backfire @ 2300 rpm?

Ok so I just installed a weber carb. my truck fires right up, but backfires at 2300 rpms every time. I havnt made any adjustment, so I figure its running rich. The question I have this. Would to much gas pressure cause this? I have seen others on this forum make suggestions to reduce fuel pressure for various problems. Thoughts?

If it's dumping too much fuel that could cause some backfire. My haynes manual says these pumps do 4.6 - 6 psi. I'm putting this regulator on there to dial it down.

Does the backfire happen if you're just revving it or does it only occur when you're driving?

So far I havnt really driven it, I have a huge oil leak from the valve cover gasket. It blows oil directly on the exaust manifold... I have one on order so I should be able to drive it soon to find out...

So I got the backfire problem worked out .. The truck purrs like a kitten... But I still have smoke pouring out of my oil cap. Now it seems to me if my rings were that worn, my engine would run like crap. Is there any way I could be getting exhaust blowing up that way? Like when I take the oil cap off, it's under a lot of pressure... Could it be some bad gasket?

Thought I'd chime in is this a 2.6 or 2.0 that smoke coming out the oil fill cap would indicate bad rings but pressure
Can bulid up in the crankcase if the PVC is bad its possible the head may have a crack in it
I'd check the PVC first if that checks OK run a compression test I've had cars with alot of blow by and ran great hope this helps.

Thanks. It's a 2.6