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#1
12-08-2013, 02:57 PM
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389 accelleration on throttle hiccup
Hello, just joined up! I have had my 1971 GTO with a 1964 Bonneville 389 in it for 20 years.
For a while my 389 has been hiccuping once on acceleration off steady low throttle-- then it pulls great. the accelerator pump seem to be working ok. Has anyone ever experienced this? thanks , JK |
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#2
12-08-2013, 07:51 PM
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Welcome aboard!
Does this have the Carter AFB or AVS style carb on it still? Have you checked the timing and advance curve to make sure the advance weights aren't stuck? An easy thing to check would be the power valves. They are located under the small steel plates[one on each side, near the end of the choke valve], held in by a single hex head screw. These have a spring under them so they should pop up when the steel plate is removed. If not, they are stuck and that could be your issue. Engine manifold vacuum holds them down, and when you give it gas, manifold vacuum goes away and the spring pushes the power valve up, which pulls the metering rods out of the jets.
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Paul Carter Carter Cryogenics www.cartercryo.com 520-409-7236 Koerner Racing Engines You killed it, We build it! 520-294-5758 64 GTO, under re-construction, 412 CID, also under construction. 87 S-10 Pickup, 321,000 miles 99Monte Carlo, 293,000 miles 86 Bronco, 218,000 miles |
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#3
12-09-2013, 08:18 AM
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Also check for vacuum leaks, with the motor at idle cup your hands over the front of the carb and see if the motors idle speed picks up.
Check the PCV valve and make sure the ball rattles around. If you have a points type distributor check the wire that runs from the points out of the body to the coil. When age and dry rot breaks down the insulation on this wire it shorts out the spark when the advance weights pull the plate around and the problem can be only intermitant! This one can drive you nuts for a long long time if you do not confirm that its not a issue! More than likly its what Paul posted with todays gas going south and hanging up the Carbs power piston(s).
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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#4
12-11-2013, 03:05 PM
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Well, it's a Holley--and I did check the for vacuum leaks, but I didn't even have to have the car running-that large rubber hose coming from the intake that goes into the carb was ripped and loose--Duh-thanks Steve for the idea- the car is back to smooth operation.Thanks everyone for your ideas--
Josh |
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#5
12-11-2013, 05:06 PM
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Quote:
Any pics?
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Greg Reid Palmetto, Georgia |
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#6
12-12-2013, 07:46 AM
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If the car has power breaks, check that 3/8" ID hose also as most all the original hoses on any car dry rot at the same rate and you really need that hose when driving to be good!
__________________
Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
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