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MG MGB Technical - Generic Carb kick-up idle switch for A/C?

I've been posting around trying to find a suitable electric kick-up switch that would fit the B (SU's)
so the idle doesn't drop when the compressor comes on.
Any comments appreciated.
Samuel Sullivan

Sam, no answers but I'm with you. Some time ago, a mechanic-friend told me to try a switch from an older carburated Isuzu, but I have not tried this yet. ' Just checked the A/C in the Moss catalog hoping to learn something about how they handled this problem - but to no avail.

So far, my only solution has been to shut the A/C off at stoplights, etc. otherwise the engine dies altogether - even with my idle set way up. Let's hope somebody has an idea.

Cheers,
Allen
Allen Bachelder

These existed on every US built car I have had with air. Do a little searching at your local junk yard or parts house.
John H

You might be able to use this:
http://www.holley.com/HiOctn/ProdLine/Products/FMS/FMSCA/46-74.html

Wayne
Wayne Pearson

Wayne,

Thanks! That could probably be made to work, although a little pricey. ' Think I'll check out the junkyards for something cheap first - just to see how much fussing is involved to make up a bracket that works. ' Hate to spend $82 + $7 (for the fixing nut) and then find out it can't be made to work.

Cheers,
Allen
Allen Bachelder

I simply adjusted the choke linkages so that pulling the choke out 1/2" raises the idle without enriching the mixture (that is, without moving the jets). When I run the a/c, I just pull the choke out a little. -G.
Glenn G

Glenn,

I probably could make that work with some more playing with the adjustment. As it is, that first half-inch will increase the idle to nearly 2000 rpm without the A/C and yet the compressor will pull it down to under a stumbling 500 rpm. Part of my problem is that this engine never idles twice at the same rpm anyway. I'll get it idling beautifully at right around 1000 rpm, take it out on the road and two blocks later at a stoplight it will either be idling at about 15-1600 rpm or it won't idle at all. The next stoplight after that will be the other extreme. Once under power this car runs GREAT and on the open road it gets 30-34 mpg. Can't ask for more - except it never idles worth a d*mn.

It may be time to send these carbs off to Joe Curto.

Cheers,
Allen
Allen Bachelder

Samuel: a junkyard tour should be in your future,envision your design, and find your parts.
send us some pix. RIC
RIC LLOYD

How about fixing it the other way round and have a limit switch on the carb or throttle pedal that switches the A/C off at idle?
Chris at Octarine Services

Chris,

Now why didn't I think of that? ' Guess that's why you're in the business! I expected a barrage of posts telling me what I need to do to fix the idle. Since I'm not, may I presume everybody else has the same problem. I've driven a whole bunch of MGBs over the last 24 years and I can't remember any of them that didn't have this problem.

Two possible conclusions:
1. They all do that.
2. I'm making them all do that.

So, which is it?

Many thanks,
Allen
Allen Bachelder

Allen

It must be your magic touch. Neither my 58A or 72 BGT have an unstable idle when warmed up.

Larry
58A
72 BGT daily driver
69C (2) in restoration
Larry Hallanger

"How about fixing it the other way round and have a limit switch on the carb or throttle pedal that switches the A/C off at idle?"


Washington, DC.
5:00 pm rush hour.
Mid-August.
98* F.
80% humidity.
Interstate 66.
Two miles in 20 minutes.

High idle is your friend. :)


Rick Stevens

Rick,

Having lived primarily in rural communities these past 30 years, I had forgotten about that. ' Guess it depends on what kind of driving you have to do. ' Glad to hear you're using your B!

Cheers,
Allen
Allen Bachelder

Allen - MGs with worn carburetor throttle shafts (or other vacuum leaks) have trouble sustaining a constant idle speed. It is a common problem, but not universal. -Glenn.
Glenn G

Glenn,

I was wondering about that. These are HIFs which are less inclined toward that problem, but nevertheless, I've owned this car since 1986, it has well over 200,000 miles on it, and I rather doubt that these carbs have ever been rebushed. ' Guess it's time for that.

Thanks!
Allen
Allen Bachelder

This thread was discussed between 15/01/2008 and 19/01/2008

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