Before I start twiddling random screws.... what is th proceedure to balance the carbs using a manometer ( this is a dual pipe manometer )
Thanks
Balancing 36 idf with manometer
Re: Balancing 36 idf with manometer
Hi Faffm - I guess with a manometer you will be hooking up to the vacuum take-offs at the base of the inlet manifolds? If so, the first order of business is to set all of the idle mixture screws to the same number of turns out from fully home. From memory this should be 2.5 turns or thereabouts.
Disconnect the throttle bar from each carb so that the idle screw can be adjusted individually. Connect you manometer to one carb and start the engine and note the reading on each choke. Hopefully they are more of less equal, but you adjust this last anyway. Swap the manometer onto the other carb and measure the manifold depression. You need to adjust the throttle stop screw on each carb such that the manifold depression is the same for each carb (I suppose you could connect one pipe to the LH carb and one to the RH carb for this measurement). Once the carbs are balanced side-for-side you can go back to the individual chokes on each carb. The readings should be near identical. If they are not, you can adjust the air bypass screw at the base of each choke, but these are often covered by a tamperproof plug (mine were).
finally you need to screw each mixture adjustment screw in until the cylinder starts to misfire, you have to listen for a slight drop in engine note. Once the point of misfire is established you need to back the screw out a half-turn or until the engine note picks up again. This sets the optimum mixture setting for each choke.
Finally you need to reconnect the throttle bar, making sure that the turnbuckles are adjusted so that there is 1mm of free play on each side, and adjust the idle speed.
Hopefully by now your engine is singing sweetly, but if it sounds like a bag of rusty nails, close all the air bypass screws, reset all the mixture screws to the same setting and you are ready to try again!
The above procedure mostly worked for me, but my engine has a burnt valve on #4 cylinder which refused to tune up.
Good luck!
Lauren
Disconnect the throttle bar from each carb so that the idle screw can be adjusted individually. Connect you manometer to one carb and start the engine and note the reading on each choke. Hopefully they are more of less equal, but you adjust this last anyway. Swap the manometer onto the other carb and measure the manifold depression. You need to adjust the throttle stop screw on each carb such that the manifold depression is the same for each carb (I suppose you could connect one pipe to the LH carb and one to the RH carb for this measurement). Once the carbs are balanced side-for-side you can go back to the individual chokes on each carb. The readings should be near identical. If they are not, you can adjust the air bypass screw at the base of each choke, but these are often covered by a tamperproof plug (mine were).
finally you need to screw each mixture adjustment screw in until the cylinder starts to misfire, you have to listen for a slight drop in engine note. Once the point of misfire is established you need to back the screw out a half-turn or until the engine note picks up again. This sets the optimum mixture setting for each choke.
Finally you need to reconnect the throttle bar, making sure that the turnbuckles are adjusted so that there is 1mm of free play on each side, and adjust the idle speed.
Hopefully by now your engine is singing sweetly, but if it sounds like a bag of rusty nails, close all the air bypass screws, reset all the mixture screws to the same setting and you are ready to try again!
The above procedure mostly worked for me, but my engine has a burnt valve on #4 cylinder which refused to tune up.
Good luck!
Lauren
Re: Balancing 36 idf with manometer
Just seen the other post on twin carbs - full procedure therein. D'oh 
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Faffmeister
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Re: Balancing 36 idf with manometer
Belated thanks !!!!