PV cold fast idle speed 66 327/300hp

[Dave K.]

Has anyone gone through PV recently on their 66 327/300 hp engine? What cold fast idle speed will the Team Leader be looking for? Reason that I ask is that at the National last year during flight judging the outside air temp was 85F and my car started and the fast idle was 800 RPM. OPS judge wanted at least 1000 RPM even though the ambient air temp was 85F.

Regards,
Dave K.

[Michael W.]

Re: PV cold fast idle speed 66 327/300hp

Calling Mike Hanson............

[William C.]

Re: PV cold fast idle speed 66 327/300hp

Dave if the Choke is fully closed, (which it should be @ 85 degree ambient) it will raise the fast idle cam to the top step if properly adjusted, The engine starts and the vacuum break opens the choke blade but the fast idle cam remains at the top step until the throttle is opened via the throttle linkage. Properly adjusted with the fast idle cam on the top step, it will take some time as the engine warms up, but the actual spec for idle speed on the top step of the cam is 2000-2200 on a hot engine. Check to see that with the choke closed you are adjusted to hit the top step on the cam, and that the choke pull-off is adjusted properly. Start it and just watch, as it warms up you will think the engine is coming out of the car. 1000 is a gift!

[Duke W.]

Re: PV cold fast idle speed 66 327/300hp

Look at your CSM. There should be a spec for the fast idle, which is normally set with the engine at normal operating temperature. For earlier 327/300s with AFBs it is 1750, hot. This would result in an initial cold idle of about 1500.

Even at 85 degrees when you pump the pedal the choke should fully close, which also sets the fast idle cam at the same point as if you cold started at lower temperature.

You need to be sure that the choke is fully closing and the various links are properly adjusted along with the fast idle speed screw. All this info should be in the CSM.

Duke

[Clem Z.]

Re: PV cold fast idle speed 66 327/300hp

why don't they just do like the manual says, warm up the engine to operating temp,shut it off,close the choke plate by hand to set the fast idle cam and restart the engine and then check the RPMs to see if it matches the shop manual ?? this to me would solve all these what should the idle be questions. JMHO

[William C.]

Re: PV cold fast idle speed 66 327/300hp

Because the cold function is what is being checked, not the ultimate hot fast idle speed.

[Clem Z.]

Re: PV cold fast idle speed 66 327/300hp

Because the cold function is what is being checked, not the ultimate hot fast idle speed.

where are these specs listed in the GM lit. ??? if the ultimate fast idle speed is correct all the adjustments are correct and there is nothing to be done about the other speeds as they would be just a guess. these speeds would depend on the oil viscosity, the piston to wall clearance,ring tension,timing and the valve settings.

[Dave K.]

Re: PV cold fast idle speed 66 327/300hp

Clem,

Duke and Clupp are referring to the 1966 Chevrolet Service Manual. There are specs in there for hot fast idle RPM and hot normal idle RPM. By the way, the Holley 4160, list 3360 carb has a tang that must be bent and not a screw to adjust the RPM when on the high speed carb cam. This whole area has to be one of the most confusing areas of OPS and PV testing that there is!

Dave K.
Chairman, Pa. Regional 2012

[Clem Z.]

Re: PV cold fast idle speed 66 327/300hp

Clem,

Duke and Clupp are referring to the 1966 Chevrolet Service Manual. There are specs in there for hot fast idle RPM and hot normal idle RPM. By the way, the Holley 4160, list 3360 carb has a tang that must be bent and not a screw to adjust the RPM when on the high speed carb cam. This whole area has to be one of the most confusing areas of OPS and PV testing that there is!

Dave K.
Chairman, Pa. Regional 2012

you are correct as the only specs i have ever seen are idle speed with the fast idle cam on the top step with the engine fully warmed up and the curb idle speed when fully warmed up and completely off of the fast idle cam and choke. i have no idea what you would set for a idle speed in between those 2 parameters.

[Tim E.]

Re: PV cold fast idle speed 66 327/300hp

Dave - The fast idle spec in the PV manual for a '66 327/300 is 1500-1800 RPM. There is another sentence that says "Warm air temperatures and/or high altitudes may cause a fast idle speed in the range of 1100-1400 RPM".

I struggled with this very thing on my '66 327/300 and failed a PV attempt because of this on a 96 degree day with the car outside in full sun. After using my fix to adjust the fast idle linkage to it's mechanical limits, the car still wouldn't get over 1100 RPM.

The judges will be looking for 1500-1800 regardless of outside air temperature and regardless of the warm air temperature sentence.

Good luck, you'll get it! Tim

[Clem Z.]

Re: PV cold fast idle speed 66 327/300hp

Dave - The fast idle spec in the PV manual for a '66 327/300 is 1500-1800 RPM. There is another sentence that says "Warm air temperatures and/or high altitudes may cause a fast idle speed in the range of 1100-1400 RPM".

I struggled with this very thing on my '66 327/300 and failed a PV attempt because of this on a 96 degree day with the car outside in full sun. After using my fix to adjust the fast idle linkage to it's mechanical limits, the car still wouldn't get over 1100 RPM.

The judges will be looking for 1500-1800 regardless of outside air temperature and regardless of the warm air temperature sentence.

Good luck, you'll get it! Tim

if the fast idle speed is set with a warmed up engine to the RPM stated in the shop manual you should have the correct GM required start up idle speed no matter what the conditions. i am sure GM spend a lot of engineering time coming up with these specs

[Dave K.]

Re: PV cold fast idle speed 66 327/300hp

Tim,

I was at the San Antonio National several years ago and watched a 66 big block car be PV tested. The outside air temp was 90F. Do you know that the Team Leader made the owner get dry ice and pack it around the carb and intake manifold in an attempt to get a higher fast idle speed. The faster the ice was applied the more fog and smoke it made. Clem Z. suggested that I have a cooler filled with dry ice.

Good to hear from you,

Dave K.

[William C.]

Re: PV cold fast idle speed 66 327/300hp

Tim if the choke is full closed, fast idle upon start in warm temps will be higher not lower if you follow the factory starting procedure. Choke should be FULL Closed at startup at revirtually any (I think 100%) temperature. The procedure is hit the pedal once to set the choke, LET OFF THE Accellerator pedal, then crank the car until it starts. DO NOT TOUCH the throttle pedal. The engine will start, and as the choke opens, the throttle will be held open by the plastic cam and the RPM will rise to a speed that will scare you! I used to do "railhead" audits for GM occasionally, and we went in both the hottest and coldest parts of the country. Never had one that did not act as I have described, even in Phoenix AZ summer. Most of the "cold idle" failures I have observed were owners who did not follow this procedure in EXACT detail, as described in the least read book in the world, the owners manual.

[Michael H.]

Re: PV cold fast idle speed 66 327/300hp

Calling Mike Hanson............

You mean this one from 2004?

https://www.forums.ncrs.org/showthre...ighlight=choke

[Michael W.]

Re: PV cold fast idle speed 66 327/300hp

You mean this one from 2004?

https://www.forums.ncrs.org/showthre...ighlight=choke

That's the one. That's from 2004- eight years ago already.