66 L72 fast idle after warm up
I would like some suggestions on how to cure a faster idle after the engine is warmed up. When started cold the idle is between 700 & 800 rpm, which seems to be about right. After warm up the idle jumps to around 1100 rpm. If I lower the cold idle it will stumble & stall. It has an original 780 cfm Holley, but I have eliminated the original ported vacuum & modified it for full vacuum at idle. It doesn't seem to have any vacuum leaks.
-
-
Re: 66 L72 fast idle after warm up
700-800 fast idle after a cold start isn't even in the ballpark.
I suspect your choke or fast idle system is not properly set up. The CSM has the procedure and specs for setting the choke and fast idle, which may require bending some of the links and then setting the fast idle speed with the engine hot.
On a cold start the fast idle speed should be about 2-300 revs less than the hot specification in the CSM that you set it to, so if the hot fast idle speed is specified at 1800 the cold fast idle should be about 1500.
I recommend a fully warmed up idle speed of about 900 for L-72, and the engine should be pulling about 14" manifold vacuum.
The OE "360 12" 12 deg. @ 12" VAC is okay for full time advance as long as it actually works and meets spec.
It's normal to have to readjust the fast idle speed after converting to full time vacuum advance, and one must also go through the hot idle speed/mixture adjustment procedure after the conversion.
Duke
Comment