AC on GMC 270
 

I have a 54 GMC truck 270, headers mild cams, Holly 490, Clifford manifold, HEI. I Installed after market a/c, works great but at idle, with the compressor on it wants to die, or stumble. Going down the road its fine. I've adjusted the carb, but I can't go too high on the idle, any ideas?. thx BMT

Re: AC on GMC 270
 

Just a thought - I have seen some carbs on several different brand vehicles [unfortunately with my memory i cannot remember which engines] that have a little solenoid connected in line with wire that kicks on the compressor. The solenoid has a little bracket and arm that bumps against the throttle arm and raises the idle speed when the compressor kicks on. When you throttle up above idle the little arm stays extended but since the throttle arm is up, it doesn't matter.

I may actually have on of those in one of my garage stacks of "stuff." If I do then I will just let you have it to see if it will fit.

Re: AC on GMC 270
 

Wow, very gracious of you. I was going to check on the holly web page to see if they recommend a solenoid configuration as you described, or the vintage air folks to see if I missed something. Can I send some $$ for the shipping ? Thx bmt
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Re: AC on GMC 270
 

If your truck has the original hand throttle you may need to just pull it out a little when running the ac. Other wise, Ray is right the 60's cars with ac had what he described, I changed out the carb and manifold on my original 64 and had to go back and rig one up so it would kick the idle up.

Re: AC on GMC 270
 

Those should be pretty easy to find as they were on most GM cars with ac in those years.
you will have to fabricate a bracket though.

Re: AC on GMC 270
 

Thanks, I'll check it out, also , I e-mailed Holly carb tech page to see if they have an application that would fit. bmt

Re: AC on GMC 270
 

BMT,
I found the solenoid, hooked up to a battery and it doesn't work. It is the fast idle solenoid off a Motorcraft 2100 2 barrel carb found a bunch on those blue oval type cars. It is really cool though - the solenoid sits on a small base connected to a screw drive on a bracket so you can move it back and forth to adjust the fast idle.
My Mustang buddy tells me these carbs are everywhere and usually cheap! Happy hunting and sorry I couldn't help

Re: AC on GMC 270
 

Hey great info!, you did help and it's appreciated. I'll see if I can round one up. BMT