mhorvath

Hello everyone.
I've been having a little problem with my 83 RX7, in that it refuses to idle below 1200 and still runs a bit smokey and rough there. Here is the set up.

Rebuilt 12a, Holley 465 Carb, RB manifold, RB headers.

I have set the timing, the float levels, and the choke. The idle mixture screws have been adjusted to every plausible position, with nothing seeming to help. No matter how far I back out the idle speed screw, rpms will not drop to the desired 800. The engine never really seems happy idling, with some pretty acrid smoke coming out sometimes in puffft, pufft, pufft bursts.

At this point I'm at a loss for what to try next. Any wisdom or experience out there on the subject? Thanks.

Bruceman

iTrader: (5)

"No matter how far I back out the idle speed screw, rpms will not drop to the desired 800. The engine never really seems happy idling, with some pretty acrid smoke coming out sometimes in puffft, pufft, pufft bursts. "

Sounds like an air leak which is making it run lean and the exhaust stink. An air leak below the throttle butterflies also accounts for the inability to lower the idle speed.
Although not familiar with this carb setup suspect the air leak to be at some vacuum port/hose or a carb manifold gasket.
Many people use some kind of fluid (carb cleaner, propane, WD40) to spray around suspected vacuum leaks and listen for a change in the engine speed/note to find the leak.

Good Luck

mhorvath

Hey, just wanted to let you know that your reasoning about the air leak was valid, if not exactly what was going on. I found an adjustment screw that was keeping the secondaries partially open, leading to my problem. Having closed them more, idle will now drop down below 1000. Things still aren't perfect, but I am so glad to be on the right track now!

Is there any reason for me to leave the secondaries open at all? I wonder because the adjustment screw must be there for some reason. If anyone knows the proper setting for this type of thing, I'll be greatly in your debt.

Thanks.