AC and idle in a 1970

[davepl]

My 1970 402 has factory air; when you turn on the AC, naturally the RPMs drop and sometimes, if you don't have an artificially high idle to start with, it wants to die.

There's nothing I can see on the 1970 that bumps the throttle up, and if you just run a higher idle, there's no anti-diesel relay that I know of for 1970.

So what's the deal with the 1970? What's the right way to balance this whole "higher idle to handle the AC kicking in, but not so much that it diesels when you turn it off?"

[7tee]

Maybe using a "fast idle solenoid" would help...ed...

[davepl]

I bet it would. Should a 1970 have one? Anyone have pics of a setup? Mine had none when I got it.

[Davidf]

Same problem with my '71. My anti-dieseling relay does not work (have replaced and checked wiring). I have the timing advance for added performance which contributes to the dieseling problem. My solution: In the winter, I slow the idle down since I rarely use the a/c. In the summer, when a/c is used 100% of the time, the idle speed is set higher and the engaged a/c prevents dieseling. For the in-between times, the idle is set for a/c use and I leave the auto trans in gear when shutting of engine if a/c is not being used.

[NC_John]

this is here because I can't delete a message. Thought I had an idea but reread above and decided not.

[Wrenchbender Ret]

I have some idle selinoids for Q-jets but looking at a 69 it does not have the bosses for it.

[davepl]

I wonder, then, some applications needed it and some didn't. I could see that maybe the cam on a 375hp motor is more sensitive and needed help whereas our 310hp didn't?

Not a big deal, just curious as to why the factory figured nothing was good enough!

[FirstOwner69]

My 69 (350) with A/C has never had an idle solenoid. I think they came along later, maybe 71 or 72. Perhaps some 71/72 owners can provide some insight.