Zenith jets question

[silver356]

Due to the great threads here about rebuilding Zeniths, I took it upon myself to rebuild the carbs on my 1970t (believed to be a stock 2.2). Ive had it about two years, but it has mostly been sitting waiting for body and paint work. But now I'm getting it up and running, and the weak point seemed to be the Zeniths. They were popping and spiting under load, but would idle fine.
I did a pretty good rebuild, but left all of the jets set as I found them-

Idle 47.5
main 115
Pump jets 30

The enrichment circuit had already been removed. When I put them back on the motor, lots of spitting and popping, and I had to screw the idle adjustment screws out to 5-6 turns to get them to calm down. They would balance, but any load caused them to freak. A call to my helpful mechanic suggested that I needed to bump up the idle and main jets because they were running too lean. I stayed with the 30 pump jets, but ordered up some new jets, so now I'm running

Idle 50
main 120 ( I also bought 125's if I need them)

Its better, as now I'm at 3.5-4.5 turns out, and they are all balanced. While I was doing that, however, I realized that my air correction jets were 195. I have read as many threads as I could on Zeniths, and it struck me that that may be my problem. Too large an air correction jet could lead to my too lean settings, correct? Should I change them for something in the 170 range? If I do that, should I go back to smaller idle and main jets?

Any advice much appreciated!
David

[VFR750]

If you don't have a wideband air-fuel sensor and gage you'll have a much harder time tuning them up. The best you can do to richer them up.


120-130 mains with 170-180 air correction
50-52 idles
The 30 accel jets are probably too small. I've already drilled mine out to 42. I'm on a 3.0 and it seems to want even more.

But these are just suggestions based on my experience on my 3.0.
I'm at
162 mains
165 air correction
60 idle
125 idle air correction modified housing using performance oriented kit.
42 accel jets

[yelcab1]

Originally Posted by VFR750

If you don't have a wideband air-fuel sensor and gage you'll have a much harder time tuning them up. The best you can do to richer them up.


120-130 mains with 170-180 air correction
50-52 idles
The 30 accel jets are probably too small. I've already drilled mine out to 42. I'm on a 3.0 and it seems to want even more.

But these are just suggestions based on my experience on my 3.0.
I'm at
162 mains
165 air correction
60 idle
125 idle air correction modified housing using performance oriented kit.
42 accel jets

I have the same problem. Where do I buy these jets?

[VFR750]

eBay. Search under alfa1750. Many different parts for zeniths. Based in Italy.

Just ordered a set of emulsion tubes.

[ganun]

Originally Posted by VFR750

If you don't have a wideband air-fuel sensor and gage you'll have a much harder time tuning them up. The best you can do to richer them up.


120-130 mains with 170-180 air correction
50-52 idles
The 30 accel jets are probably too small. I've already drilled mine out to 42. I'm on a 3.0 and it seems to want even more.

I agree with VFR, 190 air is too much.... for comparison your engine has a displacement of 367cc/cyl. , close to what I have at 392cc/cyl. but Weber.
My main is 120, with 180 air correction
50 idle
35 accel pump.
I'd say go with 115 summer / 120 winter mains and 180 air, if it stumbles on accel then go to 35 accel jets.
Bigger air correction leans out the top end, bad on the track.

[70basket]

I let my Zenith's set for about 6 months. I thought I had flushed them out pretty good beforehand but when I went to install them I popped off an accelerator pump cover and it looked like it was half full of baby powder. Even after what I thought was a good cleaning I fought idle pop for a while I kept removing the idle jets and spraying carb cleaner it is now 95% improved. I am running a stock 2.2 with stock jets and the mixture screws open about 5+ turns.