| [GMCnet] Sage Engine Tuning Advice Needed [message #249527] |
Mon, 12 May 2014 16:02 |
glwgmc
Messages: 1014
Registered: June 2004
Karma:
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Senior Member |
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Check to make sure the mechanical advance is working properly in the distributor, check to make sure the small filter in the inlet to the carb is not installed backward or blocked by crud from the lines/tanks, replace the module and coil in the distributor and replace the mechanical fuel pump. All easy and relatively inexpensive things that could be causing those symptoms. If it runs but does not respond to throttle it sounds like either the distributor is not performing electrically as it should or is not advancing with RPMs or the fuel delivery is blocked. The vacuum advance is only there to provide a bit more advance for better economy at high vacuum conditions like flat land cruise. A vacuum leak would normally effect idle and low speed operation more than high RPM applications I would think.
Jerry
Jerry Work
The Dovetail Joint
Fine furniture designed and hand crafted in the 1907 former Masonic Temple building in historic Kerby, OR
Visitors always welcome!
glwork@mac.com
http://jerrywork.com
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Message: 13
Date: Mon, 12 May 2014 11:00:48 -0600
From: George Beckman
Subject: Re: [GMCnet] Sage Engine Tuning Advice Needed
To: gmclist@temp.gmcnet.org
Message-ID:
Content-Type: text/plain; charset="utf-8"
Gary Carlton wrote on Mon, 12 May 2014 09:14
> I have just finished installing a new rebuilt long block 403 into my coach; rebuilt Patterson carb, new fuel pump, distributor cap and wires, etc.
> Got it up and running, no obvious leaks yet, good oil pressure, steady idle, timed to 12 degrees BTDC.
> The issue I am having is that it is low on power under load. Going up hills will lead to slowing down or stalling the engine if more throttle is
> applied.
> I'm guessing a vacuum leak or potentially my distributor vacuum advance has gone wonky but any advice of where you would look first is welcome.
> Thank you in advance
> gary
I agree with the fuel issue. Especially if you can stall it by giving it too much throttle. The open throttle is just letting in too much air and for
some reason the fuel is not flowing. I am guessing that the stall happens when the secondaries start to open.
Fuel pump, filter/s, something wonky in the tanks. Also a crack in a gas hose somewhere between the pump and the tank will break the vacuum and keep
the pump from being able to suck gas. Does switching tanks help?
--
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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Jerry & Sharon Work
78 Royale
Kerby, OR
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