Running rich...
Running rich... Im starting to tune my LS1 carb set up and I ordered a Pro Systems carb, gave them all of my specs but man she runs rich. Its doesnt foul plugs but you can smell the fuel from the exhaust. I am running a MAP sensor on my vic jr. The motor is a stock bottom end, milled 243's (11.1 comp), stock valves, 760-780 Pro systems carb, I dropped the front jets down 2 sizes but still running rich. I am running a 160 T-stat, and the car doesnt get above 180deg running. Maybe I should run stock T-stat to get a complete burn in the combustion chamber?
Thanks
Thanks
does it burn your eyes at an idle? The primary jets wont affect anything but your part throttle cruise. With big cams you will almost always smell a rich exhaust, its just a product of valve overlap. If that's the case, try leaning out the mixture screws a little, you may not be able to lean it out and still have the motor start/idle happy.
Last edited by Horsepwraddict; Oct 1, 2014 at 04:43 AM.
does it burn your eyes at an idle? The primary jets wont affect anything but your part throttle cruise. With big cams you will almost always smell a rich exhaust, its just a product of valve overlap. If that's the case, try leaning out the mixture screws a little, you may not be able to lean it out and still have the motor start/idle happy.
What is a wideband? I do have a vacuum gauge. I was also thinking, maybe its blow bye? I only run one PCV in the intake and its baffled. Maybe I should run another in the valve cover?
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h8tulooze, I am willing to bet that your idle screws were already 1.5-2.0 out when the carburetor came from Pro-Systems. What you are talking about is a pretty common complaint. What most guys find that actually works is closer to 3/4 of a turn out on all 4 idle screws.
I would start at 1.5 out and turn them in each 1/4 of a turn equally until the car starts to get fussy. As you turn the screws in, you may need to screw in the throttle screw to raise the idle some.
Turning them in will lean the idle out. Turning them out will richen the idle. Try to run it as lean as you can where it will still idle and drive nicely. So turn them in as far as you can and still get good behavior. make sure they are all equal.
I would start at 1.5 out and turn them in each 1/4 of a turn equally until the car starts to get fussy. As you turn the screws in, you may need to screw in the throttle screw to raise the idle some.
Turning them in will lean the idle out. Turning them out will richen the idle. Try to run it as lean as you can where it will still idle and drive nicely. So turn them in as far as you can and still get good behavior. make sure they are all equal.
h8tulooze, I am willing to bet that your idle screws were already 1.5-2.0 out when the carburetor came from Pro-Systems. What you are talking about is a pretty common complaint. What most guys find that actually works is closer to 3/4 of a turn out on all 4 idle screws.
I would start at 1.5 out and turn them in each 1/4 of a turn equally until the car starts to get fussy. As you turn the screws in, you may need to screw in the throttle screw to raise the idle some.
Turning them in will lean the idle out. Turning them out will richen the idle. Try to run it as lean as you can where it will still idle and drive nicely. So turn them in as far as you can and still get good behavior. make sure they are all equal.
I would start at 1.5 out and turn them in each 1/4 of a turn equally until the car starts to get fussy. As you turn the screws in, you may need to screw in the throttle screw to raise the idle some.
Turning them in will lean the idle out. Turning them out will richen the idle. Try to run it as lean as you can where it will still idle and drive nicely. So turn them in as far as you can and still get good behavior. make sure they are all equal.
Speed,
I did what you said and I cant really tell a difference. My idle went up a little and I had to adjust the idle screw to bring it back down a little. I also checked my plugs but them seem fine.
Just out of curiosity, what are your cam specs? My car does this same thing. Some cams have enough overlap, etc that they are just stinky at an idle. I've played with idle screws, drilled the idle air bleeds, and it's a little better, but still stinky. Eric L
wideband or vacuum gauge IMO. i run mine around 13.3 AFR at idle just because it makes cold starts much better. you're making a guess at best by just turning screws and sniffing your tail pipe. probably wouldnt hurt to bump the idle timing some too.
Idle timing is 22 deg. Not sure what wideband or vacuum gauge you are referring to.
A wideband is a great tuning tool because it will tell you if you are rich or lean and how much at any given point. Whether it is idle, WOT or transitions, it can quickly tell you where you are at.
What it can't do is tell you what is ideal. A lot of guys fall into the trap of saying my WOT A/F has to be this number or the idle A/F ratio has to be this number. Cars never seem to listen to reason. They want what they want.
But, if you are having drivability issues and you are not sure if you are rich or lean, it is great for that. Also, if you have black plugs or white plugs and you are not sure when it is too rich or too lean, the wideband will tell you. I find them incredibly handy when fine tuning your transitional fuel mixtures.
A wideband is great for helping you find the best powervalve and make adjustments to you to your idle air bleeds and idle fuel restrictor circuits if you really like to fine tune.
While alot of guys like to set their idle and mixture screws by a vacuum gauge, I find it pretty useless for these applications. Some people also use it to choose their powervalve. I think that is pretty ineffective as well.
What it can't do is tell you what is ideal. A lot of guys fall into the trap of saying my WOT A/F has to be this number or the idle A/F ratio has to be this number. Cars never seem to listen to reason. They want what they want.
But, if you are having drivability issues and you are not sure if you are rich or lean, it is great for that. Also, if you have black plugs or white plugs and you are not sure when it is too rich or too lean, the wideband will tell you. I find them incredibly handy when fine tuning your transitional fuel mixtures.
A wideband is great for helping you find the best powervalve and make adjustments to you to your idle air bleeds and idle fuel restrictor circuits if you really like to fine tune.
While alot of guys like to set their idle and mixture screws by a vacuum gauge, I find it pretty useless for these applications. Some people also use it to choose their powervalve. I think that is pretty ineffective as well.
