Hi folks -- time to get more technical again about my Porsche 911. Inadvertently I started fooling around with the carbs last fall due to a mistake with a technician leaving the hand throttle slightly on after servicing the heater control on the vehicle. So I messed with the idle screws and that was not good. After a knee replacement and a long cold winter, I finally got to getting those cars straight last week. In the meantime I set idle mixture screws at 1 1/2 turns out air screws closed, and idle screws on the two carbs at 1 1/2 out.
My key tool is my Uni-Syn synchronizer. I first got this in 1966 when I owned a 1959 MGA after high school.
Begin by disconnecting preheat hose to air box, three hoses that connect oil breaker, drain and evaporate system, and take off the air box.
Before you start! The very best advice I can give you. Back off the idle speed screw on both carbs until they do not touch the throttle lever. Turn speed screw in until they contact lever and then turn it in 1 1/2 turns. Repeat with the other carburetor. Turn each idle mixture screw in until it lightly seats, then turn out 2 complete turns. Air by-pass screws air to be closed. This is a very good start for carbs that are in good shape.
First and assuming that valves are set properly and dwell and points gap are correct, disconnect the two cars from each other. You do that by using an 8 mm open wrench, wedge it in the ball mechanism, and gently separating the joint. Idle should be at 1000-1200 rpm.
Put the Unit-Syn on intake for #1 cylinder and then set float to a major mark. Move to carb on the other side, and then adjust idle until you get the same suction. Next work your way through each one of the mixture adjustments, maximizing mixtures by turning each screw in until idle drops, the back off 1/8 of a turn.
Then find the air adjustment screws near the bottom of the carbs. Using an 8 mm box wrench, loosen nut and turn screw for each one of cylinders until each have the same suction as demonstrated with the Uni-Syn.
You are now pretty much set! Put stall back together and enjoy year ride. I noticed that I got more power and higher speeds at fixed rpm then previously.
There are several youtube videos you can find to help you. Also see Wayne Dempsey's excellent write-up at the Pelican Parts site.
My key tool is my Uni-Syn synchronizer. I first got this in 1966 when I owned a 1959 MGA after high school.
Begin by disconnecting preheat hose to air box, three hoses that connect oil breaker, drain and evaporate system, and take off the air box.
Before you start! The very best advice I can give you. Back off the idle speed screw on both carbs until they do not touch the throttle lever. Turn speed screw in until they contact lever and then turn it in 1 1/2 turns. Repeat with the other carburetor. Turn each idle mixture screw in until it lightly seats, then turn out 2 complete turns. Air by-pass screws air to be closed. This is a very good start for carbs that are in good shape.
First and assuming that valves are set properly and dwell and points gap are correct, disconnect the two cars from each other. You do that by using an 8 mm open wrench, wedge it in the ball mechanism, and gently separating the joint. Idle should be at 1000-1200 rpm.
Put the Unit-Syn on intake for #1 cylinder and then set float to a major mark. Move to carb on the other side, and then adjust idle until you get the same suction. Next work your way through each one of the mixture adjustments, maximizing mixtures by turning each screw in until idle drops, the back off 1/8 of a turn.
Then find the air adjustment screws near the bottom of the carbs. Using an 8 mm box wrench, loosen nut and turn screw for each one of cylinders until each have the same suction as demonstrated with the Uni-Syn.
You are now pretty much set! Put stall back together and enjoy year ride. I noticed that I got more power and higher speeds at fixed rpm then previously.
There are several youtube videos you can find to help you. Also see Wayne Dempsey's excellent write-up at the Pelican Parts site.
No comments:
Post a Comment