Cliff's Quadrajet Parts and Rebuild Kits
Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: billy 2 on May 31, 2010, 12:30:24 PM
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I am helping a friend with his quadrajet carburetor and it seems as though it runs rich at idle. It's a stock 7028213. The engine is a small block Chevy, pretty stock except for the cam that is a 350/350 hp. It seems to run well off idle and at cruise speed. The idle mixture screws are only about 1/2 turn out with 13 pounds of vacuum. Any thoughts about how to get the idle to run a little leaner? billy2
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More engine details?
What is the static compression ratio.
What cylinder head castings are used?
What is the CID of the engine?.....Cliff
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Compression ratio 81/2 to 9to1
cylinder heads' casting number 993's 76cc 1972-73 truck head
350 bored 30 over
cam shaft is a GM 327 350 hp
He thought the lift was .347
Air fuel mixture screws are set 1/2 turn out and getting the best vacuum there at 13 pounds
It smells rich and spark plugs look wet
Thanks billy 2
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Pretty big camshaft for the low compression 350 engine.
That particular cam has a LOT off off seat duration, overlap, and wide LSA. Very good camshaft, but it likes 10 to 1 or higher compression for best results.
I would set up the carburetor to "recipe" # 3 in our book for the idle system.
For the main system it shouldn't be too far off, check the main airbleed sizes, they should be around .050" for both pairs. What jets and metering rods are being used?.....Cliff
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Cliff The jets are 71's and the rods are 43's. WE used one of your rebuild kits with all the good parts Thanks. billy 2