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#1
10-12-2015, 01:15 PM
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Quadrajet part throttle roughness
I have a 7029263 on a 350 with a summit 2800 cam. 4 speed car. Carb idles nice, great response on acceleration, no hesitation or bog anywhere. Problem is when cruising at low throttle seems to run a little rough. Not real bad and smooths out by touching the pedal. I'm not sure what to address first. Jetting? Float level? Vacuum advance? Any suggestions?
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#2
10-12-2015, 07:25 PM
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It needs a slight recalibration. The manual transmission non Ram Air carbs are leaner than the auto carbs for some reason. We've helped a bunch of them out with similar issues, especially since this new fuel with ethanol came out.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#3
10-13-2015, 06:07 AM
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Thanks. Right now carb has 046 primary rods and 073 jets. What changes would be recommended?
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#4
10-13-2015, 06:14 AM
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I'd recommend a different jet/rod combo. Those carbs have primary POE, so large jets make them too rich at heavy throttle. Contact the shop when you get time and we can discuss a better combo for what you are doing.....Cliff
__________________
If you can read this, thank a teacher. If you can read this in English, thank a Veteran! https://cliffshighperformance.com/ 73 Ventura, SOLD 455, 3740lbs, 11.30's at 120mph, 1977 Pontiac Q-jet, HO intake, HEI, 10" converter, 3.42 gears, DOT's, 7.20's at 96mph and still WAY under the roll bar rule. Best ET to date 7.18 at 97MPH (1/8th mile), |
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#5
10-13-2015, 10:02 AM
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Quote:
Generally (not always), automatic transmission carbs were calibrated richer to compensate for the fluid coupling losses in the transmission. To verify, check the manufacturer's power loss figures for various transmissions. Generally, losses for automatics (at least during this time period) were approximately twice the amount for manuals. The energy for the losses has to be provided, thus the richer carb calibration. Jon.
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"Good carburetion is fuelish hot air".  "The most expensive carburetor is the wrong one given to you by your neighbor". If you truly believe that "one size fits all" try walking a mile in your spouse's shoes! Owner of The Carburetor Shop, LLC (of Missouri). Current caretaker of the remains of Stromberg Caburetor, and custodian of the existing Carter and Kingston carburetor drawings. |
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