| [GMCnet] Engine misses on acceleration [message #343412] |
Fri, 17 May 2019 08:24  |
glwgmc
Messages: 1014
Registered: June 2004
Karma: 10
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Senior Member |
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Check the advance weights in the distributor. If they are stiff or frozen your timing can be correct at idle but way off while driving. With that many miles check the timing chain. It may have stretched to the point the cam timing is way off also. Pull the fuel pump and you can check the timing chain for slack.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
glwork@mac.com
http://jerrywork.com
===============
Message: 11
Date: Fri, 17 May 2019 04:05:26 -0600
From: Cary Lawson
To: gmclist@list.gmcnet.org
Subject: [GMCnet] Engine misses on acceleration
Message-ID:
Content-Type: text/plain; charset="utf-8"
I bought my 1975 Glenbrook about 2 years ago and have been working on it off and on.
The coach has always had poor acceleration and a very heavy thud-thud-thud when accelerating.
However the engine idles very smoothly.
Olds 455 with carb and HEI ignition.
It has 150,000 miles but the compression checks fairly well, most between 160 to 170 with one cylinder at 150.
The Rochester carb has been rebuilt
New plugs, cap, and rotor
Timing reset
New fuel filters through out
New mechanical fuel pump
The wires show no signs of leakage or sparking in the dark but I am thinking to replace them as a next step.
Also the vacuum lines have been replaced as needed but I am planning to replace all to eliminate that.
The vacuum advance moves but takes a lot of force to nudge it with a screwdriver. Should it be that stiff?
I would appreciate any and all suggestions to diagnose.
thanks! Cary
Cary Lawson
1975 Glenbrook, 455, carb, HEI
Wellington, Ohio
--
Cary Lawson
75 Glenbrook
Cleveland, Ohio
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Jerry & Sharon Work
78 Royale
Kerby, OR
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| Re: [GMCnet] Engine misses on acceleration [message #343413 is a reply to message #343412] |
Fri, 17 May 2019 08:45  |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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Not that this is the issue, but be sure to gap the plugs at .40 not any
more.
On Fri, May 17, 2019 at 6:25 AM Gerald Work via Gmclist <
gmclist@list.gmcnet.org> wrote:
> Check the advance weights in the distributor. If they are stiff or frozen
> your timing can be correct at idle but way off while driving. With that
> many miles check the timing chain. It may have stretched to the point the
> cam timing is way off also. Pull the fuel pump and you can check the
> timing chain for slack.
>
> Jerry
> Jerry Work
> The Dovetail Joint
> Fine furniture designed and hand crafted in the 1907 former Masonic Temple
> building in historic Kerby, OR
>
> glwork@mac.com
> http://jerrywork.com
> ===============
> Message: 11
> Date: Fri, 17 May 2019 04:05:26 -0600
> From: Cary Lawson
> To: gmclist@list.gmcnet.org
> Subject: [GMCnet] Engine misses on acceleration
> Message-ID:
> Content-Type: text/plain; charset="utf-8"
>
> I bought my 1975 Glenbrook about 2 years ago and have been working on it
> off and on.
> The coach has always had poor acceleration and a very heavy thud-thud-thud
> when accelerating.
> However the engine idles very smoothly.
>
> Olds 455 with carb and HEI ignition.
> It has 150,000 miles but the compression checks fairly well, most between
> 160 to 170 with one cylinder at 150.
>
> The Rochester carb has been rebuilt
> New plugs, cap, and rotor
> Timing reset
> New fuel filters through out
> New mechanical fuel pump
>
> The wires show no signs of leakage or sparking in the dark but I am
> thinking to replace them as a next step.
>
> Also the vacuum lines have been replaced as needed but I am planning to
> replace all to eliminate that.
>
> The vacuum advance moves but takes a lot of force to nudge it with a
> screwdriver. Should it be that stiff?
>
> I would appreciate any and all suggestions to diagnose.
> thanks! Cary
>
> Cary Lawson
> 1975 Glenbrook, 455, carb, HEI
> Wellington, Ohio
>
> --
> Cary Lawson
> 75 Glenbrook
> Cleveland, Ohio
> =================
>
>
>
>
>
>
>
>
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> GMCnet mailing list
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--
Jim Kanomata
Applied/GMC, Newark,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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