PV judging question: allowable ranges for idle speeds

[Gary B.]

In PV judging, how do the judges know reasonable ranges for slow and fast idle speeds? I know the speeds vary by engine and year, so is there some chart that says what the acceptable ranges of slow and fast idles speeds are for a specific year and engine?

Gary

[Michael J.]

Re: PV judging question: allowable ranges for idle speeds

If you look in the PV manual for your car, you will see the ranges by engine.

[Gary B.]

Re: PV judging question: allowable ranges for idle speeds

Ah, a manual I don't have! Thanks.

Gary

[Duke W.]

Re: PV judging question: allowable ranges for idle speeds

Fast idle speeds (that are set hot) are usually listed in the service manual fuel system spec session, and cold fast idle is usually about 2-300 revs less on initial start up. "Curb idle", which is when fully warmed up is vague. It may not be specifically listed in the service literature, but it can be implied from the ignition advance specs as the start speed for centrifugal advance, but that's not necessarily the answer. For example, my 340 HP SWC centrifugal starts at 700, but it's near impossible to get a Duntov cam to idle at 700 with reasonable quality and stability. It's takes more like 850-900.

I haven't seen all the curb idle speeds in the JGs, but the ones I've seen give a reasonable range.

Modern engine control system usually maintain idle speed to within less than one one percent of nominal, but on these old cars with their simple mechanical analog control systems you have to give some latitude.

Duke