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Old 07-18-2008, 03:52 PM
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Originally Posted by oldbogie
You used a term that got my attention which is "secondary jets go dry"! If the jets were to go dry you'd have a serious leaning of the mixture, either a top end back fire and or detonation would be the first indicators, roasted pistons would be next. The Holley (actually any carb in drag racing) does have a situation from vehicle dynamics where the fuel rushes toward the primary jets and away from the secondary jets. The secondary jets typically being larger will show a greater amount of leaning than the smaller primaries will show richening. This is where jet extensions can be of help, especially on the secondaries because the fuel rushing away from the jets can cause a severe lean drop in the mixture. With jet extensions it keeps the jet connected with the pool of fuel now at the rear of the float bowl. On the primary side I like a bit shorter jet extension to average out the depth of fuel that is now a puddle against the metering block, although, I'm a lot less concerned about the primary side as possible engine destruction isn't an issue here, this is just a tuning issue to keep the mixture in a tight range around what works best for the engine.

I don't think the secondary jets are going dry. The only reason I asked is because F-Bird88 mentioned the extensions. I have no reason to believe this is a problem at this time.

I certainly have no problem changing jets. Carb tuning isn't new to me; I was just curious about that one question and the removeable air bleeds which are new to me. It seems to me I could've answered this question by just going out and doing it.

I appreciate the replies; I think it's time for less conversation, more action

81 Grand Prix, 355, 700r4, 8.5" 4.10
64 Oldsmobile Jetstar, all original
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