6.0 carb problems
On The Tree
Joined: Mar 2010
Posts: 196
Likes: 1
From: London,Ontario,Canada
carefull playing with air bleeds Before you do any tuning you must make sure the fuel pressure is no more than 7lbs and the float level is correct.The engine needs to be at operating temp. If your carb has four corner idle circuit you need to start with all four idle screws about 3/4 turn out from bottom. On your car you should be able to adjust the idle with both the front/rear idle speed screws. They need to be adjusted the same amount. Like a few others have stated you need at least 14-16* timing at idle. With the big cam your vacuum at idle will be pretty low and open plenum intake makes it worse.
The idle air bleeds help above 1300 rpm and up until you get on the main circuit which can be anywhere from 1900 to 2200 rpm on the primaries. The idle screws are for idle.
After this if the car still loads up you need to get into the idle restrictore inside on the meetering blocks.
With-out an O2 for tuning you are guessing and wasting your time.
ALSO you can not trust the smell of the car. The new fuels have crazy additives and are very missleading. You can not tune by tail pipe color or even plug reading as unleaded fuels are just nasty. Example is look at your daily driver that's fuel injected, check out that shiney black tailpipe. Looks rich.
Long winded. I hope this helps and not confuse you.
Had a car on the dyno to-day and the guy thought he had it tuned right because it idled like a pro stock. Sounded mean. But my god was like 11.2 A/F at idle. Car was drowning in fuel. Cleaned it up to 14.5 at idle and WOW , crisp response, then fixed the high idle with air-bleeds.
Takes a while to get to the end but it's just around the corner. Not how much you spend, But how you spend it.
Dyno crazed for 25 years and still learning.
Aleck
The idle air bleeds help above 1300 rpm and up until you get on the main circuit which can be anywhere from 1900 to 2200 rpm on the primaries. The idle screws are for idle.
After this if the car still loads up you need to get into the idle restrictore inside on the meetering blocks.
With-out an O2 for tuning you are guessing and wasting your time.
ALSO you can not trust the smell of the car. The new fuels have crazy additives and are very missleading. You can not tune by tail pipe color or even plug reading as unleaded fuels are just nasty. Example is look at your daily driver that's fuel injected, check out that shiney black tailpipe. Looks rich.
Long winded. I hope this helps and not confuse you.
Had a car on the dyno to-day and the guy thought he had it tuned right because it idled like a pro stock. Sounded mean. But my god was like 11.2 A/F at idle. Car was drowning in fuel. Cleaned it up to 14.5 at idle and WOW , crisp response, then fixed the high idle with air-bleeds.
Takes a while to get to the end but it's just around the corner. Not how much you spend, But how you spend it.
Dyno crazed for 25 years and still learning.
Aleck
Thanks guys, I am going to play with the timing and idle screws. Im going to check to make sure I got the fuel pressure right. Last time I checked it was around 6.5. Ive played with the float levels too so I think I got them right. Once I get the money Im going to try to find a good shop that has a wideband.
OP, apologies for the hijack!
Aleck,
I wish mine would idle with 14.5 AFR! I have a Holley HP750 with a Proform annular booster body (no choke). I have to have mine set around 12.8 AFR at idle or it stalls when dropped in gear (3600 stall 9" PI Vig) or even if the wheel is turned (power steering). My idle screws are out about 5/8 turn (all four) and I'm running 45° total at idle speed (20° chipped and 25° MAP). Also fouling plugs, any ideas?
...Had a car on the dyno to-day and the guy thought he had it tuned right because it idled like a pro stock. Sounded mean. But my god was like 11.2 A/F at idle. Car was drowning in fuel. Cleaned it up to 14.5 at idle and WOW , crisp response, then fixed the high idle with air-bleeds.
Takes a while to get to the end but it's just around the corner. Not how much you spend, But how you spend it.
Dyno crazed for 25 years and still learning.
Aleck
Takes a while to get to the end but it's just around the corner. Not how much you spend, But how you spend it.
Dyno crazed for 25 years and still learning.
Aleck
I wish mine would idle with 14.5 AFR! I have a Holley HP750 with a Proform annular booster body (no choke). I have to have mine set around 12.8 AFR at idle or it stalls when dropped in gear (3600 stall 9" PI Vig) or even if the wheel is turned (power steering). My idle screws are out about 5/8 turn (all four) and I'm running 45° total at idle speed (20° chipped and 25° MAP). Also fouling plugs, any ideas?
OP, apologies for the hijack!
Aleck,
I wish mine would idle with 14.5 AFR! I have a Holley HP750 with a Proform annular booster body (no choke). I have to have mine set around 12.8 AFR at idle or it stalls when dropped in gear (3600 stall 9" PI Vig) or even if the wheel is turned (power steering). My idle screws are out about 5/8 turn (all four) and I'm running 45° total at idle speed (20° chipped and 25° MAP). Also fouling plugs, any ideas?
Aleck,
I wish mine would idle with 14.5 AFR! I have a Holley HP750 with a Proform annular booster body (no choke). I have to have mine set around 12.8 AFR at idle or it stalls when dropped in gear (3600 stall 9" PI Vig) or even if the wheel is turned (power steering). My idle screws are out about 5/8 turn (all four) and I'm running 45° total at idle speed (20° chipped and 25° MAP). Also fouling plugs, any ideas?
you must be running a fairly aggressive cam, that has very little manifold vacuumat idle???
whats happening is: as soon as you put it in gear, you are loosing manifold vacuum,and then you also loose a bunch of timing - since you are adding so much by the map sensor- so the motorslows down and stalls. my .02
Its all making sense now. So if I use the map sensor set my timing at 10 or 12 degrees of timing? About what do I set my rpm timing and idle timing at? Also I got a laptop with windows vista will I beable to use it or do I need to find a older laptop? I ordered a cable adapter for my laptop. Oh yea can I run a vacuum line from my carb to my map sensor?
TECH Regular
Joined: Oct 2006
Posts: 417
Likes: 1
set your vac advance at about 10 degrees at max vac and then less as the vac drops so that at WOT you have no vac advance, just run off the map. make sure you use the right vac port on your carb, some are fixed vac which may not work, you want the port that shows true vac at idle (cant remember what they call them).
your laptop might not work with msd software if its very new, unless they changed the software, i use a very old laptop with serial port for comms.
ignition needs to be on to talk to the msd box, egine doesnt have to be running if you dont want you can still adjust the map.
your laptop might not work with msd software if its very new, unless they changed the software, i use a very old laptop with serial port for comms.
ignition needs to be on to talk to the msd box, egine doesnt have to be running if you dont want you can still adjust the map.
Ok I got to messing with the msd program and tried to transfer it to the controller and some reason it wont let me. Is it because my of my laptop. Its about 2 years old and it has window vista. I bought a cable that connects to a usb port.
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You may need to download the new version of the software from the MSD site...it's compatible with Vista or 98/XP. Also make sure you're using the right port on the port menu(in the MSD program).
gotta thanks, now I got to play with it some more and learn the sweet spots. Seems to run alot better by what little bit I did earlier. Took car down the road for the first time and it pulled real hard. Hope to make a few passes next week. Gotta go over everything and change the oil.
0 out the map graph and work only on your timing curve. If your running a high stall or steep gears you won't be needing vacuum advance. Most 4 corners need around 3/4 of turn out on all four corner. start there and find your way around. If that doesn't produce what you need turn the back ones all they way in then turn the front ones out 1 1/2 turn out each side.
Without knowing your compression and total set-up. 30-32 degrees total with the zeroed out map graph. When you get to the track tune by your MPH. Make a pass or 2 at 30 degree's, then make 2 passes at 32 degree's if MPH goes up continue to 34. When the MPH falls off you've gone to far go back to your best setting.
