Following are three GMC related comments I have been curious about.
What's your opinion/experience?

Is extended idling detrimental for our 403/455 engines? At break in it is suggested to run at higher rom -- but what about idle time max for "broken in" engines? I have read people running at idle for two hours to charge the batteries.

Will placing the key in the run position (engine off) for an extended period burn the points on the early points/condenser ignition? Someone once mentioned this in connection with leaving the key in run to allow the compressor to pump up the airbags.

What benefits accrue from "drive it like you stole it" -- this is occasionally mentioned in connection with engine performance.

Dennis S wrote on Mon, 11 January 2016 16:21

Following are three GMC related comments I have been curious about.
What's your opinion/experience?

Is extended idling detrimental for our 403/455 engines? At break in it is suggested to run at higher rom -- but what about idle time max for "broken in" engines? I have read people running at idle for two hours to charge the batteries.

Will placing the key in the run position (engine off) for an extended period burn the points on the early points/condenser ignition? Someone once mentioned this in connection with leaving the key in run to allow the compressor to pump up the airbags.

What benefits accrue from "drive it like you stole it" -- this is occasionally mentioned in connection with engine performance.

Dennis,

Another 73 - 23 Here and in the possession of an engine guy....

First, Nothing good happens when an engine is idling. Idling is particularly tough on a flat tappet (what you have) engine. Only idle long enough to make it go. The only exception being if you overnighted in a highway rest area. Then, get the temperature gage off the pin before you pull out.

Second, The suspension compressor should run in accessory. If you can't push the cylinder in enough to get there, then the column is broke like mine was and the fix is simple, if you have a lathe, If you don't have access to one, I will send you the shim you need. Johnny and Terry were both right, but as you will be hard pressed to know if the points are closed or not, don't do it. You should also look up a Pertronix 1186. It replaces the points so you don't have to mess with then again - except to put them in a jar and carry as a back up if you are as paranoid as I am. (I know am paranoid about some things, but I am OLD and paranoid.)

Third, Drive it like you stole is pretty much never a good idea, that implies no concern for the hardware. It is a good idea to get to high manifold pressures (lower vacuum) to burn out the carbon from time to time, but that should never happen with the engine cold and while it used to be needed in over-engined passcars, we don't (even with a <10k@ coach) have much trouble that way.

That's my take on that after 40 years of engine development engineering.

Matt

<quote compressed>
> Second, The suspension compressor should run in accessory. If you can't
> push the cylinder in enough to get there, then the column is broke like mine
> was and the fix is simple, if you have a lathe,

> What is this?
--
Gene Fisher -- 74-23,77PB/ore/ca

I may write about this repair for the community, but I have other fires to stomp out just now. When those are down to a smolder, I will document that, the keyless entry, the rear wheel bearing failure and my bolts and gaskets talk that has been a year in the making. All require my time and attention.

Matt