Strats off OK, but then goes rich after 20 seconds or so...
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Senior Member
Joined: Aug 1999
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From: This spot right here --->*
Car: 2002 SOM z28
Engine: LS1
Transmission: T-56
Strats off OK, but then goes rich after 20 seconds or so...
I don't think it is my A/F gauge or O2 sensor because it will do this regardless of if the engine is sitting for 1 day or 10 minutes. My thoughts are fuel pressure related (Carter mech pump 6-7psi).
It starts off in the normal range, then starts to richen up as it idles or I drive. If I cruise, then hit the gas a little, the gauge goes off the scale. I almost would expect it to do just the opposite (rich to leaner over time) as the choke opens... Is this a sign of a bad needle/seat?
My float level is good, maybe even a tad low. I lowered it down to #68 jets, but no effect to the rich idle/cruise. It idles great about 1000 rpms and drives rather well as is, but I think it could be better.
It is a Holley 750vac with electronic choke which does work and the whole carb is only about 5 months old.
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1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
It starts off in the normal range, then starts to richen up as it idles or I drive. If I cruise, then hit the gas a little, the gauge goes off the scale. I almost would expect it to do just the opposite (rich to leaner over time) as the choke opens... Is this a sign of a bad needle/seat?
My float level is good, maybe even a tad low. I lowered it down to #68 jets, but no effect to the rich idle/cruise. It idles great about 1000 rpms and drives rather well as is, but I think it could be better.
It is a Holley 750vac with electronic choke which does work and the whole carb is only about 5 months old.
------------------
1984 z28 w/ a 357 cu in. monster engine which is looking like the posterchild for Edelbrock with the exception of the Holley 750vac... all the suspension stuff... 9-bolt posi disk is in...
-=ICON Motorsports=-
Supreme Member
Joined: Sep 1999
Posts: 7,072
Likes: 13
From: Philly, PA
It gets richer becuase the fuel starts to vaporize better in the intake as more and more heat builds in the engine. It may briefly go rich if the choke doesn't pull off quite fast enough. Don't stress over O2 readings under any conditions other than a fully warmed up engine. There's no way you'll get it dead-on under all circumstances without closed loop control.
Supreme Member
Joined: Jul 1999
Posts: 2,010
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From: Homestead, Fla
o2 gauges don't even read untill they're warm anyway..mine has a built in timer from when it starts getting a signal to when it acutally displays.
besides..not counting a choke carbs get richer as hey get warmer...thats what a choke is for. to artificially richen the mixture while it's cold.
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"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports
besides..not counting a choke carbs get richer as hey get warmer...thats what a choke is for. to artificially richen the mixture while it's cold.
------------------
"American made baby. 100% American iron. The muscle among the masses. My hero. Yep, you can take your ergonomically designed, space age, computer controlled, 4 door, cup holding map lighted split double wishbone split fold down retractable cargo covered moon roof piece of transportation and keep it. For I have felt the thunder. And I know the difference!"
JSP Motorsports
ICON Motorsports
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