89gmcs15

iTrader: (7)

my pro systems carb was sent out with quite large air bleeds (about .076) on the idle bleeds and tiny ones on the inside one (about .028)... it would only want to idle without dying to have the idle afr set to about 11.8:1-12:1... to have the screws set out about 1 5/16 turns that yielded a 13.5:1 afr at idle, but ya pull the truck into gear and the afr spikes out to 18+:1 and the engine wants to die. well i didnt like the stink and burning eyeballs at idle with it so rich so i decided to dig into this mess alittle.

so i was thinkin it needed to have bigger air bleeds in so i drilled the bleeds to .082 and it only made it worse. it would only want to idle if you had it set to 11.2:1 or richer. so i got confused and got creative.

i took the tiny air bleeds and put them in the primary and tuned it for that and kept the large bleeds in the secondarys and tuned it all for that. BINGO! i could run almost 13.2:1 and it wouldnt move or want to die really any when i pulled it into gear.

i drilled out some air bleeds with smaller holes (.065) and now it takes only 3/4 turns out to get to 13.2:1 but when ya pull the truck into gear and it doesnt drag the engine down or change the afr more than .1 or .2 but i cant lean it out any more without it going super lean then when i pull it into gear.

any ideas on why this is? should i go smaller yet to try and get the afr closer to 14:1 at idle and cruise or call 13.2:1 good? if i remember right im running 24* of timing at idle. im getting happier with the engine but man its taking time. like months of research and hours and hours of tuning, missed the whole racing season but theres always next year!

ZONES89RS

iTrader: (25)

If you have it that close call it good. If you do not mind messing with it more, go ahead. Things are not as they were with my TA either. When I come to a stop the engine wants to die. Never did that in the RS so now I have to get the wide band on to see what the fuss is about.

Pop N Wood

iTrader: (1)

Try opening up the idle feed restrictors a bit. That should give you a bit more gas in the transition circuits.

Also pull the carb off and measure how much of the transfer slot is showing. You should have around 20 thousands of an inch. Any less and it will cause AF issues right off idle.

89gmcs15

iTrader: (7)

Thanks for the help so far. Ive opened the restrictors from .035 to .037 and it seemed to help untill I tried to lean the idle out. Im back again to having 2 different sized air bleeds in the idle spots. Half of them are at .056 and half of them are .085. Im not sure if this is ok for the engine or not. Any help would be appreciated and sorry for any misspelled words, im on my phone typing this.....

Pop N Wood

iTrader: (1)

By two different sizes I assume you mean front to back (primary to secondary) and not side to side? no disrespect, just having a hard time following what you are saying.

I have the same size IFR and idle air bleeds in the primary and secondaries. That is a huge split you have now, I can't imagine that is right. Out of the box I think the carb had the bleeds within a couple of drill sizes of each other.

The secondary IFR and air bleeds really don't come into play until you just start to get into the secondaries. You should be able to set up your slow throttle transitions on the primary side then just set the secondary to match.

I have read of some guys who disconnect the secondary linkage when they are setting up the transition circuits.

One thing that helped me is keeping detailed notes so I could back out any changes that go too far.

89gmcs15

iTrader: (7)

I double checked yesterday and the smaller bleeds (IFR?) are infact .030 and I drilled the larger idle bleeds from .075 to .082 so im not sure why but it was a huge split between the 2.
It might be wrong and you can make fun of me for doing it but I do actually have one corner of the idle bleeds the same and the opposite corner the same, not the primaries the same and the secondaries the Sam. I was worried about it leaning the back cylinders out I guess.. Im going to unhook the secondaries today and try that. Its like I get it to run good and idle good then get after it and **** changes.... I wish I could just send the motor off to get tuned on a dyno ha but I know my luck and it would get back and run like *** still. Thanks again for the help and sorry again for spelling or changed words. Im on my phone again ha

Pop N Wood

iTrader: (1)

Man you gotta be careful. the air bleeds are on the top of the carb. The outer ones are for the idle/transition circuits. The inners are the high speed air bleeds for the main circuits.



The ones in the front of the carb are the primaries. The back are the secondaries.

Idle feed restrictors (IFR's) are in the metering block. They are like the main jets. I believe the pro systems carbs put them here. Yours might be press in. If they are then you will need to drill them out and put in a set screw that you drill to the right size.



To get your off idle AF right you need to be adjusting the outer air bleeds and IFR's only. the inner ones will affect the AFR at upper RPMs.

If you bought the carb from pro systems then perhaps you should call them and have them help you.

Speedtigger is a member here who just when through a year or so saga getting his pro system carb to work off idle right. You might look into what he did.