I'm thinking of buying an A/F ratio monitor or something like that. Are there different kinds? What is a good kind to buy? I'm also wondering how you can look at the numbers and know what a good ratio is and what is too rich and too lean. Is there a chart or something?

I don't think my Q-jet's secondaries open without load, because the air valves don't, so would be revving and checking the ratio in park be an incorrect thing to do?

Also, as far as idle mixture goes, you just back out each screw and when it starts to sputter and want to die, you go back a half turn or so? Thanks.

Can't go wrong with this one.

http://www.innovatemotorsports.com

Taylor,
The Inovate one seems to work excellent. I have tested it a little against the $2000+ one on my dyno & so far the numbers are very comparable as far as I can tell.
I will have more info after I get the RPM inteface for the Inovate so I can compare them with more accuracy,
As it stands I don't really have a way to overlay the two accuratly.
But as I said it looks very close.
You cannot set the AFR (except at idle) unless the engine is under a load.
You want to check at full load, cruise load & idle.
Whacking the throttle in the driveway will do nothing except annoy the neighbors :D

The Inovate will record about 45 minutes of data that you can download to your computer as well as read in real time so you dont need to watch it all the time.
And the price is excellent.
Don't bother with the JC Whitney $29.95 single wire crap it will tell you next to nothing graemlins/sad.gif

Only $350 for a wide band a/f gauge? Thats awsome. I know what Im saving up for smile.gif

Isn't that only for cars with oxygen sensors? Or am I missing something? Where do you plug that into?

You get a bung to weld into the exhaust system, then add the O2 sensor. In temp applications you can mount it ion the tail pipe with a clamp.

Later
Steve

Originally posted by 71chevy0192:
Isn't that only for cars with oxygen sensors? Or am I missing something? Where do you plug that into? =
It comes with a Bosch wide band sensor & weld in bung & plug.

I cheaped out with this one from JCW

Air/Fuel gauge (http://www.jcwhitney.com/webapp/wcs/stores/servlet/ProductDisplay?productId=70&catalogId=10101&langId=-1&storeId=10101)

For my purposes it works fine. I bought a 3 wire universal Bosch O2 sensor, welded in a bung(non fouler adapter cut in half).

No numbers, just a bar graph. I've tuned my 454 to 20mpg and an 8.6 1/8th mile et with it.

I second the LM-1 sensor/meter. Best tool I've ever bought. I use it both on my truck and Camaro.

I personally wouldn't use a narrow band sensor even if it was free, IMO.

So how can you tell what good numbers are, or does it tell you what the 'optimal ratio' is?

Well, it's a darn good bet that best power is made from 12.5-13:1 A/F ratio, so it's easy to find that on the meter. On the track you can go up or down a jet if you want to see if it picks up any.

As far as cruise goes, go 14.5-15.0 for best economy, usually 14.7 being the best. For idle, I go for 14.7-15.0, which is actually hard to do. You'd be surprised how sensitive those idle mixture screws are (even on a 4-corner) are at that lean ratio. Just the slightest clockwise turn bumps it up to about 16.5:1. And if you're the type to install the air cleaner after you set the mixture, you'll see that the ratio goes rich to about 13.0-13.5 when you put the air cleaner on. It's amazing.

Oh, and I've got many hours on my sensor even when I use race gas (read: leaded), and it still works great.