Wideband Results

[Zed999]

[[email protected]]

what is

idle timing hose on
idle timing hose off
3500 RPM timing hose on
3500 RPM timing hose off?

Also, have you indexed the jets, instead of trusting they are as marked? Very frustrating to go down on a jet and have it run richer.
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[Zed999]

[[email protected]]

the engine will run cooler as you move away from 14.7:1, EITHER WAY.

Your timing is good, so move on. Aim for 13:1 on the mains.

For progression, target

16:1 if you want to maximize MPG
13:1 if you do not care about MPG.
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[Zed999]

[tattooed_pariah]

Ok, re-read my weber tech manual pages again, FINALLY understood it.. if i do something and someone explains it, i catch on fast, but i'm a downright terrible book reader..

Larger main jet + smaller AC should richen everything.. i'm running 55 idles, and tried changing ACs to 170 (only thing i have below 200). No change. AFR still says lean at idle and air when moving. Upped mains from 115 to 130, then to 140. No change on the gauge.

I'm beginning to wonder if my o2 sensor is reading properly.. it's a brand new plx dm6 system.
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'72 Volksrod "Effigy"

"Never worry about stepping on people's toes. People who get their toes stepped on are either sitting down, or standing still on the job."
-Admiral Arleigh Burke, USN(ret.)

[clonebug]

A PLX is pretty fool proof.

What happens when you turn the key on but don't start the engine???

It should default to 14.6 on the DM6 for about 10 to 15 seconds until the self check gets done then it will count up until it goes full LEAN....
Once you start it after that it should read the AFR.
You do not want to let the sensor heat run much before starting the engine due to condensation being able to ruin the sensor.

Let the sensor warm up as the engine is running so you don't shock the sensor.
Make sure you have the sensor mounted in a 10:00 or 2:00 o-clock position to keep it as far away from moisture as possible.
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[tattooed_pariah]

[sled]

Im sorry if this an obvious answer but, did you calibrate the sensor in free-air correctly?
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drive your split.

[tattooed_pariah]

[sled]

[303epps]

This isn't a question about my wideband results but I hope to get some advice on a starting point to jet my weber IDF's.

What I have is a 79 and 82 series weber, not matched but left and right, the ones with the 5 progression ports. I'm hoping to install them onto a 2017 being finished up for break in. The 2017 has a web 163, Tim's Stage 1 heads, 1.25 rockers on the intakes - 1.1 on the exhaust and an AA 1-1/2" exhaust.

The webers will have 32 mm ventures and 3.5 aux ventures and 1-5/8" velocity stacks. The emulsion tubes are F67.

what's a good starting point for the jetting on this combination?

Thanks,
Eric

[clonebug]

[Zed999]

Heavy poptop late bay camper.
Type-4
71x 104, 2413cc
Original 2L cam. (Solid refaced followers/european carb cam)
Under 8:1 CR with high deck.
Compression test 165-167psi on all 4.
Bosch SVDA from a 2L, pertronix and "flame thrower" coil. Set at 7.5 idle which gets approx 31-32 total mechanical advance.
Stock original heat exchangers, stock Ernst exhaust.
DRLA40'S
32 vents
.2 emulsions
48 idles
180 airs
145 mains

Stacks out, pumps backed off
Down progressively from 58 to 48 idles.
48s read 14.5 to 17.
The engine is happier than ever, not spluttering and runs higher cht than before which in this case I think is good, it's nowhere near hot, just hotter, it feels better.
So I'll order some 45 idles which I believe are the smallest available. I was hoping at some point to find a jet small enough to make it pop and stumble so I could go back up a size and know for sure I was as lean as possible. Maybe the 45s will do that.

Meanwhile, like a naughty schoolboy, I tried 140 mains but it pinks WOT.
Back to 145s, WOT from1500 to 4500rpm it gets progressively richer from around 14.5 to 10.8. Could this be evened out with different airs?
The tall airs I have are marked 180. A 2mm drill shank checked with a micrometer is much too big to fit through then so if they are drilled it's not by much. I think they're most likely as marked.

[[email protected]]

you have too much ignition timing. Try 28 total. Your distributor is giving too much advance, ideally you'd bend the advance stops in to limit the advance more.

Remember per this thread, you may be too rich but have too much timing. Back out the timing and you can lean the main circuit a little more, and it will likely run better.
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It's just advice, do whatever you want with it!

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[Zed999]

Thanks John, I'll try that. If it's good I'll look into bending the stops. It will tick over with a lot less advance but I guess it won't pull away well?

[[email protected]]

normal good timing is around 8-10 BTDC at idle, 28-30 BTDC full advance (no vacuum).
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It's just advice, do whatever you want with it!

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[Zed999]

Timing set to 28 max. Ticks over around 4 or 5 but happily ticks over.

WOT AFR is a little less spread over the revs. It now starts off around 14 at 2000rpm but still gets to 10.8 by 3500-4000 rpm.

At constant speeds
40mph = 14.0 afr
45mph = 14.5 afr
50mph = 15 afr
55-60mph = 13.1afr yee ha but weird
70mph = back leaner at 14 afr

I do have a lean hole between idles and mains but it's at loads where my idles on their own would have been long over. When I had bigger idles, any constant speed between 40 and 70mph produced 13.5afr.

I like my lean idles in terms of saving fuel but right now I feel I've temporarily ruined the driving experience. It's slower accelerating from any speed/revs and makes more noise doing it. I think my mains always came in late and now I've reduced the idles it's very noticeable. WOT it seems like the mains are only fully working at high revs (3500-4,000) where they are too rich. Constant speed or reasonable acceleration and they're too lean apart from at ,constant 55-60mph for some reason. CHT's are fine, 250-350f max.

I'm resisting the temptation to bung the big idles back in and set the timing back to 30-31 but I seem to be gradually making it drive worse so far!

Bigger airs? With dells I can't completely remove the tall airs as they hold the stack in. If I could I'd try that.

[[email protected]]

what throttle position?
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It's just advice, do whatever you want with it!

Please do NOT send me Private Messages through the Samba PM System (I will not see them). Send me an e-mail to john at aircooled dot net

"Like" our Facebook page at
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[Zed999]