Stutz28

Hi All,

I have a 66 327/300 that is idling too fast. When I first start it and it is warming up, it idles about 600-700 which to me seems and sounds normal. However once I start driving it, it won't idle under 1200 RPM.

Any suggestion on how to adjust this or if something needs to be repaired/replaced?

Thanks for all the help!

Nowhere Man

Sounds like you have junk in your carbs idle circuit

DansYellow66

Could be the idle return spring is too weak to return the throttle to idle. If you blip the throttle does it idle down? Also, look for any place where the throttle rod might be dragging such as on the ignition shielding. And finally, is your choke and fast idle functioning? Could be the engine is struggling to idle on a cold start up due to lack of choke and fast idle setting - but once warmed up is settling into an idle that is adjusted too high. You should be able to lower the hot idle down to the 700 rpm area - can you? If so, I suspect it's a cold start/choke/fast idle issue.

Mike67nv

The '67 Overhaul Manual has an excellent section on carburetors, including all the Holley adjustments. I suspect the ’66 is similar.

karkrafter

Because it's cold out the choke isn't opening all the way and it waffles between high and low idles. Drove my 66 today and it did the same thing...it will be fine in the spring...

65GGvert

IF that's true, your choke isn't adjusted properly.

tbarb

Do you think these cars were like that new?

To the OP, make sure the engine is in good tune and get a Holley manual for your car's engine and go through the Holley carburetor adjustments.

Until you do that all anyone can do is guess at your problem.

karkrafter

You bet your bippy they were like that new...


Turn on your way back machine...Most cars with chokes in the old days had to be set for winter months and summer months. Today most [many] cars with chokes hibernate in the winter months...but not in this case.

tbarb

If I turn on my way back machine and go back all bets are off.

You are correct that they were cantankerous but I maintain the fact that the Holley manifold choke stove worked pretty good. It's just everything else about the Holley's seemed to be problematic.

Gotta start with all basic adjustments and go from there. You may be surprised how many people still don't know how to adjust the accelerator pump correctly then start throwing $$$ at a problem they don't have.

Powershift

I grew up in Chicago..................and never had a winter and a summer choke adjustment. I set it once and it was fine after that. Maybe I was just good.

Now we did have winter and summer thermostats (195 and 170 F) and winter and summer oil (20W-20 and 30). With the older high-milage cars I drove back then 10W oil was way to thin and the oil pressure gage told me so.

Larry