I have a GM goodwrench 350 in my car (the 290HP one you can order from Jegs) , it runs great under light throttle at all RPM's but with anything more than light throttle it falls on its face and has no power. The engine is in perfect time and I dont believe that its missing when this happens, I think its something else. I mapped out my timing and if someone thinks it would help find the poblem I can post up the maps. I do have a 750 Edelbrock, could being over carb'd cause this much trouble? I pulled the plugs and they all look a little lean.

Is the accelerator pump working ok? When you pump the gas does it spray out the squiters?

Dave

could be other things but this sounds like a classic symptom of setting the timing with the vaccum advance still connected

Yes the accelerator pump is working as it should and trust me, timing is set properly. After a trip to jegs I'm back with 1446 rods and step-up springs, I'll give those a shot and report back, thanks for the suggestions so far.

Edit: got the new rods and plain springs installed and it runs great. All I need to figure out now is why it shifts at 4500 RPM's at WOT even though I have the weights that should make it shift at 5700(TH400).

I need more help, today I drove the car to work and it was doing the same thing, running so lean it was missing. Last night it drove great with the new rods and springs and then I parked it and this morning its back to its old ways with no changes. I pulled a few plugs once I got here to work and they indicate its really lean, whould I change jets as well?

first check for vaccum leaks, after that you will probrally need to change the jets to make it run richer, That mild 350 will probrally never run correctly with a 750cfm carb. Try and get a hold of a 600cfm

I had a coil do that to me once. Would idle fine, popped and spit with any load. Coil was weak, on it's way out. If your distributor is an HEI, I've had a bad pickup coil cause similar symptoms under loads on another car. It was most notable on hills, though.