Aircon carberrettors.

BX Tech talk
adamskibx
BXpert
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Joined: Fri Jul 22, 2005 9:26 pm

Aircon carberrettors.

Post by adamskibx »

Hello. I have removed the engines of my two BX's ready to put the TRS engine into the GT once all posible sources of oil leaks have been sorted out with new seals. Only thing thats bugging me is that the carb from th TRS engine is one specifically designed for a car with aircon. There are two air pipes that lead to something under the battery tray that supposedly do something to the carb to keep the idle speed the same even when the aircon is turned on. I could use the original GT carb, but the carb on the TRS was brand new 2 years ago so I want to use that if I can. Does anyone know what I should do with the two pipes that come off the carb when the engine in in the GT? Cheers, Adam.

jeremy
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Post by jeremy »

This device is intended to increase the idling speed when the aircon compressor cuts in - so the device under the battery is probbaly some form of electrical valve which may simply open/block the pipe.

Often there are units bolted onto a standard carburettor base in which case you may be able to transfer the appropriate parts from one carb to the other - which would be the neatest solution. Otherwise I'd suggest you fit the thing and then work out if the pipes should be connected or blocked. if you have the valve I'd see if you can blow through it with no current and then with current. The valve will operate with the current turned on - so its the no-current state that you need to achieve.

jeremy

adamskibx
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Joined: Fri Jul 22, 2005 9:26 pm

Post by adamskibx »

Thanks Jeremy that makes a lot of sense. Something to experiment with once its all installed. Its quite odd as the one pipe comes from a big plastic bellow type thing on the carb and the other comes from the section between the carb and inlet manifold so id imagine when the aircon is on, the pipe is allowed to open and the amount of vacuum influences the amount of fuel and air going into the carb. Very odd stuff indeed. Got a quote for the two crankshaft oil seals today; £28!! Seems excessive to me but GSF only seem to do the front seal, not the rear, so I might have to go for it and spend £28 for two litttle seals! The flywheel was slightly damp on the inside, and the cambelt, although recent, was very slightly oily for the first 3mm, and looked like something had been nicking at it for the first 3mm too-id imagine thats just the damage the oil has done.

jeremy
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Post by jeremy »

My guess is that the bellows you mention is connected to the throttle linkage and opens it a bit when it contracts. The pipe from the carb/manifold joint is simply a source of power for the bellows as its in an area of depression especially when the throttle is closed.

If I'm right you will have to block off the pipe at the bottom (manifold/carb joint) before the engine will idle - as otherwise it will allow air to leak into the manifold and mess up the mixture. The pipe to the bellows can be ignored!

jeremy

adamskibx
BXpert
Posts: 950
Joined: Fri Jul 22, 2005 9:26 pm

Post by adamskibx »

Aha yes good thinking Jeremy. Thats almost certainly going to be how it works. Thanks for sussing that out for me