Well, we always wondered about them A/F Monitors so we bought two of them from Jegs and brought them to the dyno with us. Well the dyno operator said not to waste our time hooking them up because they don't work. We asked him what his experience was with them and he said none bet he had heard that they were not much good. Well, we hooked them up anyway (heck we had around $100 bucks in them) and to his and our surprise they were right on when compared to the dyno printout. So we use them all the time for field testing. Here's what we do: We start by disabling the sec. throttel plates on the carb and make wot tests (they also work great for mid-range tuning) using the pri. side of the carb first. When we have that done we go on to the pri.and sec. at the same time. Workes just great. Oh we don't use the engines 02 sensor but weld on a seperate bung to mount the monitors owen 02 sensor.

Auggie

 

I keep telling people..they DO work. Maybe not with surgical precision away from 14.7 but plenty good enough to work off of.

FWIW disconnecting the secondaries liek that really isn't a good idea. It creates an unnaturally stong draw up top on the primaries...so even when you hook them back up the tune will be off considerably.

 

Well Jester you are partially correct (I have been useing A/F Monitors since 1989 when I bought my first one from K&N). When you tune the pri. side of the carb with the sec. side inop the only thing that I have observed is a slight lean cond. in the part throttel pos. at steady hwy. cruising speeds. The monitor will flash very rapidly between 1 and 3 lights, the third lite being 15.4 to 1 and the first lite being 16.9 to 1 . When I reactavate the sec's of course you are trying to lite six or seven lites (13.3 to 12.5) for the whole carb which is much easier to tune then the pri side by its self. Like I said before, when we tested them on the dyno they proved to be well wort the $ for jetting in all ranges. Its not as quick or safe as a dyno but it works.

Auggie

 

So, what brand are you using, and how much are they?

Ben

 

Well the last two I bought were from Summit. Summit sells there own for $27.95, but I use the Nordskog gauge for $35.95. I get my 02 sensors from NAPA for around $30.

Auggie