what would be best for my daily truck?

1 or 2 units with headers and duel pipes?

myself I wont go the cheapest but don't want the most expensive either so middle range on price is what I am looking for but also want it to work good and last. I have read about a lot of them failing but seem to be on the lower end of price range for them.

are they really that good for fine tuning in a carb?

skool me plez.

Innovate worked well for me

I have an Autometer 3579 (analog 2-5/8" gauge) which I find very useful for tuning. For example, I can see the difference between the common pump E10 and no-ethanol gas (about 0.3-0.4 AFR). I couldn't have tuned my Holley 850 without it (IAB, MAB, IFR, TSR, PVCR and of course main jets).

The replacement oxygen sensor that they sell for $120+ is actually a common Bosch unit that you can get considerably cheaper. The major problem with their design is that it is not tolerant of the voltage drop during cranking (it will never warm up and actually start reading). The tech line actually told me to put a switch in the +12v line and don't turn it on until after the engine is started. Which did "fix" the problem. Really great engineering there, guys

A more expensive one (than the Autometer that was over $200!) would have datalogging capabilities that are even more useful. You need some kind of wideband AFR otherwise you are just guessing from ET/mph (assuming you're even at the strip) or trying to figure out if a driveability bog, sag, stumble, etc. is too rich or too lean

Thanks Guys!

thanks DrCharles for the in-depth info. I don't need the data logging so I will have a look at the autometer one you listed.

and the tip on toggle switch for it. good info to have.

so the welding in a bung on the header collector is the hardest part of the install and has a +12volt power wire.

is the rest easy to wire up?

when you read the meter the higher number is lean? and the lower number rich? and you shoot for 13.5 - 14 or so?

and your right I am guessing on the carb tuning and why I wanted to try this afr meter set up. but I also need a learning curve on the common dummy level.

Two things, who measures the AFR during cranking? No one.
Why didn't you already have it wired in to a switched in run 12V?
I don't think the issue is Holley's engineering.

You are missing the point. I didn't SAY I was trying to measure cranking AFR. Good grief.

I ran power to my homemade dash gauges during crank and start positions of the column ignition switch. The voltmeter, for example, is useful that way...

And I DO think Holley/Autometer's engineering is the problem. Perhaps I need to provide more detail:

The gauge is supposed to enter warmup mode any time the voltage is below 12.5 volts, (AFR reading slowly moves between 8 and 10, indicating sensor heating), and once the O2 sensor heater is hot, it automatically swings to an actual reading. It even has an override input (to automatically start the gauge warming then reading) for cars without alternators where the battery is likely to be less than that during a run.

When cranking with the battery power directly connected to the gauge, with or without the override connected, the gauge stays in warmup mode forever. Whether the engine is running or not! That tells me that the dip to ~10 volts during cranking confuses it for good - since once the engine starts the alternator is charging at 14 volts. Confirmed on the dash gauge and with external meters.

The ONLY way to get the gauge to work is to start the engine, THEN close the additional switch to the gauge power once the batt voltage is above 12.5 volts. If the gauge won't work at 10 volts, it should automatically reboot once it has 12.5 volts or higher. As clearly stated in the spec sheet. So that is crappy design.

Installation problem, pure and simple.

Quote from the installation instructions



Nowhere does it say to hook to a source that is hot when cranking.

Link to instructions

https://static.summitracing.com/global/images/instructions/atm-3579.pdf

Furthermore, the instructions say, if you bother to get down far enough to read the Sensor Control Mode section, that 12v is the minimum voltage needed for the gauge to work, but it will not turn on the heaters until the voltage is above 12.5v. As that tells the gauge the alternator is on.

Your switch setup is designed to be used in a race car without a charging system, not as a crutch for improper installation.

So you can either connect your power source to a hot in run only connection or continue to think you are right and Holley is wrong.