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Weber 38 Wb Readings - Lean On Anything Else Than Wot?


GreenSwede

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WOT at 13 sounds great to me. I've no idea what else you need to do to get midrange dialed in.  :D  Others who know the top part of a carb from the bottom (and are reading do know, though!

 

(I hope so! Will try smaller airs. I need a store with jets around the corner!!))

 

How's the motor feel now, compared to when you were 14.5+ at WOT?

 

Cheers,

 

It feels good! Easier to get the rear out if I want to.. ;)

 

I might be imagining, but I think one hears the difference. The leaner state more of a wailing sound, and now a more aggressive growl. Exaggerated of course, but a small change of tone.. :) With an AFR this is quite fun, just sorry I'll have to wait for jets a few days. This car is becoming more fun every day. Still, after owning it for 21 years.

Edited by GreenSwede

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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until about 5500 rpm then leans out.

Yup, smaller airs.  Probably quite a bit smaller, as they don't have as dramatic an effect as the mains do.

 

And yes, there's a 'bark' at about 13:1 that- your backside will agree- means more power.

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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  • 2 weeks later...

Installed smaller airs today, 175. WOT now just above thirteen up to about 4- 4500 rpm, then starts to lean out and at 6000 rpms it's about 14.5. Not as lean as before, but too lean. I guess I´ll try even smaller airs.

 

But first I've got to replace a rear wheel bearing, which has I HUGE play (I can make it say "clunk" with one hand). Huge enough that I won't even test drive to see AFR until it's done. A perfect WOT is no fun if my rear wheel passes me. I have now reasonable excuse for not noticing it before..

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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how do the plugs look ?

I have no idea=) Haven't checked, figured I'd get closer to what I want, then check.

 

For long periods of high rpm full throttle the 200 (2mm) needle and seat is too small.  We always use the 250 on our track cars.  We also use a fuel pressure of about 4 psi which is just a bit higher that internet wisdom suggests.

Jeff

 

Thanks, Jeff. But, these wasn't long periods, mostly accelerations from 2nd gear low rpm up to 6000 rpm on 4th. But. I'll keep that in mind while on the track.

 

Though, your cars had more aggressive cams, and more time to burn fuel?

 

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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  • 3 weeks later...

So, with a good, used rear stub and hub I'm at it again. 145 mains, and now 165 airs.


 


I don't get the exact same reading every pull, but to sum up and give an average:


 


Now, low RPM WOT is a bit richer - full throttle at about 2500-3000 rpm starts at 11.5 to 12ish and stops at 13 and remains there until 6500. 


 


So a bit rich on low RPM's - which is the main jet territory, right?


Should I go slightly smaller on mains?


 


I guess backing back to bigger (in between somewhere, like 170) airs would get me lean on high RPM's. And I don't want that. On 175 airs I ended up around at about 14.5 at 6000 rpm, so a decent guess would make 170’s do 13.7, which from what I’ve learned seems lean on WOT and high RPM’s.


 


Here's a 30 second example - one minute into the clip - for the most representative of WOT acceleration. The start is mostly a flickering needle..



Edited by GreenSwede

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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It feels good, I think. Dumb thing - it's been sitting for a while since the last test run, I installed the smaller airs after replacing hub and stub - so memory is vague. 

But, it might have had a bit more growl on low RPM WOT before, when closer to 13. Or that might just be cause I now know that I want 13..=) 

Maybe I'll try a smaller set of mains, just to see - but I guess both that and a bit larger airs would make me go lean at higher RPM's. 

 

Cause I shouldn't  put these singular pulls into the "longer periods" of full throttle Jeff mentioned and consider needle and seat, should I?

Edited by GreenSwede

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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I'd pop 140 mains in just to see what happens.  I know the airs shouldn't affect lower revs, but...

 

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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I gotta start this whole thing with my car. Just got it started today for the first time. 12.5 at idle, 13.1ish at light throttle then just a tiny but more and it'll cruise at 14.7. So lots of playing left to do... I need to put better gas in 'er too...

-Nathan
'76 2002 in Malaga (110k Original, 2nd Owner, sat for 20 years and now a toy)
'86 Chevy K20 (6.2 Turbo Diesel build) & '46 Chevy 2 Ton Dump Truck
'74 Suzuki TS185, '68 BSA A65 Lightning (garage find), '74 BMW R90S US Spec #2

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I'd pop 140 mains in just to see what happens.  I know the airs shouldn't affect lower revs, but...

 

t

 

Exactly what I'm going to do. (Since it seems to affect lower revs as well)

 

Will report back. And maybe I'll have another look at the idle..

Edited by GreenSwede

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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Another run with the same jets. I took a detour on my way from work. And filmed it, getting a better view of the tach. The glare in the afr mostly goes away after a short while. Figured I'do a run in the same spot after putting in the 140's. Again.

 

 

Ola Gustafson
Sweden
-------------------
1975 Taiga Euro 2002 3685483 - Weber 38/38 DGMS - Pertronix Ignitor - H&R Cup Kit - TEP headers and Simons 2" sport exhaust - 3.91 LSD.

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