1956 322 idle RPM

[Beemon]

I just recently fired off my 322 Nailhead for the first time since it died in 1978. The shop manual says idle rpm is supposed to be around 350 but when I drop past 500 the car stalls and dies. This seems too low especially with ethanol based gasoline. Any tips?

[Guest smspaul]

Is this a new rebuild or has it been sitting? I believe it is supposed to be 450. If your points and timing are set properly, you should be able to get there.

[Fr. Buick]

350 sounds way too low.  Was that the idle needed to set the timing?  You know, super low so as to not get any advance from the weights? 

 

Relying on memory, my '54 book calls for 450 rpm and the engine seems very happy there, even with the AC on.

 

Are you sure valvetrain is all working?  Pull the valve covers and be sure everything is getting some oil and moving properly.

[Beemon]

My mistake, 450 rpm. Now is that 450 idle in neutral or 450 idle in drive?

The engine was rebuilt. Everything is working great, I primed the oil before ignition and when I was running it, oil pressure was normal. The engine sounds nice, just having trouble dropping the rpms.

Edited June 11, 2015 by Beemon (see edit history)

[avgwarhawk]

I believe 450 is the rpm in neutral.  If I'm correct the rpm needs to be at this range to set timing.  My 264 is happy around 550-600 rpm. 

[old-tank]

New engine:  600 rpm in neutral until worn in when the rpm will creep up;  I like 550-600 to keep the water pump flowing when stuck in traffic.  You can alway turn it down to show off at a cruise-in.

Willie

[Beemon]

Well that's reassuring, it's idling at 600 after using a Dwell meter.

I have a new concern, though. I just had my water pump rebuilt and when I fired the 322 off for the first time it was making an audible ticking noise. I disconnected the belts and ran it for a few seconds and the ticking was gone. I then used a screw driver to my ear and isolated that it was the water pump and not the generator or power steering pump. Is this normal on break in? Sounds like bad bearings which is unfortunate because I had paid for it to be rebuilt.

[NTX5467]

It's probably stalling as there isn't enough air flow (velocity) through the throttle bores of the carb to pull fuel from the float bowl.

On some carburetors, if the base hot idle speed is too low, the sensitivity of the idle mixture adjustment screws will be "soggy". But when that magic rpm is reached, the adjustment can become very sharp and responsive.

From specs I've seen, most stock distributors will not start their centrifugal advance until just over 1000rpm. Not sure about the Nailheads, though. As for the hot base idle speed, I'll agree with Old-Tank on this one . . . a little bit more is not going to hurt anything AND an possibly help things in the operational conditions he mentions. With the slightly higher rpm, the worst thing I can suspect is a little "firmer" transmission engagement into "D" and especially "R". You might need to play with it as it gets more run time and see how everything works for the operational environment you're in.

NTX5467

[TexasJohn55]

My '55 Special book (264) says to lower idle to 350 rpm to adjust timing and then reset to 450 rpm. It also has a timing advance chart for mechanical and vacuum advance at all rpms, Neat.