Fast idle delete ?
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
Fast idle delete ?
Why do I need my car to do a high fast idle on startup for a minute or two ? Couldn't I just adjust the choke so I start on "medium" idle and wait a
little longer ? Having a car start cold and idle so high seems contradictory to me. I thought you should not "rev" an engine till warm.....just curious because right now my idle is set lower and seems fine if not a little rich when stone cold.
little longer ? Having a car start cold and idle so high seems contradictory to me. I thought you should not "rev" an engine till warm.....just curious because right now my idle is set lower and seems fine if not a little rich when stone cold.
Team Owner
Joined: Sep 2006
Posts: 31,270
Likes: 4,362
From: Westminster Maryland
Hi BN,
I Don't know.
Is there some advantage to the oiling system to have the fast idle, and perhaps some advantage to bringing the engine to operating temperture quickly?
???
Regards,
Alan
I Don't know.
Is there some advantage to the oiling system to have the fast idle, and perhaps some advantage to bringing the engine to operating temperture quickly?
???
Regards,
Alan
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
My race engine background (limited admittedly ) tells me high RPMS at cold idle is not good. Better to wait til warm ? I have been wondering if a diesel engine block warmer is not a bad option. I have my car set up for performance and it suffers at idle so maybe it's not a bad idea. Mind you I have not done even basic research into block warmers.....seems like it would be much less wear on engine parts than high idle....
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
It just kinda reminds me of some guy you hear get in his car when it's stone cold and rev the thing a bunch for whatever reason he thinks he has. Warm up, sound mean whatever. I thought it was best to be cool until that girl was ready. Maybe I'm wrong ?
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Safety Car
Joined: Jun 2004
Posts: 4,371
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From: Beecher Illinois
I have the fast idle adjusted much lower than factory on all my Vettes. Just turn it down.
Also I adjusted the chokes. At the time I did this the outside temp was about 50 degrees out. With the motor cold I turned the choke housing with the thermostatic spring inside to where the choke JUST closed.
Before it was kinda beyond closed, where it had to warm up a bit before it even started to open.
Besides, I never drive em when it's real cold out.
Also I adjusted the chokes. At the time I did this the outside temp was about 50 degrees out. With the motor cold I turned the choke housing with the thermostatic spring inside to where the choke JUST closed.
Before it was kinda beyond closed, where it had to warm up a bit before it even started to open.
Besides, I never drive em when it's real cold out.
Race Director
Joined: Jul 2001
Posts: 15,892
Likes: 42
50ish years of manufacturing SBCs taught GM that they're not fragile pieces of glass that shatter if someone f*rts. They were built to be cold started at minus whatever degrees, be tossed immediately into gear and driven for 150K miles in between overhauls with a minimum of care and maintenance. I think they got it right.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
50ish years of manufacturing SBCs taught GM that they're not fragile pieces of glass that shatter if someone f*rts. They were built to be cold started at minus whatever degrees, be tossed immediately into gear and driven for 150K miles in between overhauls with a minimum of care and maintenance. I think they got it right.
Thread Starter
Drifting
Joined: Mar 2011
Posts: 1,271
Likes: 1
From: PA
I have the fast idle adjusted much lower than factory on all my Vettes. Just turn it down.
Also I adjusted the chokes. At the time I did this the outside temp was about 50 degrees out. With the motor cold I turned the choke housing with the thermostatic spring inside to where the choke JUST closed.
Before it was kinda beyond closed, where it had to warm up a bit before it even started to open.
Besides, I never drive em when it's real cold out.
Also I adjusted the chokes. At the time I did this the outside temp was about 50 degrees out. With the motor cold I turned the choke housing with the thermostatic spring inside to where the choke JUST closed.
Before it was kinda beyond closed, where it had to warm up a bit before it even started to open.
Besides, I never drive em when it's real cold out.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
Ok. I hear ya. I guess just false concerns. I've never really played with a stock setup. The first thing I always did was pull all the gizmos off and try to go faster at all costs.....while pondering the OE setup it just seems excessive to idle that high when cold. Or was that just an engineering compromise to make the driving experience easier for the consumer ? Compromises are made all the time.
My new FI computer controlled engine idles at 650 rpm after starting in all kinds of weather. It took computer engine management to finally get it right.
In S Florida, I have the butterfly adjusted wide open, cold (no choke), starts with 2 pumps and has to be feathered a bit for 15 seconds and then will idle at 800 rpm in neutral. Usually wait 5 minutes before driving.
I don't like the factory set choke on high idle either.
IMO, block heaters are always good, as are accumulators, but I don't bother with them. If it was a Maybach, then maybe.
Drifting
Joined: Mar 2011
Posts: 1,886
Likes: 9
50ish years of manufacturing SBCs taught GM that they're not fragile pieces of glass that shatter if someone f*rts. They were built to be cold started at minus whatever degrees, be tossed immediately into gear and driven for 150K miles in between overhauls with a minimum of care and maintenance. I think they got it right.
I adjust my 74 small block to factory spec. I can start it in 20 degree weather and drive it right away. I "balloon foot" it till it is fully warm. Remember, any time you are idling, you are getting 0 miles per gallon.
Actually, due to the inefficiency of a cold engine, a cold idle speed, correctly adjusted, is just about the same as a warm idle speed, anyway.
If the stock fast idle setting seems too high for your car, shave it 100 RPM at a time untill you are happy.
Last edited by gcusmano74; Oct 27, 2011 at 02:58 PM.
Le Mans Master
Joined: Mar 2008
Posts: 5,948
Likes: 72
From: Oxford MA-----You just lost the game!!!!
Most of the carb books that I have read give a theory that the high initial idle speed increases oil pressure while cold, and gets a little more airflow thru the carb in order to help vaporization while cold. I like to set my high idle around 1200-1300 rpm, I don't think that will harm the engine much more than idleing at 700-900 while cold. Just don't zing it up to 6 grand before it can even get oil sucked up into the pump!!!!
Scott
Scott
