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#1 |
Registered User
Join Date: Feb 2008
Location: Langley B.C.
Posts: 38
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Carb Problems Help!!
I seem to be having a similar problem when tuning carbs regardless of the carb type Holley, Rochester, or Carter. On hard acceleration it seems to stumble/hesitate or bog, I keep thinking this is caused by to much fuel but i'm not sure anymore. Could it be that it isn't getting enough fuel, or is it something completely different that i'm overlooking. Help would be great thanks.
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#2 |
Son of a gun
Join Date: Jan 2007
Location: Hot Springs, Arkansas
Posts: 1,636
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Re: Carb Problems Help!!
Yes it very well could be fuel...but if it did the same with all three carbs, I would start looking at timing first. What motor are we talking about here? I guess a small block, so try setting your dwell at 30, and your timing at 8 deg BTDC. That should wake it up pretty good. You can play with both to get in a "sweet spot".
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Bill BEATERS ARE NEATER Last edited by Bus Ted Knuckle; 04-01-2008 at 05:17 PM. |
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#3 |
Registered User
Join Date: Nov 2003
Location: Alexandria, VA
Posts: 1,534
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Re: Carb Problems Help!!
Sounds like you're not getting enough fuel on acceleration. Have you checked the accelerator pump in the carb in question for a worn/torn diaphragm or pump linkage out of adjustment/alignment. If you've had this same problem with multiple carbs on the same motor then you more than likely have a ignition timing issue as stated above.
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'72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction. ![]() ![]() ![]() |
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#4 |
Active Member
![]() Join Date: Jul 2007
Location: Centrally located between Houston, Austin and Waco. BCS area.
Posts: 7,947
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Re: Carb Problems Help!!
Lots of things can cause stumbling or bogging from fuel starvation, ignition components and/or vacuum leaks.
Need a little more info like, does it do it when cold or hot? And if you gradually depress the pedal, does it hesitate, miss or backfiire? Also, don't overlook vacuum advance leaking. |
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#5 |
Registered User
Join Date: Feb 2008
Location: Langley B.C.
Posts: 38
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Re: Carb Problems Help!!
I'm working with a Chev 350 in particular, but this has happened in many cases with other 350 engines. I have looked for vacuum leaks but none, I'm running it at 8 degrees BTDC, 38 degrees total. I've checked for fouled plugs, bad plug wires seems to be no ignition problems. It won't hesitate or stumble when I gradually step into the throttle only on hard acceleration for passing gear or just when I want it to haul ass off the line. As for hot or cold this has happened when the engine is hot or at operating tempature.
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#6 | |
Senior Member
![]() Join Date: Jul 2006
Location: Leander, Texas
Posts: 850
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Re: Carb Problems Help!!
Quote:
I had the EXACT same issue with my motor and after trying 4 different carbs I finally figured out that a vacuum secondary wouldn't work with my particular setup(heads). A double pumper fixed the stumble. It would literally fall on it's face under hard excelleration but it was fine if you slowly go into it. |
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#7 | |
Do the Dew!
Join Date: May 2005
Location: Vernal, Utah
Posts: 191
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Re: Carb Problems Help!!
Quote:
I do believe that this COULD be looked into further, if someone has the time. I think that I saw this in an Edelbrock manual, but I am not sure. Last edited by mtndewmaniac66; 04-02-2008 at 02:41 AM. |
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#8 |
Do the Dew!
Join Date: May 2005
Location: Vernal, Utah
Posts: 191
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Re: Carb Problems Help!!
With having the same problem with multiple carbs, I will say that it is not in the carburetors, unless you are one who is that unlucky.
I could surmise that your problem lies within the fuel delivery system. Fuel pump could be at fault, not enough pressure or fuel flow. Fuel filter could be partially plugged, or even the fuel filter inlet/outlet size, or fuel line size may be restricting fuel flow. Also something as simple as having several bends in a fuel line will restrict fuel flow. Another problem to look into is the fuel line between the tank and the fuel pump. It could be collapsing from a restriction in the line, or could be sucking in air from a connection. Another thing to look at is: timing, camshaft condition. This alone can cause stumbling. perform a timing check, look at the tining marks and see if advance is working properly, like stated above. (We need more info) Good luck! |
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#9 |
Gettin By on Gettin By
Join Date: Jan 2008
Location: Cedar Creek, Tx
Posts: 1,033
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Re: Carb Problems Help!!
I agree. Probably a stoped up fuel fliter or something with fuel delivery. I actually had an old locking plastic gas cap in my tank causing the same kind of issue. Guess the PO lost the key and just hacked the cap apart, with most if not all of it falling into the tank.
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