6.0 carb problems
05-16-2010, 10:03 PM
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6.0 carb problems Hi Im trying to figure out my carb on my mustang. By all means I know nothing about a carb. This is my first build and my first carb vehicle. I order a carb from pro systems built to my specs. My problem is with the cold starts. Its wanting to foul the plugs but after I clean it out for a min it runs and starts back up fine. Its a LQ4 with a 244/250 .612/.620 with a 113lsa with a set of patriot 317 heads milled compression around 10:1. I have the msd 6010 with the curve 6 chip. My fuel system is areomotive A1000 pump with the fuel pressure set around 7. I thinking its in the carb but dont know how to fix it.
05-17-2010, 09:24 AM
#6
If I remember correctly the pro systems carbs don't have chokes. You should expect a little trouble gettting it running with no choke. Generally that means blipping the throttle and keeping the RPMs up until it warms up a tad.
Are you running a MAP sensor with the MSD box? Doing so made my car easier to start. 10° or 12° of vacuum advance should help.
Fouling plugs when cold sounds like your idle screws need to be turned down a bit. An overly rich idle will work like a choke, but you don't want to run that way. I assume the pro systems guy walked you through all of that?
Last having grown up with carb'd vehicles I can tell you every one has it's own way it likes to be started. you can't just turn the key like on a FI motor. Generally two full pumps to the floor, then hold the throttle half way down before cranking helps it kick over in the morning. Don't pump it too many times or the accel pump will flood the engine. Once it fires you may need some quick stabs at the throttle when it starts to stumble so the accel pump can take the place of your missing choke.
Are you running a MAP sensor with the MSD box? Doing so made my car easier to start. 10° or 12° of vacuum advance should help.
Fouling plugs when cold sounds like your idle screws need to be turned down a bit. An overly rich idle will work like a choke, but you don't want to run that way. I assume the pro systems guy walked you through all of that?
Last having grown up with carb'd vehicles I can tell you every one has it's own way it likes to be started. you can't just turn the key like on a FI motor. Generally two full pumps to the floor, then hold the throttle half way down before cranking helps it kick over in the morning. Don't pump it too many times or the accel pump will flood the engine. Once it fires you may need some quick stabs at the throttle when it starts to stumble so the accel pump can take the place of your missing choke.
05-17-2010, 10:10 AM
#7
If I remember correctly the pro systems carbs don't have chokes. You should expect a little trouble gettting it running with no choke. Generally that means blipping the throttle and keeping the RPMs up until it warms up a tad.
Are you running a MAP sensor with the MSD box? Doing so made my car easier to start. 10° or 12° of vacuum advance should help.
Fouling plugs when cold sounds like your idle screws need to be turned down a bit. An overly rich idle will work like a choke, but you don't want to run that way. I assume the pro systems guy walked you through all of that?
Last having grown up with carb'd vehicles I can tell you every one has it's own way it likes to be started. you can't just turn the key like on a FI motor. Generally two full pumps to the floor, then hold the throttle half way down before cranking helps it kick over in the morning. Don't pump it too many times or the accel pump will flood the engine. Once it fires you may need some quick stabs at the throttle when it starts to stumble so the accel pump can take the place of your missing choke.
Are you running a MAP sensor with the MSD box? Doing so made my car easier to start. 10° or 12° of vacuum advance should help.
Fouling plugs when cold sounds like your idle screws need to be turned down a bit. An overly rich idle will work like a choke, but you don't want to run that way. I assume the pro systems guy walked you through all of that?
Last having grown up with carb'd vehicles I can tell you every one has it's own way it likes to be started. you can't just turn the key like on a FI motor. Generally two full pumps to the floor, then hold the throttle half way down before cranking helps it kick over in the morning. Don't pump it too many times or the accel pump will flood the engine. Once it fires you may need some quick stabs at the throttle when it starts to stumble so the accel pump can take the place of your missing choke.
agree with this, my demon 750 doesnt have a choke and 2 pumps of accelerator will get it fired then hold the throttle part open for 1-2mins until the car is warming, then it will idle ok.
ignition timing is msd6010 with 18deg cranking, with 23deg of timing once fired, then +10 deg via vacuum advance at idle, so a minimum of 33deg while idling which really cleaned up the exhaust emissions and made it much happier idling.
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05-17-2010, 11:11 AM
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agree with this, my demon 750 doesnt have a choke and 2 pumps of accelerator will get it fired then hold the throttle part open for 1-2mins until the car is warming, then it will idle ok.
ignition timing is msd6010 with 18deg cranking, with 23deg of timing once fired, then +10 deg via vacuum advance at idle, so a minimum of 33deg while idling which really cleaned up the exhaust emissions and made it much happier idling.
ignition timing is msd6010 with 18deg cranking, with 23deg of timing once fired, then +10 deg via vacuum advance at idle, so a minimum of 33deg while idling which really cleaned up the exhaust emissions and made it much happier idling.
05-17-2010, 05:31 PM
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Ok I will play with my msd as soon as I can find a adapter for my laptop. How do I run a map sensor? My intake dont have a place for it. Also which way do I need to go with the air screws to lean it out? The plugs look bad when I pull them and some are gas soaked. Patrick at pro systems is very helpful but I just dont understand somethings hes telling me. Oh yea it dont have a choke.
05-17-2010, 05:37 PM
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Oh yea when starting it, I can pump it just once and it will fire off. Thats what I was doing holding the accelator for about a min and it would start idling fine but now its back to fouling the plugs. Missing badly at start up. I will try the program for the msd but oh boy thats gonna be fun. Never done anything like that. Thanks guys
05-17-2010, 06:46 PM
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Just came back from dynoing my 6.0 with a msd 6012 and a Prosystems carb today. You may have to go with bigger idle air bleeds on top of the carb to lean up your idle. They are the 2 outside little jet looking things on top of your carb next to the front middle squirter. Check his tech sheet that he sent you with the carb and it will tell you which number air bleeds you should go with to lean it out.
05-17-2010, 06:56 PM
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Just came back from dynoing my 6.0 with a msd 6012 and a Prosystems carb today. You may have to go with bigger idle air bleeds on top of the carb to lean up your idle. They are the 2 outside little jet looking things on top of your carb next to the front middle squirter. Check his tech sheet that he sent you with the carb and it will tell you which number air bleeds you should go with to lean it out.
05-17-2010, 07:13 PM
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You have to have really small drill bits to do the job and a good drill press to center everything. It might be easier to just order a couple of diffrent air bleeds from summit racing. Check Patrick's recommendation on the build sheet and see what is the highest air bleed you can go to. I'm thinking that you can jump to a 79 or 80. But check your sheet.The bigger the air bleed the more air you can let in at idle to lean it out.
05-17-2010, 08:20 PM
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You have to have really small drill bits to do the job and a good drill press to center everything. It might be easier to just order a couple of diffrent air bleeds from summit racing. Check Patrick's recommendation on the build sheet and see what is the highest air bleed you can go to. I'm thinking that you can jump to a 79 or 80. But check your sheet.The bigger the air bleed the more air you can let in at idle to lean it out.
05-18-2010, 11:20 AM
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i'd send the carb back and tell them to make it right if not call chuck nyutten and have him build you a carb .i've had 2 from him and both were spot on .. no changes needed
05-18-2010, 02:52 PM
#16
I wouldn't go messing with air bleeds until you set the idle adjustment screws.
Air bleeds adjust the timing of the circuit, i.e. when the carb switches from the idle to the main circuit. But the idle screws set the mixture right at idle.
If you can't get a wideband O2 sensor on the exhaust, then adjust the screws to get the maximum manifold vacuum. Turn all 4 screws to the same number of turns out. Make sure your engine is fully warmed up first.
By the way, best way I have found to drill blanks is by chucking the blank in a cordless drill and holding the drill bit with a pin vice. You can get sets of numbered drill bits and a hand held pin vice on ebay for like 10 bucks. Hobby stores that sell things like model airplane also sell bits.
http://www.amazon.com/MINI-DRILL-IND...4212199&sr=8-8
Air bleeds adjust the timing of the circuit, i.e. when the carb switches from the idle to the main circuit. But the idle screws set the mixture right at idle.
If you can't get a wideband O2 sensor on the exhaust, then adjust the screws to get the maximum manifold vacuum. Turn all 4 screws to the same number of turns out. Make sure your engine is fully warmed up first.
By the way, best way I have found to drill blanks is by chucking the blank in a cordless drill and holding the drill bit with a pin vice. You can get sets of numbered drill bits and a hand held pin vice on ebay for like 10 bucks. Hobby stores that sell things like model airplane also sell bits.
http://www.amazon.com/MINI-DRILL-IND...4212199&sr=8-8
05-18-2010, 09:48 PM
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thanks, Im gonna try the idle screws first. Ive played with it several different ways but really dont understand prosystems directions on the idle screws. Im gonna try to get a wide band soon. Its about to break me tho, going to have to regroup. Thanks again
I wouldn't go messing with air bleeds until you set the idle adjustment screws.
Air bleeds adjust the timing of the circuit, i.e. when the carb switches from the idle to the main circuit. But the idle screws set the mixture right at idle.
If you can't get a wideband O2 sensor on the exhaust, then adjust the screws to get the maximum manifold vacuum. Turn all 4 screws to the same number of turns out. Make sure your engine is fully warmed up first.
By the way, best way I have found to drill blanks is by chucking the blank in a cordless drill and holding the drill bit with a pin vice. You can get sets of numbered drill bits and a hand held pin vice on ebay for like 10 bucks. Hobby stores that sell things like model airplane also sell bits.
http://www.amazon.com/MINI-DRILL-IND...4212199&sr=8-8
Air bleeds adjust the timing of the circuit, i.e. when the carb switches from the idle to the main circuit. But the idle screws set the mixture right at idle.
If you can't get a wideband O2 sensor on the exhaust, then adjust the screws to get the maximum manifold vacuum. Turn all 4 screws to the same number of turns out. Make sure your engine is fully warmed up first.
By the way, best way I have found to drill blanks is by chucking the blank in a cordless drill and holding the drill bit with a pin vice. You can get sets of numbered drill bits and a hand held pin vice on ebay for like 10 bucks. Hobby stores that sell things like model airplane also sell bits.
http://www.amazon.com/MINI-DRILL-IND...4212199&sr=8-8
05-18-2010, 10:19 PM
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You want to start by turning the front air bleeds in all the way. Then back it out between 1.5 to 2 full turns tops. If you do this and still doesn't help you with your problem then it's time for air bleeds.
05-19-2010, 09:23 AM
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Yea Ive done the air screws several different ways and dont think its helping at all. I cant even stand behind the car when its idling, its so rich it just burns my eyes. I am going to try bigger air bleeders.