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| | | | Joined: May 2004 Posts: 920 'Bolter | | 'Bolter Joined: May 2004 Posts: 920 | Just curious about what rpms you guys are experiencing at warmed up idle. I seem to be able to get mine to idle pretty smoothly at 600 rpm. Could I, or should I try to get lower? Higher? | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | You might want to indicate the make, year, truck-model, and size-engine? | | | | | Joined: Dec 2008 Posts: 1,922 'Bolter | | 'Bolter Joined: Dec 2008 Posts: 1,922 | How is your oil pressure at 600? Does raising it 100 increase the pressure? | | | | | Joined: Apr 2007 Posts: 1,038 'Bolter | | 'Bolter Joined: Apr 2007 Posts: 1,038 | Looking at the '47-51 truck shop manual, they say to set the idle at 400-450 rpm, for both the Carter and Rochester carbs. I confess I set mine by ear.
Kent | | | | | Joined: Jul 2000 Posts: 2,192 Insomniac | | Insomniac Joined: Jul 2000 Posts: 2,192 | I prefer 600 rpm for the following reasons:
At 450 rpm the ammeter reads on the "D" side even with the lights off. At 600 it seems the generator is turning fast enough to maintain charge. This probably won't be an issue if I had an alternator.
Where I live here in the Pacific Northwest, we often have outside temperatures that are close to the dew point. This can lead to carb ice. Carb ice can happen when the engine is warmed up and the choke is fully open. A slightly faster idle helps to avoid stalling when you are at a traffic light with your foot on the brake pedal. I don't have a throttle cable; if I had one I would use it.
I have not had any problem with "run on" or "dieseling" with the idle speed set at 600.
Gord 🇨🇦
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1954 1/2 ton 235 4 speed
| | | | | Joined: May 2004 Posts: 920 'Bolter | | 'Bolter Joined: May 2004 Posts: 920 | 261 stroker. Dual carbs, Dual exhaust, HEI | | | | | Joined: Feb 2004 Posts: 29,792 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,792 | It's pretty unlikely you'll be able to get a twin carb rig to idle slower without creating a bog when you try to take off from a stop. You can completely ignore the factory specs on that rig- - - - -way too many modifications. Just shoot for a smooth takeoff without Dieseling on shutdown. Camshaft profile and manifold vacuum will make a huge difference on idle speed, also.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
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