Jetting advise based in AFR readings

[Luftgekült]

Hi,
I'd noticed a lack of power in my engine below 2500rpm. Thinking in rejeting, I installed a LC-1 wideband. As I suposed the engine is working very rich.
I went from 50's to a set of used 47's idles i had, but it made no change, I would even say that it is going richer.

Here are my engine specs,
1914cc - 40x35 valves - w120 cam - ac net SVDA - 8:1 comp

and carbs'
dual 40IDF - 120 mains - 50 idles - 200 airs - 28 venturis

my AFR readings are roughly
Idle --> 13,5
1000 - 2000 rpm --> 9,8 - 10,5
2500 rpm --> 12,5
3000 rpm --> 12
3500 rpm --> 12
4000 rpm --> 12,5
>4500 rpm --> 12,8 - 13

what jets should I try next??

thanks!!
_________________
'71 VW 1302 1300cc in progress....
'72 VW 1302S 2109cc
'84 Passat Variant GL 1.6TD

[Eaallred]

Are these reading ast WOT?

If so, I would start by changing the mains one size smaller. Airs look like they're coming in just fine.
_________________
Eric Allred

You have to remember something: Everybody pities the weak; Jealousy you have to earn.

[Luftgekült]

[grimace007]

just curious but your checking these under a load right?
_________________
Brian
68 sedan

Dallas Air Coolers

[Luftgekült]

[[email protected]]

next stop

47.5
115
180

John
Aircooled.Net Inc.
_________________
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[Luftgekült]

Thanks for the replies,
well, I made new tests.

Fuel pressure is 3 psi. Stock fuel pump with pressure regulator.
Floats set.
Tests made in 3rd gear, full throttle, steep slope.

I changed to:

115 mains
45 idles
185 airs

My AFR readings are a bit better.

Idle --> AFR 13,5 Screws 1,5 turs out
1000-1800 rpm --> 12
2000 rpm --> 10.5
2500 - 3000 rpm --> 13.5
3500 rpm --> 12.5
5000 rpm --> 15

It starts to lean from 3500 till the end, reaching +15:1 at 5000rpm. I have to try smaller airs but not sure of how many sizes do I have to down.

I have another issue with a rich condition at 2000rpm. Looks like a rich progression from idles to mains. I can't go leaner on idles because 45 is the smaller size, I believe.

It has F11 emulsion tubes. I have a set of F7s, would it make any difference?

My other questión is about accelator pump. If I stomp on the gas the engine reponds well (instant rich condition, AFR arround 11:1) but I does not respond well to slight changes (16 to 20 AFR) How can I fix that?
_________________
'71 VW 1302 1300cc in progress....
'72 VW 1302S 2109cc
'84 Passat Variant GL 1.6TD

[Luftgekült]

Please help

After I figure out the jetting I going to take the car to the dyno, then change to 44IDF and post the results.

One thing I forgot is that I am using an Empi GT exhaust which I believe is seriously reducing engine's performance. Waiting for a CSP supersport to arrive...
_________________
'71 VW 1302 1300cc in progress....
'72 VW 1302S 2109cc
'84 Passat Variant GL 1.6TD

[74driver]

Follow Johns advice from aircooled.n*t. He has probably forgotten more about vw jetting than you or I will ever learn.

[Bruce]

You should measure the diameter of your idle jets. There's no way a 45 should produce an A/F ratio of 10.5:1
_________________

[Scott Novak]

What are the float settings?

Is it just me or does anyone else think that the 28 mm venturis seem a little small for a 1912cc engine?

Scott Novak