partial throttle bogging....help.(Ganey)
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Drifting
Joined: Mar 2001
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partial throttle bogging....help.(Ganey)
I was tuning my Holley today and playing with the timing just to see what more I can squeeze out of it. When I advanced the timing and richened the mixture a 1/4 turn. It was idling at 750 and I barely pulled the gas back and brought it up to 1500rpm and it was chuggin and running real rough. BUT, if I yanked the throttle it screamed to 5,600 like thothing. What should I do??
Drifting
Joined: Jan 2002
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From: Schaumburg IL
Re: partial throttle bogging....help.(Ganey) (Aaron-74)
I would make sure the basics of the carb are ok.
- Throttle return spring still on
- Linkage not binding holding secondaries open
- Vacuum secondary rod on the diaphram not bound up
So you have a base to work from ...
- Return idle mix back to normal.
- Set your timing to stock or whatever you ran.
The only way it can scream to 5600 from 750 is if the throttle blades primary and or secondary have opened up. Even if the PV ruptured the blades still have to open to get air into the engine.
- Throttle return spring still on
- Linkage not binding holding secondaries open
- Vacuum secondary rod on the diaphram not bound up
So you have a base to work from ...
- Return idle mix back to normal.
- Set your timing to stock or whatever you ran.
The only way it can scream to 5600 from 750 is if the throttle blades primary and or secondary have opened up. Even if the PV ruptured the blades still have to open to get air into the engine.
Thread Starter
Drifting
Joined: Mar 2001
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Re: partial throttle bogging....help.(Ganey) (bigvette1)
Throttle springs are a tight as can be. Sencondarys don't really open too much. It's all BRANDNEW. It's hard getting my kinda timing light on there with the headers. But, the vac. advance canister is pointed at the #5 cylinder. I don't know what timing a ran before because the cam was installed too far retarded..
Team Owner
Joined: Jul 2001
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From: Houston TX
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Re: partial throttle bogging....help.(Ganey) (Aaron-74)
I can't get a timing light on it. It's the kind of light that's got the springs that goes inbetween the plug and wire and has the clip to the light on that. And I can't use that because of my header. It kinda gets in the way.
I moved the dist back to where it was before I started. Put the idle/air screws all the way in and backed them both out 2 1/4 turn. It still does that. Could it be the float of the bowls?..the plugs or what..I am out of ideas.
I moved the dist back to where it was before I started. Put the idle/air screws all the way in and backed them both out 2 1/4 turn. It still does that. Could it be the float of the bowls?..the plugs or what..I am out of ideas.
Drifting
Joined: Jun 2000
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Re: partial throttle bogging....help.(Ganey) (Aaron-74)
Aaron,
First disconnect the vacuum advance line and plug the port (so you don't have a vac leak). Then check your timing at idle, whatever idle speed you picked. On the Corvette I think I am running about 12 degrees, Sub is about 10, crap I don't remember for sure. It's alot more than factory, I know that. Now, rev the engine and see when your mechanical kicks in and where it is all in. Should be all in pretty low, like less than 3K RPMs. Check the tech section already mentioned, Lars has some pretty specific guidelines. Don't know what else could be causing your problem, although it's kinda hard to diagnose accurately until you can drive it. But it shouldn't bog off idle in the driveway like that. I'd guess timing before I messed with the carb too much. Easier to mess with timing than mess up carb...
If you want, email me your current timing settings and post them here. We'll figure something out. Also, start out a little conservative (maybe factory settings) then start tuning from there if necessary.
Jeff
P.S. I will do whatever it takes to kick your butt when you get that thing on the road...it's going to be a beast!!
First disconnect the vacuum advance line and plug the port (so you don't have a vac leak). Then check your timing at idle, whatever idle speed you picked. On the Corvette I think I am running about 12 degrees, Sub is about 10, crap I don't remember for sure. It's alot more than factory, I know that. Now, rev the engine and see when your mechanical kicks in and where it is all in. Should be all in pretty low, like less than 3K RPMs. Check the tech section already mentioned, Lars has some pretty specific guidelines. Don't know what else could be causing your problem, although it's kinda hard to diagnose accurately until you can drive it. But it shouldn't bog off idle in the driveway like that. I'd guess timing before I messed with the carb too much. Easier to mess with timing than mess up carb...
If you want, email me your current timing settings and post them here. We'll figure something out. Also, start out a little conservative (maybe factory settings) then start tuning from there if necessary.
Jeff
P.S. I will do whatever it takes to kick your butt when you get that thing on the road...it's going to be a beast!!
Thread Starter
Drifting
Joined: Mar 2001
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Re: partial throttle bogging....help.(Ganey) (no_radio)
Well, Tomorrow I'm borrowing a better light that will work on my car from my g/f's dad (she's going to help me too) and I'll go to about 12-14 advance at idle. Then mess with the carb...
PS...I've got a 383 crank sitting on my floor behind me right now, Jeff. It's going to take more than heads to beat me :reddevil
Dont be mad that my V6 Silverado is louder than your 350HP Vette :lol:
[Modified by Aaron-74, 10:58 PM 6/2/2002]
PS...I've got a 383 crank sitting on my floor behind me right now, Jeff. It's going to take more than heads to beat me :reddevil
Dont be mad that my V6 Silverado is louder than your 350HP Vette :lol:
[Modified by Aaron-74, 10:58 PM 6/2/2002]
