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 Question about enlarged secondary well mod 
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Joined: Fri Oct 23, 2015 8:43 am
Posts: 33
Am I correct in thinking that a bigger secondary main well will only make the A/F go richer on initial opening of the secondary throttle plates (acting as a bit of a "pump shot"). Once you are running steady-state WOT, wouldn't the metering rod / .0135 pressed in secondary jet and air bleed tube determine the fuel curve regardless of secondary main well size (leaving the cap jet out of the discussion for the moment, as obviously that circuit influences fuel curve too).


Wed Sep 07, 2016 3:44 pm
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1744
That's the way it acts as I see it. There are some OE QJets with a larger well than the common ~.200", Pontiac I recall.

I was thinking about two things when I first started dong the secondary modification of turning the tube upside-down to locate the .026" bleed at the top, drilling four .025" bleed holes in the lower end, and drilling the well to #1. One, was the added well volume for tip-in enrichment, and two, the bubbles from the four .025" holes need some room to move up the well. I can tell you the few times I tried .250" for the well it made it too rich.

I haven't tried a standard .200" well with the bleed tube upside-down and the four bleeds at the lower end. If one of you guys try that, let us know how it worked.

Wed Sep 07, 2016 5:23 pm

Joined: Wed Oct 23, 2013 8:01 am
Posts: 113
The last one I did I drilled the wells to .209 or .213, can't remember I didn't write it down & it still seemed plenty rich.

Thu Sep 08, 2016 8:25 am
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