Zenith TIN Emulsion Tube Testing

[VFR750]

The other learning is the zeniths really like small air correction jets. Stock was 185. After messing with 175 and 165s for years, I really stared at the data in the summer of 2017.

Smaller was needed.

I went to 155s, liked them.

With the new cam, even smaller was needed. I went even further: 145. And I really like them. But again, no hard data. Too hot!!

[Blue Ghia]

All of the graphs of the mixture vs rpm show a initial lean, then quite rich shifting to lean again. All of the emulsion tubes seem to be variations of the same pattern. Did you find any way to hold the entire mixture curve between 12 and 13, or reduce the rich zone at 3000 rpm?

[VFR750]

Good observation. And yes I figured it out

Basically I had to decrease the air correction jets down to 145. This allows me to use leaner main jets. Many say go bigger correction jets. but by going smaller I tipped the lean part to be richer, and then I could lean the whole range.

I think that is what I really learned was the data did point out the subtle impact of the emulsion tubes.

And changing from a SC cam to a DC40-102 cam dramatically improved the way the carburetors work. The carbs really want overlap and an open exhaust.

Interestingly I put a muffler on the car last week that hurt the midrange by dropping afr down into the 9s! It hurt 3000, but really took off at 4000. It’s coming off.

[VFR750]

Two things have really hurt data collection, mostly the Bosch 4.2 O2 sensors are not lasting more than a couple of months. That and my hero 5 GoPro is a poor replacement for my workout hero (1)

[Hi_Fi_Guy]

Just wanted to say I appreciate this thread.