Engine Knock/Power issue

[Kixwy2]

Hi everyone!

I am new here, and very glad I found this forum. I bought a 1974 GMC truck several months ago (my first!) and am loving being a truck owner! I have some pics at the welcome page for everyone. So, I knew the truck had some issues when I bought it, and am trying to get those sorted out.

Ever since I have owned the truck, it seems to have no real power on acceleration. It goes, but it doesn't zoom, like you need to when you get on the freeway in CA. I looked under the hood, and realized that with the vacuum advance hooked up, the distributor reversed direction. So I tore apart the distributor and discovered it had one weight, and it was reversed.

That got replaced.

I have also replaced the spark plugs, wires, cap, coil, rebuilt the carb, and plugged up the extra vacuum ports on the carb. Even though this is a 1974 350, not needing to pass smog, it's a CA truck and has emissions gear like the EGR valve. The EGR is busted so it's just sitting there plugged up until I replace it or block it.

At the moment, it's timed at 12 degrees BTDC, which is CA standard, but I get this bad engine knock when I try to climb a little incline or accelerate hard. If I let off the gas, it goes away. This is all well and good if I am driving in 5pm traffic, not so good if I need to get on the freeway.

Any ideas? What am I missing or doing wrong?