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Old 11-21-2012, 01:12 PM   #21 (permalink)
 
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rough idle

Yes- I mixed and matched needles & seats- kept new needles, changed needle springs. Neither needle sticks- even after about 100 blow-throughs. Raised the floats a hair- were at 9/64- put 'em at 5/64- didn't look like enough gas was getting into the accelerator pump chamber. I fully intend to speak to Lars- I just need to break down and purchase vac. gauges, dial back timing light, etc... another couple a hundred for a one time use only deal. I realize it's necessary,but this is the last vehicle I'll ever work on.After this one, it's over. ..... but out of the 40 some auto's I've had, I've only experienced this tuning plague 3 times-Twice with this car (326, 455), once w/ an old Chevy in 1990- had a plugged catalytic converter. Course, never had a Pontiac before, either. The thrill is all but gone.
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Old 11-21-2012, 02:07 PM   #22 (permalink)
 
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One more thing to check....

Many carbs don't handle fuel pressures above about 5 psi. Some of the mechanical fuel pumps will put out over 6 psi and that might be enough to overcome the needle seat pressure, dumping too much fuel into the float bowls.

If your fuel pressure is too high, you'll need to either change the pump or add a fuel pressure regulator.
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Old 11-21-2012, 04:34 PM   #23 (permalink)
 
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rough idle

Thanks, jmt455- I'll check that deal, also- new pump, but I pulled it from 326. Don't know if there's any difference to speak of.
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