After reading posts by ZL1Power, I also bought a Innovate Motorsports digital exhaust analyzer. Seeing how the a/f changes up and down over the entire rpm range and different throttle settings I don't know how I ever got a carb setup correctly before. An amazing tool! I don't think I could set a carb again without one.

I was running at only 11:1 a/f from idle to about 2500rpm. 13.5:1 above that. This was using #65 jets in my 950HP Holley and having completely removed the idle air bleeds! Changing the high speed air bleeds from #32 to #35's brought the a/f to 14.5:1, but makes for very lean running above 2500rpm. I ran out of time to try more combinations. I expect that I will need to increase the jets by at least 4#'s and perhaps drop the air bleeds to #34's.

The unit is great in that you can see exactly what the a/f is doing in real time. It will also connect to the MSD tach output and record 43 minutes of data while driving to be played back on my laptop.

This hasn't been cheap, $450 for the analyzer with rpm converter, plus $175 for the Holley air bleed kit. But the results have been very gratifying giving the engine a much greater smoothness and response than ever before. I was making great power with the setup before. Full throttle dyno runs showed 13.6:1 a/f making 483rwhp; but, the part throttle operation was never what I thought it should be. I thought changing to the solid roller cam would make the difference. Quite honestly, it wasn't that much smoother than the factory L88 cam that made the 483rwhp and also got 15mpg on the highway using 6th gear. The vacuum was a bit higher, 12hg vs. 7.5hg, but the engine didn't feel any smoother. I now believe that I would have probably made huge improvements even with the factory L88 cam had I had this digital analyzer earlier. Well, no going back now!

When I think of all the guys thinking that single digit mileage is all you can expect with a Vette I believe I will actually get darn close to 20mpg on the highway once I'm done with an L88! The car is not used for mileage, but it is a good indication of the state of tune making the car much more crisp and responsive along with more power compared to an eye burning rich setup.

It's amazing how my clothes didn't smell of gas after my tweaking session today. My goal is to have the a/f around 15:1 for cruising and 13.5:1 for power. I know I can now get it just right!

Chuck



[Modified by Chuck Harmon, 12:37 AM 4/24/2004]

 

I have a wide band A/F meter that I bought about 10 years ago for around $2500.00. It has both a digital readout as well as an analog. At times I have been happy with this unit but mostly frustrated.

It has no data logging capability so you have to watch what is going on very closely. Also, with the 542 I had in my '67, it would stop reading at certain times - like idling, under certain cruise conditions, and when backing off the throttle when going down a hill. It works all the time in my Callaway with the small cam but with the cam I had in the 542 it was a different story. And now with the cam in the 632 I know I will be in for more of the same.

Chuck, does the Innovate unit have any quirks such as this? Does it ever stop giving a readout? Have you had any problems with it?

Steve

 

i'll chime in,
my $140 2 cyl setup is great at idle, but it does stop at cruise.
no data logging sucks, i would take notes at a red light.

 

Dataq makes an excellent datalogger for ~$25. Look up the 194RS starter kit here:
http://www.dataq.com/


I've been using one for more than 2 years with very good results, logging a WB O2 analog
voltage output along with an RPM signal from a DIY tach transducer:
http://www.corvetteforum.net/c4/doctorj/pix/dataqsc.jpg
http://www.corvetteforum.net/c4/doctorj/carwb.htm

 

I went ahead and bought the Innovate Motorsports unit today. It will be interesting to see how it works with my combination.

Steve