Running way lean

[Dan B.]

Did some tooling around in the ranger last night. At idle the wideband reads 13.5-ish which I think is good. Rolling down the road at a cruise (35-60mph) it is way lean (17-18). But at the point where I start to tip in the secondaries the AFR comes back to around 13.

The carb is a Holley 750 that came off a well built 302 from Mark Aubele on the board. I've got it on a healthy 351W. My fuel pressure is 6# from a Holley Blue through a Holley regulator.

So I'm thinking the idle circuit is fine, the primary jets need jumped up a couple sizes. When fully into the four barrel it stays around 14. That could even be fattened up a little to get closer to 13. So a jet change there also?

This wideband is awesome but I can see how it would drive you nuts!!

Your thoughts??

[TI Dyno]

should be 14.7 at idle and cruise at wot it should be 12.5 for NA 11.5 for boosted.

[SK@StreetLethal]

What is the primary and secondary jetting set at now?

[Dan B.]

Not sure. Out of town for a few days. Won't get back into the garage until next weekend.

[torqueboxer]

That carb is fine, dont do anything to it but maybe a primary jet change of one or two.

[Dan B.]

Thanks for the input.

[Mark Aubele]

Dan,

I had (well, Torqueboxer and I) set that carb up for an NA 302, making 347 at the wheels. I imagine you will need to step up the jet sizes at least a couple sizes. For the life of me I can't remember what we had in it, I know it wasn't set up square. I would try to get 14.5-16 at idle and 12.5-13.3 wide open. We made peak hp at 13.3, but backed it down to 12.7, lost 5 hp but I wanted it a bit rich so it would have a chance to hold together. Feel free to give me a call if you still have my number, if not PM me. I wouldn't go pounding on that truck WOT with it that lean.

[Dan B.]

I was just rolling around to visit family. Didn't go but maybe ten miles and not once over about 4K. I've got too much time into this thing to go melting it down.

I'll pick up a jet kit next week and start experimenting.

[somethingclever]

Get the primary's set up first and then start working on teh secondary's IMO. I would also lean out the idle a bit.