Holley HP Steet wideband tuning

[Pyrotechnic]

I finally got my wideband oxygen sensor installed in my truck. The motor is 383 and the carb is a Holley HP Street 750CFM mechanical secondary.

As I expected by the smell of the exhaust, the truck runs has an AFR of about 12 at cruise anywhere between 30 and 65 MPH. However, when I accelerate to load the motor some to see how it runs when on the power valve, I get an AFR reading of around 14.

Is there something wrong here? Being that it is a double pumper I thought it would be rich all the time. I knew I would probably have to drill out the PVCR's after leaning out cruise AFR but right now it looks like they already need an increase.

[68GMCCustom]

I'm working on nearly the same scenario/same carb. Sounds like you need to lean up the primary side a jet size or two, and go a size or two bigger to fatten up the secondaries? Have you been able to watch the vacuum/MAP? Should tell you when PV is coming in? Why drill?

Hows tip in? WOT?

[Pyrotechnic]

Well that's the thing, I'm not even into the secondaries when it's going lean. This is a scenario where I'm rolling 65 MPH in 1:1 gear and I lean into the throttle to make the vacuum drop into power valve territory.

Well, at least I don't think I'm into the secondaries yet. Certainly doesn't feel like they are compared to when that motor is at WOT. I figure my vacuum would be zero if the secondaries were open?

[68GMCCustom]

0 or close to 0 at WOT. What a/f do you see at WOT?
it won't fix everything....but have you done anything with the accelerator pump circuits?

[prostreetC-10]

Be careful taking a drill to your carb. It is funny that your numbers are almost flipped around. You want somewhere in the 12.5 under load and perhaps 14.7 or higher at cruise. Those HP street carbs are not going to have a real big PVCR to start with. You can enlarge them to help you run a leaner 16 or so cruise A/F and still provide the needed bump under load. Do you have the right Hg rating on your PV? Have you messed with the jetting at all?

[nxtruck]

Not meaning to jack this thread, but, Pyrotechnic, where do you have the sensor mounted? In a primary or in a collector?

[Pyrotechnic]

prostreetC-10: I thought it was a little odd too that the numbers were opposite of what they should be. The carb is completely box stock, nothing has been changed on it other than setting the idle. I am not sure what the stock power valve rating is. I guess my next step would be to find out what the vacuum rating of the power valve is, then watch my vacuum gauge for when the lean condition happens. I'm thinking that should tell me if I have the right power valve for my engine?

nxtruck: it is in the exhaust pipe just after the collector.