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Old 11-28-2020, 12:41 PM   #30
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Join Date: May 2010
Location: East Shore of LAKE HOUSTON
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Default Re: “Inside” part of road draft tube

Originally Posted by Norris McCarty View Post
I can be dangerous and screw up a lot of parts given too much time to think!!!!!
Well, me too, but here are MY thoughts anyway! First of all, WHY are 'we' using a neat old Navarro 3-carburetor manifold....with the two end positions blocked-off? None of my business, but just curious, especially if you are going to start irreversibly cutting on that web between the two bores. You could easily accomplish the same result with a little whittling on one THICK plate, or with two stacked plates, with the bottom one whittled-out over that center web.

Secondly, in my opinion (and WTF do I know), if you leave your vacuum source fitting in the position shown, that front, right cylinder is likely to do the majority of the sucking, leaner than about all of the others. Air is like real thin follows the path of least resistance. To prevent any more unbalance in the mixture than necessary, that vacuum fitting needs to be pretty much centralized in the grand scheme of things. End cylinders (especially with ONE carburetor) always tend to run leaner as it is. I BELIEVE you'd be better off designing a plate (spacer, maybe) to go under that center carb, configured such that it draws from the center of both plenums equally. That's the best 'mix' you're going to accomplish as far as even distribution of what amounts to a tiny vacuum leak. But again, what do I know? DD

PS......Don't forget (if you read my thread on our PCV project) that MOST PCV valves are designed to operate in a vertical orientation..........just sayin'!

"There are only THREE kinds of people. Those who understand math, and those who don't..."
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