Club Cobra - air fuel meter

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Hi Michael,

I mounted a vacuum gauge and an AFR gauge under my dash. For me it was the best thing I ever did to tune the carb. I used to have to get the car emission tested, and with the gauges I was able to tweek the carb and distributor to get it to pass emissions every other year instead of paying someone to do it. With the AFR gauge you can instantly see the results of everything you do to the carb without relying on feel, or sound, or plug reading etc. I highly recommend it.

Sydney

When you datalog AFR for a carbureted engine, your heart will stop. The curve is not smooth, and, at least initially, changes are not intuitive. Go to Engine Masters Season 7, episode #6, and you will find a dyno test of an LS3 with a 950 CFM XP Holley.

The EM guys give an excellent run down on how to tune your Holley for your engine. While a chassis dyno makes it easier, it can also be done in car on the road, preferably with an extra set of hands.

Watch the vid, and I think you will get excellent guidance on a relatively simple process that has long been hidden as black magic in a dark corner of the garage.

BTW one of the things you will notice is the difference in power between an out-of-the-box carb and a tuned carb is around 1%, but, and this is a big but, the engine's driveability and, most importantly, longevity will be substantially improved.

In the FWIW bucket, you should run two wideband sensors, one for each bank and a data logger to avoid getting accidentally ambushed.

Enjoy the vid ...

Definitely buy a wide band sensor/gauge and do either a permanent or temporary install! I did a temp install (replaced my clock) and it has been very valuable in improving the mixture ratio on my Weber carbs. Some day I might even put the clock back in!