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Old 10-12-2010, 09:43 PM   #15
motornut
78K & 79C Jimmys
 
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Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
Re: QJet Adjustments

I second that,
and have made some temp linkages outa cut up bits of metal cloths hangers
Quote:
Originally Posted by ray_mcavoy View Post
Yeah, get that linkage and hook it back up. Sounds like the PO wan't very familiar with how QJets work.

They have mechanical secondary throttle blades with a set of "air doors" on top. The air doors open based on engine demand (the air flowing past them pulls them open). That vacuum can & linkage that the PO removed doesn't actually open the secondary air doors. Instead, it acts as a damper to keep them from opening too quickly. There's also a torsion spring that controls the opening rate.

The bog you're getting is a sure sign that the secondary air doors are opening too quickly because of the missing parts. The air doors also operate the secondary metering rods that irishman999 mentioned. With the missing parts, the air doors are likely opening too far (beyond engine demand) and in turn, pulling the secondary rods to the max rich position.
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1978 GMCJimmy4X4-350/203
1979 GMCJimmy4X2-305/350
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