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| Joined: | 09-17-2007 |
| Location: | San Francisco, California USA |
| Posts: | 221 |
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My background is:
73 Healey
2.0 Liter high compression with 104 Cams
Weber 45's
Delta headers and full 2.5" exhaust front to rear, flowmaster 44
Always wanted to run a wideband, after a complete top end rebuild and cam degree'd in just right the engine is running great and starts with minimal drama.
My current carb setup is:
Emulsion Tube F4
Main Jet 150
Air Corrector 170
Idle Jet 55 F9
Choke 38
Auxiliary Venturi 4.5
Pump Jet 55
Pump Exhaust 40
Stroke Pump Actuator Rod 14mm
Float Level 8.5-15mm
Never really dealt with a raw wideband reading in terms of a gauge. I used a speedhut unit with a Bosch LSU 4.9, it installed very easy and it's a pleasure to work with the gauge (very low profile). The readings are definitely not what I expected. This is an analog gauge made to look like an old Smiths gauge, and the needle bounces around quite a bit. I know this is now normal, as the gauge has a slight lag with carbs (only about a second) and it's never going to read a straight ratio. Digital gauges mask this phenomenon by updating the numbers which doesn't come off as such a big fluctuation, but the analog gauge really gives you an idea of how volatile the situation always is with internal combustion. You learn to read the flotation and kind of visually average it out to get the best idea of where it is.
Some of the readings I am getting currently:
Idle = 13-14 to 1 ratio
WOT= 8-11 to 1 ratio
Cruising at 3500-4000rpm = 12 to 1 ratio
Decel (closed throttle) = 15-16 to 1 ratio
The idle mixture screw has a DRAMATIC effect on idle mixture is all I can say. Sometimes a 1/4 of a turn yields 1-2 points +/- in ratio. I can easily get anything I like.
I have been snooping around the internet to see what people expect to see at WOT and closed throttle. Some say closed throttle should approach 20 to 1, which would mean a max lean condition (most fuel injection computers just shut the system down during closed throttle). Love to hear opinions on this. I am getting popping in the exhaust under hard decel and closed throttle, which seems like it is running too rich.
Haven't been able to do some freeway runs yet, just got some of the last exhaust welding done. Will fill in more information as it comes in, I have a feeling I will be finally re-jetting with something other than a hope and a prayer.
One thing I can also say is- what amazing people we had in the past tuning these things WITHOUT wideband. Every little turn of a screw makes a difference, and with wideband you can immediately see the results. How did anyone ever tune anything without this! Zen masters or something.