Still haveing trouble with this 870. Once warmed up, while cruzing if I disengage drivetrain the idle hangs up around 2k rpm until I kick the throttle down and it will stay at 900. I do not have any vacuum leaks in the intake manifold. Replaced base gasket numerous times no leak there either. Will a blown power valve or power valve of the wrong size allow fuel in to cause this? Since this is a 4-speed car should I be using a #5 power valve if I have 11 inches of vac and do you match them for the secondary side as well? Any suggestions are appreciated. Thanks Rich

Does it have a choke? If so sounds like the fast idle is sticking.

oger,
No choke, all choke related harware was removed.

Your mechanical advance could be sticking. the extra timing at idle will make it idle fast like that. With 11" vacuum at idle I would use a #5.5 PV, although a 6.5" PV should work fine too.

I had a PV rated at 6.5" and the car would idle in gear at 5 - 7". Well it made the car to weird things like you are describing but its an automatic car. I wondered why I had so much trouble getting the idle AF mix set right :rolleyes:

I bet its a vac leak though . . .