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"Quadrajet was never used on any Chevy 283 engine."
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I wasn't sure on this one, but thought I'd throw it in simply because of it's size for comparison.
Quote
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"Every Chevy Quadrajet ever made uses .029" nozzle bleeds."
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So engine size, (and apparently emissions), never factored in with Chevrolet, interesting. Unless it's because the Chevrolet engines were more efficient than the other GM lines were. The Buick engine was the first to be discontinued, the last one used in '76, followed by Pontiac's 301 I think in '81, and then the Oldsmobile 307 in '89 in the Cadillac Brougham.
Quote
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"All 1968 and later Buick Q-jets uses .054" nozzle bleeds. All earlier uses .029" nozzle bleeds."
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So Buick started this. In '68 I wouldn't think that they were too worried about emissions. Engine size didn't factor in here at all, also interesting.
Quote
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"All 1975 and later Cadillac Q-jets uses .054" nozzle bleeds. All earlier uses .029" nozzle bleeds.
All 1975 and later Olds Q-jets uses .054" nozzle bleeds. All earlier uses .029" nozzle bleeds.
All 1975 and later Pontiac Q.jets uses .054" nozzle bleeds. All earlier uses .047"-.050" nozzle bleeds."
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It's interesting to note that all the rest of GM didn't start using the larger .054" nozzle air bleeds until 1975, but Pontiac was using only slightly smaller ones before '75.
I hadn't ever given them any thought until I began modifications on this 77 Cadillac carb.
Quote
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"If I am using a carburetor that has the extra pull-over tubes in the primary circuit, I remove them and look at the main jetting in the nearest model of the same brand without them and change to this jetting if possible, depending on the size of the main air bleeds."
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When I tried to "copy" a Chevrolet spec with this one I ran into all sorts of issues, which I attribute to the bigger nozzle bleed size, and the removal of the POE tubes.
And yes, a jet size increase helped a bit, and the higher float level improved it somewhat. I haven't gotten around to trying different idle system changes yet.
Today I was making a list of the various drilled set screw sizes that I might need for the different bleeds and restrictions before I start working on it again. I want to have an assortment of them ready so it'll be quicker to make the necessary changes.
