Carbs going rich
Posted: Sat Jun 03, 2017 6:06 am
Engine specs
2332, 10:1 CR, 86C, 48IDFs with 40vents, CNC Wedge ports and big beef manifolds.
Over the years I have been slowly improving on my jetting and have now settled with a combo which works best.
Needless to say, this combo can still have some improvements.
Which is where I need help.
Around 3000rpm to 4000rpm the engine runs pretty rich, hitting 9.5:1 AFR at times. This sometimes causes misfires.
Then from 4000 to 5000 it sits steady at 12.5:1
Then from 5000 to 6000 it slowly leans out steadily to 14:1
I have tried heaps of jet combos and have kept a basic log of what each setting has given me, but now I need help from basic Weber tuning to something a bit more advanced... That or I need to bite the bullet and go for fuel injection.
Jetting is currently 57idles, F11 emulsions, 155 mains and 160 airs.
Going smaller on the mains helps the mid range richness but everywhere else it goes too lean.
I cant get smaller air jets to richen up the top end.
I have tried F11, F2 and F50 emulsions which is all the emulsions that I have. Buying emulsion tubes gets very costly very quickly.
O yes, this is a street car so mid range rpm is important.
I have read that F2 emulsions are supposed to lean out the mid range more than the F11. But this isnt what I am seeing. The F2 makes the mid range even richer. Above 4000 they behave nicely, but I struggle to get the engine above 4000. And once again, leaning out the main jet means I cant get rich enough at the top end. Even using 145 mains, I still get 9:1 AFR at around 4000.
With the F2s I just cant get close enough to warrant spending more time on them. The F11s are better.
The F50s are just plain crap in my car - I cant get close with them. F50/165 main/200 air I go as lean as 17:1 around 5500rpm, with 4000rpm at 9:1. Swapping to F50/165/160 helps the top end, but I still lean out around 14:1.
FWIW, I hit 131kW on the wheels today at a Subaru dyno day. So the car is making power.
I am now considering advancing the timing over the rich areas but I dont like creeping up on the timing - call me chicken???
Any advice or suggestions would be greatly appreciated
2332, 10:1 CR, 86C, 48IDFs with 40vents, CNC Wedge ports and big beef manifolds.
Over the years I have been slowly improving on my jetting and have now settled with a combo which works best.
Needless to say, this combo can still have some improvements.
Which is where I need help.
Around 3000rpm to 4000rpm the engine runs pretty rich, hitting 9.5:1 AFR at times. This sometimes causes misfires.
Then from 4000 to 5000 it sits steady at 12.5:1
Then from 5000 to 6000 it slowly leans out steadily to 14:1
I have tried heaps of jet combos and have kept a basic log of what each setting has given me, but now I need help from basic Weber tuning to something a bit more advanced... That or I need to bite the bullet and go for fuel injection.
Jetting is currently 57idles, F11 emulsions, 155 mains and 160 airs.
Going smaller on the mains helps the mid range richness but everywhere else it goes too lean.
I cant get smaller air jets to richen up the top end.
I have tried F11, F2 and F50 emulsions which is all the emulsions that I have. Buying emulsion tubes gets very costly very quickly.
O yes, this is a street car so mid range rpm is important.
I have read that F2 emulsions are supposed to lean out the mid range more than the F11. But this isnt what I am seeing. The F2 makes the mid range even richer. Above 4000 they behave nicely, but I struggle to get the engine above 4000. And once again, leaning out the main jet means I cant get rich enough at the top end. Even using 145 mains, I still get 9:1 AFR at around 4000.
With the F2s I just cant get close enough to warrant spending more time on them. The F11s are better.
The F50s are just plain crap in my car - I cant get close with them. F50/165 main/200 air I go as lean as 17:1 around 5500rpm, with 4000rpm at 9:1. Swapping to F50/165/160 helps the top end, but I still lean out around 14:1.
FWIW, I hit 131kW on the wheels today at a Subaru dyno day. So the car is making power.
I am now considering advancing the timing over the rich areas but I dont like creeping up on the timing - call me chicken???
Any advice or suggestions would be greatly appreciated