of how driveable the machine is. There are a few who know how to use them and are conscientious. The prices for their work seem to be a lot less than the high flyers and often after 5 minutes they will take the car of the dyno and send it for further work so the dyno time is very small. Some of the self promoting experts charge Tattslotto number for results that could be achieved by a 3 year apprentice with a 20 year old vane tune up scope. As for tuning webers, if you have been doing for 30+ years you should be able to pick the setup to use on a car easil within a jet size or two, have it run and be driveable immediately. Later have it dyno'ed to fine tune mixtures with only a small amount of dyno time. When you see people getting a bill for 3 days of dyno time to set up an ECU, you have to wonder about the person using the gear. Did they get past first year apprentice engine tuning 101 :-0 Aaaaaahhh, that feels better. This is aimed at incompetent dyno tuners who rip off Datto owners where ever they may be. There are a lot of them who's bills should make them ashamed of claiming they are engine tuners. When you see a professional on good equipment, you realise how bad some dyno "experts" are. I am tired and going to bed. Night all, Feral Errol --membersozdat------------------------------------------------------- OZDAT Mailing List Please Note:- Send (un)subscribe requests to [EMAIL PROTECTED] Send submissions to [EMAIL PROTECTED] No unauthorised redistribution of this email http://www.ozdat.com/ozdatonline/index.htm http://www.ozdat.com/ozdatonline/listindex.html http://www.mail-archive.com/[EMAIL PROTECTED]/ ---------------------------------------------------------------------
