Running rich!....Bogs down at WOT!
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Running rich!....Bogs down at WOT!
Here's the facts:
* New GM Performance crate engine....350/300 hp
* Relatively new Holley 670 Street Avenger: (1) Float position correct (2) Fuel/Air mixture adusted to highest vacuum (3) Power valve OK (4) Accerlator pump adjusted to specs.
* Brand new Holley 135gph mechanical fuel pump (9 psi on the gauge)
* New plugs...after running 20-30 miles... Black with soot (indicates running rich...but no black smoke coming out of exhaust)
* Timing: initial 9*(800rpm) 2500rpm=36*
* Bogs down at WOT from a stand still and idicates running rich
WHAT IS GOING ON!!!???????
My mechanic is going to reduce the jet sizes in the carb...will that work? He, at first, installed larger jets...situation got worse...so logic tells us to go smaller...is that correct? How about the fuel pump...to large? HELP!!!!
* New GM Performance crate engine....350/300 hp
* Relatively new Holley 670 Street Avenger: (1) Float position correct (2) Fuel/Air mixture adusted to highest vacuum (3) Power valve OK (4) Accerlator pump adjusted to specs.
* Brand new Holley 135gph mechanical fuel pump (9 psi on the gauge)
* New plugs...after running 20-30 miles... Black with soot (indicates running rich...but no black smoke coming out of exhaust)
* Timing: initial 9*(800rpm) 2500rpm=36*
* Bogs down at WOT from a stand still and idicates running rich
WHAT IS GOING ON!!!???????
My mechanic is going to reduce the jet sizes in the carb...will that work? He, at first, installed larger jets...situation got worse...so logic tells us to go smaller...is that correct? How about the fuel pump...to large? HELP!!!!
Melting Slicks
Joined: Mar 2005
Posts: 2,838
Likes: 10
From: Austin TX
I'd go back to the stock "Avenger" jets (why the switch?). I'd also reduce the reg to 5-6 psi,..9 is too much and could be overpowering the needle and seat.
Do that and see how she runs.
If she still bogs at WOT I'd try different VS springs (stiffer).
Good luck!
Do that and see how she runs.
If she still bogs at WOT I'd try different VS springs (stiffer).
Good luck!
Melting Slicks
Joined: Dec 2006
Posts: 2,669
Likes: 3
From: Kingston Ontario
Check out " Jetting the transfer ports" by, NorvalWilhelm. Just posted yesterday in C3 tech/perf.
He says testing with an LM-1 shows that we are all running to rich. Good thread by a knowledgeable member.
He says testing with an LM-1 shows that we are all running to rich. Good thread by a knowledgeable member.
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
Do ya'll think the fuel pump is too much? (9 psi) I read the Holley Tech Support online and it stated that a Street Avenger 670 should have between 5-7psi and anything over 8 psi needs a regulator.... Thoughts, comments, opinions??
Safety Car
Joined: Oct 2000
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From: Southern Indiana
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Verdad Gallardo
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
I've never seen a Street Avenger that ran rich - they all run very lean out of the box, causing a very "flat" top-end. Every SA carb I've worked on needed about 3 jet sizes richer on the primaries, and significant enrichment on the secondary side to run right. Are you really sure you're actually seeing a rich condition...?
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
I've never seen a Street Avenger that ran rich - they all run very lean out of the box, causing a very "flat" top-end. Every SA carb I've worked on needed about 3 jet sizes richer on the primaries, and significant enrichment on the secondary side to run right. Are you really sure you're actually seeing a rich condition...?
I honest believe the fuel pump is WAY to big (pushing 9 lbs of fuel) I talked to a "gearhead" friend of mine who races Mustangs (sorry) and his 600hp, single Holley 750 runs at 7 lbs (always has and always will). He was STUNNED that I had so much pressure (with no regulator) going to the carb. He believes enough gas was pushing past the float's needle/seat that it was running rich enough to bog down and run crappy! So on Monday, I will go to the GM dealer and have them switch the monster 135gph Holley mechnical fuel pump with the smaller Holley 85gph fuel pump.
Race Director
Joined: Nov 2002
Posts: 12,142
Likes: 54
From: Taylor Michigan
I agree! Whenever I put in new plugs and run it about 30 miles, I pull the plugs and they are black with soot.... I don't see any black smoke coming from the tail pipes.
I honest believe the fuel pump is WAY to big (pushing 9 lbs of fuel) I talked to a "gearhead" friend of mine who races Mustangs (sorry) and his 600hp, single Holley 750 runs at 7 lbs (always has and always will). He was STUNNED that I had so much pressure (with no regulator) going to the carb. He believes enough gas was pushing past the float's needle/seat that it was running rich enough to bog down and run crappy! So on Monday, I will go to the GM dealer and have them switch the monster 135gph Holley mechnical fuel pump with the smaller Holley 85gph fuel pump.
I honest believe the fuel pump is WAY to big (pushing 9 lbs of fuel) I talked to a "gearhead" friend of mine who races Mustangs (sorry) and his 600hp, single Holley 750 runs at 7 lbs (always has and always will). He was STUNNED that I had so much pressure (with no regulator) going to the carb. He believes enough gas was pushing past the float's needle/seat that it was running rich enough to bog down and run crappy! So on Monday, I will go to the GM dealer and have them switch the monster 135gph Holley mechnical fuel pump with the smaller Holley 85gph fuel pump.
Drifting
Joined: Sep 2004
Posts: 1,959
Likes: 1
From: North Bend Ohio
I agree! Whenever I put in new plugs and run it about 30 miles, I pull the plugs and they are black with soot.... I don't see any black smoke coming from the tail pipes.
I honest believe the fuel pump is WAY to big (pushing 9 lbs of fuel) I talked to a "gearhead" friend of mine who races Mustangs (sorry) and his 600hp, single Holley 750 runs at 7 lbs (always has and always will). He was STUNNED that I had so much pressure (with no regulator) going to the carb. He believes enough gas was pushing past the float's needle/seat that it was running rich enough to bog down and run crappy! So on Monday, I will go to the GM dealer and have them switch the monster 135gph Holley mechnical fuel pump with the smaller Holley 85gph fuel pump.
I honest believe the fuel pump is WAY to big (pushing 9 lbs of fuel) I talked to a "gearhead" friend of mine who races Mustangs (sorry) and his 600hp, single Holley 750 runs at 7 lbs (always has and always will). He was STUNNED that I had so much pressure (with no regulator) going to the carb. He believes enough gas was pushing past the float's needle/seat that it was running rich enough to bog down and run crappy! So on Monday, I will go to the GM dealer and have them switch the monster 135gph Holley mechnical fuel pump with the smaller Holley 85gph fuel pump.
Why don't you just go th NAPA and get a reman Delco fuel pump for your car? The pressure will probably be real close to 5 to 6 PSI with this crappy old nothing fuel pump that has absolutely no BLING factor at all.
Why did you put this pump on your car in the first place? Do you even know how much horse power 135 GPH represents? What made you think your car needed this much fuel?
Oh well.
BigBlockk
Later.....
Thread Starter
Melting Slicks
Joined: Jan 2003
Posts: 2,713
Likes: 31
From: Shreveport LA
LA Events Coordinator
My wife keeps asking me that very same question...."Why did you (fill in the blank), when it calls for (fill in the blank)" You think I would have learned my leason from past experiences!!! I thought it would have been a better pump.....
I thought it would have been a better pump.....
Last edited by vetteguy75; Aug 25, 2007 at 08:02 PM.
Pro
Joined: Dec 2002
Posts: 560
Likes: 1
From: Mooresville NC
All the 135 GPH fuel pumps that I thought about buying required a regulator. So if you don't have one installed and you want to keep the 135 GPH fuelie, install a regulator. On Holley's, and I've played with a few since i was 18, if there is a speck of rust in the inlet needle it flooded the carb. I really good guess would be that the fuel pump pressure is over powering the inlet needle pressure.
Good Luck.
Good Luck.
