Wideband AFR tuning a carburetor

[Supercharged111]

Cool. The 4150 EFI systems are just too hit or miss in the reviews. For a ‘bolt on and drive’ setup it sure seems like a lot of unexpected difficulties are out their with less than stellar tech help. My intake has cast-in injector bungs so if I go ahead with EFI it will likely be multport and me tuning it. That would be better anyway and not a lot more expensive.

Bolt in and go is a marketing claim. My neighbor tuned one and it looked damn simple to me. Took a bit of fiddling to get the IAC just right and the tip in fueling, but it turned out great. He's not what you'd call a hot rodder either, but he has tuned carbs before.

 

[Supercharged111]

I’d think one of the hurdles to overcome when adapting an afr to a carbureted vehicle is where to put the o2 sensor without a factory location? If it’s going to be permanent you’d probably need to weld on a bung. Does the gauge come with something like that?

I'd hardly call it a hurdle. Permanent or not, the only way to avoid welding is to get an AEM clamp/bung.

 

[Supercharged111]

I get it, but if a bung is your mt Everest you've chosen the wrong hobby. ANY exhaust shop can handle this if you don't have a welder.

 

[Boglog]

I get it, but if a bung is your mt Everest you've chosen the wrong hobby. ANY exhaust shop can handle this if you don't have a welder.

I was just trying to bring it up, didn’t realize you were such a bung expert.

 

[Supercharged111]

I was just trying to bring it up, didn’t realize you were such a bung expert.

Words mean things. I would have addressed it as "something to consider" as opposed to a hurdle, but that's just me. Yes, I do get hung up on semantics.

 

[Boglog]

And just that when you buy a gauge it’s not going to come with everything you need to put it in.

 

[Supercharged111]

And just that when you buy a gauge it’s not going to come with everything you need to put it in.

Eh, some do some don't. Gotta figure the wiring aspect as well. For stuff like this, I prefer to run my own accessory relay. In my truck, I power the aftermarket gauges, wideband, and a few other things off of this relay. Easier and cleaner than tapping off a million other things and hacking the existing harness to death. I think my AEM came with those ghetto *ss vampire taps for install which is OK if you're still in high school. They also don't include a gauge mount/bezel/etc so there are a number of things to consider. You can also get wideband controllers without gauges, they just talk to a datalogger, but I like having a gauge to look at to alert me to something that's gone wrong.

 

[pontiacgp]

Yes, it's like a cheat code for tuning a carb. Set the main jetting, move onto needles (Edelbrock), do secondaries and done. It idled stoich all the time, cruised stoich, stepped up around 13.5-14:1 on primaries and secondaries took it down to 12.9:1. Every time, no matter the weather. Only reason I ditched it for EFI was it boiled fuel like mad and would leave me stranded. I tuned a friend's Holley and it didn't seem to have that big a range of AFRs, i.e. cruise with no stink then floor it and have all the fuel you need.

with no map sensor to measure air density among other things a carburetor would not have the same mixture with changes of weather

 

[Boglog]

Eh, some do some don't. Gotta figure the wiring aspect as well. For stuff like this, I prefer to run my own accessory relay. In my truck, I power the aftermarket gauges, wideband, and a few other things off of this relay. Easier and cleaner than tapping off a million other things and hacking the existing harness to death. I think my AEM came with those ghetto *ss vampire taps for install which is OK if you're still in high school. They also don't include a gauge mount/bezel/etc so there are a number of things to consider. You can also get wideband controllers without gauges, they just talk to a datalogger, but I like having a gauge to look at to alert me to something that's gone wrong.

Yeah those “vampire clamps” are kinda ridiculous, a common source of problems. Good advice.

Although most don’t have a data logging feature I’d imagine for tuning a carburetor a single wire (non-wideband) afr gauge may be sufficient and 1/2 the cost. What do you think?

 

[Supercharged111]

with no map sensor to measure air density among other things a carburetor would not have the same mixture with changes of weather

I expected a change in AFRs in the winter, but did not observe any. Also, I do not see a change in MAP from summer to winter on my laptop (for my EFI trucks) either. Doesn't make sense to me, but this is what I've observed.