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7/7/10 7:04am - Original Message: 'flat spot'
manchestershark Lifetime Member
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Equinunk, PA - USA

Vette(s):
1972 conv, 4-speed, 350, 200hp, numbers match, rally wheels, war bonnett yellow w/white top. good condition, nice driver.

Joined: 10/31/2007
Posts: 1901
 Go easy on me now!  I have a old, rebuilt recently Rochester Carb. It seems to perform great after It comes off the initial opening of primaries. At idol, starting out in first gear, or after a slow down in any gear. The beginning of the throttle opening has a slight flat spot or hesitation. Am I to lean on air screws or is there a internal problem with carb? After it begins to accelerate, 12-1500 RPM it runs GREAT. Secondaries SLAM in and is seemless in performance. Do I live with it or try to remedy the flaw?  THANKS for the input.  CARLISLE is comming so I need to make a decision so I can look for something else if need be, new or used.  I am aware of the qualities of EDELBROCK, but would like to stay with OEM for gas economy and the originality.  Mark
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7/7/10 8:21am - Reply: 'flat spot'
BillinNashville
Former Member
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Vette(s):
1974 coupe. 350 CID with Turbo 400 trans. Decal says 8.5:1 compression. Needs paint and AC replaced but don't plan on full restoration. Car runs strong. No big problems so far. 67,000 miles on Odometer, probably rolled over

Joined: 7/3/2010
Posts: 65
It's been a long time since I worked on an old Carb but I do recall back in the day this was sometimes  caused by the accelerator pump. There was a little leather type cup it there and if it failed you'd get a flat spot on initial acceleration. That pump gives a little squirt of gas at intitial acceleration. If it doesn't you gat a lag, or flat spot. I don't know how to describe it but it will be on top of the carb probably on the bowl section. It's possible the bowl isn't filling all the way due to a stuck float.
This all from memory. Like I said it's been a long time.
But before I'd do anything drastic I'd check the Idle adjustment. Idle adjustment might also cause it and so can a faulty advance mechanism
BillinNashville2010-07-07 06:42:54

____________________________________
It has been over a year since I started. I had to quit the project so the car just sat in the garage. I was able to get started again in May 2012. As of July 27 2012 I have done the fiberglass repairs and applied Slick Sand High Build Primer.




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7/8/10 11:14am - Reply: 'flat spot'
VetteSpecialties
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Mounds View, MN - USA

Vette(s):
70 LT1 coupe, 69 350 HP coupe, 69 390HP 427 coupe, 71 LS5 convert, 85 coupe, 93 coupe

Joined: 5/24/2007
Posts: 1031
I agree.  I would also suspect the accelerator pump linkage.  Sometimes there are two holes to choose from, and there are adjustments on the rod.

Larry


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Corvette Specialties is your best source for Corvette parts, accessories and gifts. www.CorvetteSpecialties.com

   





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