Carb tweak
here is a question. if it cruises at 14.5 with the converter locked at 70mph, wouldnt changing the IFR lean out that higher rpm AFR too? or am i thinking about it wrong. what the OP and i are experiencing is 10.9 AFR at extremely light throttle (cruising around a neighborhood or slow traffic) then it leans up to the desired AFR at cruising speed.
So if you have too little or too much of the transfer slot showing at idle it won't transition well.
Second, I agree with you the air bleeds are suppose to flatten out the AFR as air flow increases. Some links say "delay", I'm not really sure which is correct. But I do know from basic physics that without an air bleed the AFR will get increasingly more rich as the air flow increases. So what I do with the transition and main circuits is set the AFR at the low end of the band with the jets/IFR, then adjust the air bleeds if it goes rich/lean at the top of the band for that circuit.
Again, Speedtigger says "it's not that simple", but I have had pretty good luck with this approach. I am often in 5th gear before 30 mph. I can cruise in 5th gear at 1000 RPM.
Two things. I had a similar problem that went a way once I adjusted the throttle screws to get 20 thou of the transfer slot showing. Adjusted both primary and secondary the same way. This put my idle with a stock LS2 cam at 1600 rpm. Only way I had to get it back down was to back off the timing at idle only.
So if you have too little or too much of the transfer slot showing at idle it won't transition well.
Second, I agree with you the air bleeds are suppose to flatten out the AFR as air flow increases. Some links say "delay", I'm not really sure which is correct. But I do know from basic physics that without an air bleed the AFR will get increasingly more rich as the air flow increases. So what I do with the transition and main circuits is set the AFR at the low end of the band with the jets/IFR, then adjust the air bleeds if it goes rich/lean at the top of the band for that circuit.
Again, Speedtigger says "it's not that simple", but I have had pretty good luck with this approach. I am often in 5th gear before 30 mph. I can cruise in 5th gear at 1000 RPM.
So if you have too little or too much of the transfer slot showing at idle it won't transition well.
Second, I agree with you the air bleeds are suppose to flatten out the AFR as air flow increases. Some links say "delay", I'm not really sure which is correct. But I do know from basic physics that without an air bleed the AFR will get increasingly more rich as the air flow increases. So what I do with the transition and main circuits is set the AFR at the low end of the band with the jets/IFR, then adjust the air bleeds if it goes rich/lean at the top of the band for that circuit.
Again, Speedtigger says "it's not that simple", but I have had pretty good luck with this approach. I am often in 5th gear before 30 mph. I can cruise in 5th gear at 1000 RPM.
Float levels
Transfer slot within range
Secondary linkage functioning properly and adjust correctly
Accelerator pumps adjusted properly
Proper jets and powervalve (factory calibrations)
I also agree that in general the IFR will affect the low RPM cruise A/F ratio more while the LSB will affect the higher RPM crusie A/F ratio more.
Ok guys need a little help. Mods in sig. I have a quick fuel slayer 750 vacumm secondary. 70 main jets, 82 secondary, 6.5 power valve. My afr at idle is around 14.1. Then while light accelerating from 1500-2500rpm it's rich at 10.9. Then when cruising around 2300 rpm I have it running 14.5 afr. When I kick it it goes a little lean at 15.0, need to play with the pump cam some and the secondary opening rate. WOT is around 12.9. I'm mainly wanting to fix the light acceleration rich problem any idears? Thanks
Have a look at my answer above. They are related like you suggest, but they are biased like Pops mentioned. So, you might think of them as a pair. A smaller IFR and LSB package could tend to lean out the bottom while still having a similar ratio to one another as opposed to a larger IFR and LSB package can maintain the same ratio to one another while being richer down low.
Took the truck out tonight and WOT was bouncing around 12.5 to 14.1. I realized too when i was cruising I was on my primary circuit. So I jetted up to 71 primary to help WOT. I tried to adjust the idle mixture screws some more and now have it idling around 14.4 and cruise is around 13.2. Still all the same 10.9 while accelerating. The truck runs like a bat out of hell but I know there has to be more power on the table. Definitely need to do more reading and trial and error, I'm not as swift as I thought I was
Messed around some tonight and put a wire in my IFRs to help out I can tell a difference. Dropped the main jet down to a 70 and found out the secondary was actually 72. I have it at around 14.5 idle and it likes to stay in the low 13s under light throttle and will sometimes dip to low 12s. Cruise is jam up running right around 15. Gonna try to work on it a little more later this week.
Ok if I'm driving and don't come to a complete stop but the engine is at idle rpms it has a slight stumble when I get back on the gas. Also at very light cruise it will sometimes go lean at 16 afr. Idle mixture screws don't seam to make much of a difference I'm thinking of trying a smaller diameter wire and then readjusting the mixture screws. Any thoughts?
Ok if I'm driving and don't come to a complete stop but the engine is at idle rpms it has a slight stumble when I get back on the gas. Also at very light cruise it will sometimes go lean at 16 afr. Idle mixture screws don't seam to make much of a difference I'm thinking of trying a smaller diameter wire and then readjusting the mixture screws. Any thoughts?
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo