I have dual weber 44 idf's on my 2258. I was having a problem with one of my cylinders and found that the main circuit had some sort of black booger plugging most of the main circuit of cyl 2 and a small on in cyl 3. I completely cleaned everything and reassembled. The car is driving way better. I set the floats at 11.5 without the gasket.
Now I am having the other problem- my car is always too rich. At idle my a/f ratio is 13:1 which is ok for me. If I try to lean it out any more then I get popping on decel at low rpm's. On the main circuit, I am using 125 mains, f11 et, 210 ac and I am consistently around 10.2:1.
I can but smaller mains but it seems like I shouldn't need that small of mains.
My setup-
idles-50
mains-125
et-f11
ac- 210
vents- 34
Any ideas of how to lean the main circuit?
Will the car pop when it is to rich or to lean cause my car pops too and I thoyght it was to rich.
smaller vents, try 32mm.
increase the velocity of the air charge.
rich
pulls like a demon @3k+ yes?
Good call John. Must have read that wrong after a 12 hr day. That's actually a strange scenario with the main jets the OP has. Idle around 13 A/F ratio isn't horrible, but with a 125 main and an F11 ET, that would, in practice seem actually a little small. I run 135s on a 1.8 with an F11 ET. Any smaller on the mains would be on paper, too small, as would an A/C jet of anything larger than the 210 he has now. But in theory it would lean it out some.
What are the float levels like? Have you set them since the carbs have been on the car? How about fuel pressure?
Which cam are your running and how are your heads setup?
When an engine always runs rich I question exhaust efficiency and engine combination.
good insight jake. thanks!
I decreased the size of my vents to 32 and the car seemed to respond we however my A/f ratios are still off. The other things that I noticed is that with larger vents, if I leaned out the carbs too much- I would get a pop on decel. Now it seems to pop earlier than it did with larger vents. I do not think this is a exhaust leak cause it does go away if I richen the condition slightly. I have also checked with a fog machine and didn't see a leak.
Also- some things that I forgot to mention is that I have 1 5/8 inch headers with a triad exhaust. The car is mainly used for spirited street driving. It seems like most of my driving is done older 3500rpm. I have a very wide variety of jets, vents, et. however the smallest mains that I have is 125 however I have ordered a bunch more so I will have smaller options soon.
Looking at houses again next week. Last day at current job Oct 15 unless OH board of medicine holds slows the license down due to bureaucracy issues I hate dealing with bureaucracy.
All the places I look at have big man cave garages
By decreasing the vent size you just lowered the RPM at which you came on the main jets and enriched the mixture throughout the jet range. You also decreased your top end potential. I would have expected it to exacerbate your current problem. What was your AFR reading with the 32's?
The only reason I'd decrease the vent size would be to cure a lean transition issue or enhance low RPM drivability.
On a side note, my handy dandy chart says the 36 vent is right for you with a 6K redline. They should also lean out your mixture.
Initial jetting is always a SWAG and each engine is unique. My gut would say 140-150 mains but I would also never think you'd be at 10-1 with 125's and 34 vents.
I've had 2 sets of Weber 44's with 36 vents on 2 different engines (both 1914 cc's). Main jetting ranged from 135 to 165. 135's with 220 AC jets for the daily driver (Kombi Bus) and 165's with 190 AC jets on my 8,000 RPM drag bug.
I initially had lean transition problems with both of them. Almost lost an eyebrow from a lean pop on the bug. I stepped up to the 55 idle jet and F7 ET and never looked back. Love that ET.
In another thread Racer Chris mentioned increasing the AC jet size to bring the main jet in sooner which would help with lean transition. I've never tried it, it messes with my understanding of the AC jet somewhat but in theory might work. (Purely speculation here since trying to wrap my head around it) A larger AC jet (less restricted) should make it easier for a lower vacuum signal to pull air through the jet stack resulting in flow through the mains sooner.
My understanding was that the AC size didn't come into play until that size started to restrict airflow (higher RPM with more air volume travelling through AC jet). Small sizes restricted sooner, enrichening mixture and larger sizes restricted later giving you a leaner mixture.
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