Last straw. need help

[170-3tree]

Today we were screwin around with the 170 again with a re rebuilt carburetor from garenteed carbs of florida. They upped the jet size for us and it helped a little bit, but what i would like to do right now is try to provide a description of what is going on with the car. while screwing with the car today we adjusted the timing up to about 18 btdc and it started to gain rpms and smoothed out adjusted the carb idle air screw and it jumped from 500rpm to 700 with those two tweaks. I think that the best way to describe what is going on with the car is that it will idle really nicely for a few seconds then it will get rough and miss repeatedly on in no true pattern sometimes this will only last a second sometimes just as long or longer than it will idle nicely. We have replaced the entire ignitions system with no change and the carb has been rebuilt and rejetted twice professionally. we have adjusted the valves repeatedly the manifold vaccum is right at 18.5 in and the engine is in perfect mechanical condition.
I am out of ideas.
The only question i have is how much being bored out .040" and a fel-pro headgasket will affect the cr and if that could be the cause at all. i know the head needs to be milled, but is it possible that it could cause this?

 

[JackFish]

Timing at 18 degrees seems pretty high.
If so, you would be compensating for the increased rpms by overadjusting the carb.
Maybe try to get it running smoothly at say 8-12 degrees advanced.

 

[170-3tree]

We did that and it doesn't run smoothly at all it does the same thing, but worse. we set it back down and i adjusted the carb several times to get it a little closer, but it just doesn't compare. as of now we are trying the valves for the fifth time. there is no way to tell how to get these valves done right. We have a carb off of a 200 on the way and hopefully that helps a little. not even goin to lie i am getting so fed up with the car. going down the highway it just kinda jerks a little and i don't feel safe leaving town in the car most of the time.

 

[rbohm]

8) first thing to do is check the fuel pump output. you should 1/2 way fill a 20oz bottle in about 5 seconds or so, and the stream should be strong. if not you have one of two issues, perhaps even both;

a bad fuel pump
a clogged fuel line

either one or both can cause the intermittent problem you have.

 

[170-3tree]

Okay We have checked and the fuel is perfect. we adjusted the valves... again.. and got it running even smoother. it will need fine tuning in the future, but it runs a lot better. now i must figure out what rear end i have because i will need to overhaul that and in the future try to find a new 2.77 because there is a lot of play in the driveline past the engine. thank you for all input