Need unconventional wisdom for weber tuning

[mopar_ja]

Sorry i have not been on for awhile, screwing with this weber triing to tune it. Here is the senerio. Fallon sits at 3900 and some change in ft. above sea level. Conventional weber tuning says i should be running about a 40-50 primary idle jet. To achieve best lean idle i should only be 1 to 2 turns out on idle mix screw. Here is the problem in order for me to achieve this, ( I HAVE NO IDLE JETS ) on either side and mix screw is about 1 1/4 to 1 1/2 turns out, my timing is just about dead on at 10 degree BTDC. Does air correctors have anything to do with this i read that the air correctors do not come into play until about 4000 rpm or is this incorrect. i have the haynes weber book can not find any info about my problem. So i welcome all unconventional rational or whatever suggestions my help me with this thanks guys.

[camoit]

There were jets in the weber box. I think there was air jets also. You need to preform a lean idle tune. Thats where you start by turning the idle speed screw back and close the butterfly. But keep it running by adjusting the mix screw out or in. Once the butterfly is closed completely then turn in the mix screw 1/4 to 1/2 turn. Use the idle speed screw to set the idle back up to where it runs OK. What is it doing, stalling when you hit the brakes hard?

[mopar_ja]

It idles fine at about 850 rpm, drives fine when just putting up and down my buddies drive way. Yes: backed idle screw out till no contact and turned in till i just made contact and about 1/2 to 1 full turn in beyond that. Then by "conventional" weber tuning methods decrease primary idle by 5 for every 2 thousand feet above sea level beyond roughly 2000 ft mark. which should put my primary idle jet at 50; 10 below stock setting which is a 60 primary 50 secondary idle. Problem is in order for me to achieve best lean idle condition with 60 pri idle jet i am 6 to 7 full turns out on idle mix screw, which by weber tuning i am too lean. I need 1 to 2 full turns out on mix screw which i can only achieve by having NO IDLE JETS at all. i have every idle jet made by weber for this carb both primary and secondary. even with 95 primary ( biggest made by weber ) idle jet i am still too lean about 3 to 3 1/2 turns out on mix screw. Conditions with carb set like this: PI 95, SI 80: PAC 175, SAC 190: PM 120, SM 180: APJ 50. Idles fine, crack the throttle from idle hesitation then picks up, stumble at about 2300 rpm up. Goal remove hesitation when cracking from idle and remove stumble above 2300. from what i was reading all stumbles and hesitation are from not enough fuel. so i removed all idle jets hesitation virtually gone when cracking throttle from idle. so was thinking i will try this tomorrow decrease air correctors to hopefully richen up and increase main jets to see if stumble goes away.

[camoit]

no jets. Sounds like somthing is plugging some ports or somthing. Or the float is to low.

[pennyman1]

What is the fuel pressure going into the carb? Most people think it should be 2.5 to 4 PSI; however this is dependant on a few factors. If you are running the stock fuel pump(mechanical) through a reg before the carb, it will ruin the pump in short order due to the back pressure from the reg. If you are running an electric pump at the outlet of the tank, it should be 5-7 PSI to allow for line pressure loss. Webers also require high flow rates at pressure - the higher gph the better - to run correctly. At your altitude, that thing should be running rich to the point it should be looking like a diesel from black smoke.

[pennyman1]

I realized that you already went to the electric pump if this is the truck you built the setup for on the blog. Pull the fuel filter out of the carb - its just past the inlet fitting - and check for dirt clogging the filter. Next, check the needle and seat for dirt, teflon tape, or other debris. With that pump, there should be no reason for the lack of fuel you are experiencing. Be sure you are using the larger of the fuel lines to the carb, as the return is smaller and may have a check valve in it to prevent fuel from flowing back through it in case of rollover.

[mopar_ja]

Sorry i have not been on for awhile, i found most of my problems i developed a vacum leak at rear of intake and below the carb. So in short pulled head replaced intake gasket with custom (made by me) one. Now i have a mild port and polish after using rat tail file, and just played around with the jets my to get best running condition. My current jetting is PI: 85; SI: 75; MAC: 155; SAC: 160; MJ: 135; SJ: 180 and about 3 turns out on mixture screw, running like a champ!! YEAH!!! get about .5 to 1 second delay when flooring it so i am very happy and its very drivable hoping to get it liecensed and on the road by next week.