The 350 2bbl didnt get much drive time for several years until I bought it 2 months ago. The more I drive it Ive noticed a "stumble/hesitation" off idle. It accellerates fine after that. The points and plugs were supposedly change less than 5k miles ago. Does this sound like a carb or timing adjustment? Im working on a QJet rebuild for a 4bbl swap and dont want to dig in too deep. Ideas?
[FONT=Tahoma, Verdana, Arial, sans-serif]To start with set the ignion timing to about 8 degrees initial and then tune the carb. If you want to get serious about the timing then read the power timing thread in the FAQ section. [/FONT] [FONT=Tahoma, Verdana, Arial, sans-serif][/FONT] [FONT=Tahoma, Verdana, Arial, sans-serif]If the timing is anywhere close to right then you can just tune the idle mixture screws to smooth out the idle... This usually gets rid of off idle stumbles if they are carb related. [/FONT] [FONT=Tahoma, Verdana, Arial, sans-serif][/FONT] [FONT=Tahoma, Verdana, Arial, sans-serif]If you want a 4bb carb I suggest getting Ken G (Everyday Performance) to rebuild you one. he even found one for my application so we only had to pay for shipping one way. [FONT=Tahoma, Verdana, Arial, sans-serif][/FONT] [FONT=Tahoma, Verdana, Arial, sans-serif]Feel free to ask questions and clarify anything that you are not fully understanding. I do not mind further detailing things.[/FONT][FONT=Tahoma, Verdana, Arial, sans-serif] [/FONT] Turn the idle mixture screws all the way in till they LIGHTLY seat then turn them each out 2.5 full 360 degree turns. This is a baseline and you will fine tune it later. If these are screwed in too tight the tip will be ruined so be gentle. [FONT=Tahoma, Verdana, Arial, sans-serif] [/FONT] [/FONT]There are a few ports on the carb, find one neer the bottom that puts out about 10-14 hg on the gauge at idle (this is called a manifold vacuum source). Use this port connected to the gauge to test and adjust your ilde mixture setting screws. You will need to start the car and put it in gear to do this. BE SURE the car is safely blocked with e-brake on (firewood will work in front of the tires). Watch the gauge as you adjust the idle screws in a quarter turn past your starting point of 1.5 turns out. If the vacuum goes up when you screw them in then turn them another quarter turn in. If the vacuum goes down go back to the 2.5 setting and then out another quarter turn on both. Keep adjusting until the vacuum will not go any higher. Wait about 1 minute between adjustments as it takes a while for the effect to happen. This is how I set the air/fuel mixture for the idle and it makes a HUGE difference in how it drives. Keep in mind you will need to lower the idle speed as you get the mixture correct so after each adjustment put the car in park and check the idle speed and lower if needed. The spec for stock idle is about 650 rpms, and it should be listed on a sticker above the radiator. :beers2:
