Carb Question

[Hugh Mongus]

I have an Eddy 600cfm carb. I recently changed the cam and installed vortec heads. My carb was set properly prior to these changes, and now it is too lean at WOT. Should I change the metering rods or the jets first to fix this? I don't wasn't to start swapping things around and get things all out of whack.

My guess is the metering rods first them larger jets but I would like a little reassurance.

thanks

[Wrenchbender Ret]

Yes. I would try the metering rods first. They are easy to change.

[davepl]

How do you know it's lean at WOT? Dyno run with wideband O2?

If you're reading the plugs, you have to kill the engine as soon as you lift if you want to check what the mixture was like at WOT, because if you coast down and stop you'll be reading the mixture for coasting down and stopping...

Presuming it's all on the high end then it'd be metering rods. If anything the cam would make the engine less efficient down low, so the jets might need to change but likely not larger.

If you have a chassis dyno in your area, that's the way to go.

[Hugh Mongus]

Assume it's a lean issue since it pops and cuts out when I romp it. Cruising speed is fine, and slowly increasing throttle is fine. Just doesn't like heavy throttle. I adjusted the pump to give a larger shot and it seems to help a little, but not correct it completely.

Should I be looking at something else?

[Lattimer]

Usually more cam needs more accelerator pump. On my Street Demon it worked fine on my stock 327, but my 355 with lumpy cam needed a ton more squirt. Adjusted the linkage all the way and went up 2 sizes on the nozzle to correct it.

I did not change rods or jets.

[davepl]

Originally Posted by Hugh Mongus

Assume it's a lean issue since it pops and cuts out when I romp it. Cruising speed is fine, and slowly increasing throttle is fine. Just doesn't like heavy throttle. I adjusted the pump to give a larger shot and it seems to help a little, but not correct it completely.

Should I be looking at something else?

Really sounds like accelerator pump. Once it's done its bog or cough or whatever when you floor it, does it then sort itself out?

If its only lean for 3-5 seconds after you floor it, that's accelerator pump. If it stays lean, that's calibration/jetting.

Of course their could be more exotic problems, I'm just keeping it simple.