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455 idle speed [message #301675]

Mon, 06 June 2016 10:54

Bob S.

Messages: 143
Registered: October 2012
Location: Rapid City, SD

Karma: 2

Senior Member

I recently installed the FItech EFI on my 455 and so far have been happy with it. I am trying to get it dialed in and for the life of me, I can not find the recommended idle speed for a 455. I have looked in the Maintenance manuals and searched here on the forum and it remains elusive. I'm sure it is in the MM somewhere but I'll be darned if I could find it. My last resort is to bother the Brain Trust here for the answer. As I stated I am looking for the recommend RPM for idle both in neutral and in gear. Any and all help is greatly appreciated.

Bob and Pam Schilling Rapid City, SD "78 Royale

[Updated on: Mon, 06 June 2016 10:55]

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Re: 455 idle speed [message #301679 is a reply to message #301675]

Mon, 06 June 2016 11:26

A Hamilto

Messages: 4508
Registered: April 2011

Karma: 39

Senior Member

Bob S. wrote on Mon, 06 June 2016 10:54

I recently installed the FItech EFI on my 455 and so far have been happy with it. I am trying to get it dialed in and for the life of me, I can not find the recommended idle speed for a 455. I have looked in the Maintenance manuals and searched here on the forum and it remains elusive. I'm sure it is in the MM somewhere but I'll be darned if I could find it. My last resort is to bother the Brain Trust here for the answer. As I stated I am looking for the recommend RPM for idle both in neutral and in gear. Any and all help is greatly appreciated.

My Maintenance Manual says set it according to the label on the rocker arm cover (long gone) Set it between 500 and 600 RPMs. Too fast and the transmission is pulling while stopped at traffic lights raising the coolant temperature. Too low and it will want to die when the AC compressor kicks on idling at a traffic light.

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Re: [GMCnet] 455 idle speed [message #301680 is a reply to message #301675]

Sun, 05 June 2016 20:25

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

650 RPM in Drive

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of Bob Schilling
Sent: Tuesday, June 07, 2016 1:55 AM
To: gmclist@list.gmcnet.org
Subject: [GMCnet] 455 idle speed

I recently installed the FItech EFI on my 455 and so far have been happy with it. I am trying to get it dialed in and for the life
of me, I can not
find the recommended idle speed for a 455. I have looked in the Maintenance manuals and searched hear on the forum and it remain
elusive. I'm sure it
is in the MM somewhere but I'll be darned if I could find it. My last resort is to bother the Brain Trust here for the answer. As I
stated I am
looking for the recommend RPM for idle both in neutral and in gear. Any and all help is greatly appreciated.
--
Bob and Pam Schilling
Rapid City, SD
"78 Royale

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Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: 455 idle speed [message #301684 is a reply to message #301675]

Mon, 06 June 2016 11:32

Jon payne

Messages: 495
Registered: May 2008

Karma: 1

Senior Member

Per the GMC maintenance manual, under carburetor adjustments, with the engine at normal operating temperature, timing properly set, transmission in drive, the idle should adjusted to 600 RPM.

Jon

Jon Payne
76 Palm Beach
Westfield,IN

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Re: [GMCnet] 455 idle speed [message #301687 is a reply to message #301675]

Mon, 06 June 2016 11:20

emerystora

Messages: 4442
Registered: January 2004

Karma: 13

Senior Member

I run mine at about 800-900 rpm.

Maintenance Manual X7725 for 77-78 GMC
see pages 6m-16, 6m-17 and specs on 6y-33 and 6y-34.

Emery Stora
77 Kingsley
Frederick,
CO

> On Jun 6, 2016, at 9:54 AM, Bob Schilling wrote:
>
> I recently installed the FItech EFI on my 455 and so far have been happy with it. I am trying to get it dialed in and for the life of me, I can not
> find the recommended idle speed for a 455. I have looked in the Maintenance manuals and searched hear on the forum and it remain elusive. I'm sure it
> is in the MM somewhere but I'll be darned if I could find it. My last resort is to bother the Brain Trust here for the answer. As I stated I am
> looking for the recommend RPM for idle both in neutral and in gear. Any and all help is greatly appreciated.
> --
> Bob and Pam Schilling
> Rapid City, SD
> "78 Royale
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

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Re: [GMCnet] 455 idle speed [message #301688 is a reply to message #301687]

Mon, 06 June 2016 12:27

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

Senior Member

I would say it kinda depends. On which cam you have in the engine, on where
you set your base timing with the fuel injection, on which torque converter
you have in the transmission, and several other variables. Over 500 and
under 900 ought to be close enough. The manual is going to give you a speed
based on 1973-1978 gasoline and conditions on a bone stock brand new
condition GMC. Does that still apply in your case?
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jun 6, 2016 10:21 AM, "Emery Stora" wrote:

> I run mine at about 800-900 rpm.
>
> Maintenance Manual X7725 for 77-78 GMC
> see pages 6m-16, 6m-17 and specs on 6y-33 and 6y-34.
>
> Emery Stora
> 77 Kingsley
> Frederick,
> CO
>
>> On Jun 6, 2016, at 9:54 AM, Bob Schilling
> wrote:
>>
>> I recently installed the FItech EFI on my 455 and so far have been happy
> with it. I am trying to get it dialed in and for the life of me, I can not
>> find the recommended idle speed for a 455. I have looked in the
> Maintenance manuals and searched hear on the forum and it remain elusive.
> I'm sure it
>> is in the MM somewhere but I'll be darned if I could find it. My last
> resort is to bother the Brain Trust here for the answer. As I stated I am
>> looking for the recommend RPM for idle both in neutral and in gear. Any
> and all help is greatly appreciated.
>> --
>> Bob and Pam Schilling
>> Rapid City, SD
>> "78 Royale
>>
>>
>> _______________________________________________
>> GMCnet mailing list
>> Unsubscribe or Change List Options:
>> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
>
> _______________________________________________
> GMCnet mailing list
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>
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Re: 455 idle speed [message #301697 is a reply to message #301675]

Mon, 06 June 2016 16:25

Bob S.

Messages: 143
Registered: October 2012
Location: Rapid City, SD

Karma: 2

Senior Member

Thanks to all for the information. I had a little trouble with stalling at stops(intermittently) so I bumped up the idle to 750 in park. That drops to about 650 in Drive. A test drive yesterday, after the adjustment, went well with no stalling. I think I'll leave it where it is unless I run into more problems. Thanks again to everyone for you time.

Bob and Pam Schilling Rapid City, SD "78 Royale

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Re: [GMCnet] 455 idle speed [message #301704 is a reply to message #301697]

Mon, 06 June 2016 01:44

USAussie

Messages: 15912
Registered: July 2007
Location: Sydney, Australia

Karma: 6

Senior Member

Bob,

As long as it doesn't diesel when you shut it down you're good to go! If it does FIX it, Double Trouble backfired when it was
dieseling and split a brand new muffler open at the seam!

Regards,
Rob M.
USAussie - Downunder
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426

-----Original Message-----
From: Bob Schilling

Thanks to all for the information. I had a little trouble with stalling at stops(intermittently) so I bumped up the idle to 750 in
park. That drops to about 650 in Drive. A test drive yesterday, after the adjustment, went well with no stalling. I think I'll leave
it where it is unless I run into more problems. Thanks again to everyone for you time.
--
Bob

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GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

Regards, Rob M. (USAussie) The Pedantic Mechanic Sydney, Australia '75 Avion - AUS - The Blue Streak TZE365V100428 '75 Avion - USA - Double Trouble TZE365V100426

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Re: 455 idle speed [message #301731 is a reply to message #301675]

Mon, 06 June 2016 20:44

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

Senior Member

I'm guessing this EFI doesnt have a P/N input. So then set it like the carb. If it does, it will add RPM in gear and remove it in P/N, so your base P/N speed can be about 50 lower as it will add 50 in gear.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: [GMCnet] 455 idle speed [message #301776 is a reply to message #301731]

Tue, 07 June 2016 10:30

mark grady

Messages: 70
Registered: November 2015
Location: northern Indiana

Karma: 0

Member

Also note that there is a lead on the FiTech for an idle speed increase
when the AC compressor engages. I would use a cube relay to prevent the A6
compressor from inducing voltage back into the FiTech.

I haven't done my install yet and some engineering would be needed, but
this looked like a nice feature of the FiTech system.

On Mon, Jun 6, 2016 at 9:44 PM, John R. Lebetski
wrote:

> I'm guessing this EFI doesnt have a P/N input. So then set it like the
> carb. If it does, it will add RPM in gear and remove it in P/N, so your
> base
> P/N speed can be about 50 lower as it will add 50 in gear.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
> Source America First
>
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'77 + 78 Kingsley

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Re: 455 idle speed [message #301789 is a reply to message #301675]

Tue, 07 June 2016 11:56

RF_Burns

Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada

Karma: 3

Senior Member

Rob,
With EFI the fuel stops immediately when you shut down... no fuel to diesel on with, or collect in your muffler to backfire! And no fuel left in the cylinders to wash down the cylinders and dilute the oil.

EBL has an input from the A/C to bump up idle as well as P/N and Drive idle idle tables. There is an Aux idle control that can be used to increase the idle speed if you have a need for that. I don't know that anyone has used the A/C or Aux idle controls.

Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that

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