idle speed

[Sovereign]

Hi all,

I finally got my hands on a laser tachometer so I could set my idle speed properly. This is part of my efforts to baseline the truck before I start making changes or major repairs. The truck was and is running well. I just had my idle set based on feel.

I followed the instructions on the emissions tag under the hood and with the engine warmed up and vacuum advanced disconnected and plugged, I set idle speed to 550rpms with the truck in gear. Timing was at 4-6* advanced so I left it alone.

I plug the vacuum advance back into the distributor and idle speed in gear goes up to 750 rpms.

When I move back to park, idle speed is now 1050-1100 rpms.

Does this sound right for a normal idle speed? The truck is running fairly smooth at all these speeds. It drops into and out of gear without heavy jerking. To me, it's just higher than I was expecting.

I did not check timing after plugging the vacuum advance back in. I was running out of time and didn't think to check that. I do know the previous owner installed a normal HEI so I do not have ECS control any more. Could it have lighter springs that are advancing the timing too much. Assuming that idle speeds I am seeing now are too high that is.

I have not adjusted the idle mixture screws from where they were before I did these idle speed adjustments to see if that has any effect. I do not have any external vacuum leaks. As I said, the truck is running well.

Thanks