You can't just go loosening or tightening your valve lash "willy-nilly" (I've been waiting for the right time to use that technical term). ;)
It's no wonder your engine is running crappy.
Read this: Valve Lash Adjustment

I did that once on my 427,thought I threw a rod or something cause it sounded terrible.:D
I missed a shift at high rpm while slamming gears and a pushrod went right through the rocker arm.
It was a bowtie Corvette L89 solid lifter cam with stamped steel rockers.

hahah, well the thing is we did tighten all the valves down to the stock specs, and installed a stud girdle to hold them. Its just I cant figure out why it would back fire so much through the driver side exhaust:rolleyes:

So you did follow a procedure then?
I prefer to use the procedure as shown in the link I gave.
I've adjusted valves before going by how the Motor's books says, at TDC setting certain ones I-E-E-I....etc., than rotate 180 degrees and do the rest. I always would end up having some that were either too tight or too loose. If you set yours that way, try turning the engine over by hand bit by bit while checking the rocker arms. See if you don't get a few that feel loose. In my opinion, the "two-step" procedure is good enough to get the engine running, as long as you intend to perform the "engine running" adjustment. Otherwise, it's not nearly as good of a permanent "static" adjustment compared to the "valve-by-valve" way.

I followed the procedure of TDC, when motor assembly was going on, according to a motor book, Ya know I ran it with passanger side cover off and thats how I found intake #4 some how wasnt lifting, Im going to take off the driver side here in a day or two and check all those lifters, more than likely doing the whole process over again, all i can figure is maybe a few studs didnt get adjusted right at tdc. The motor is very tight specd with in .010 on about every aspect so just a small amount off tdc esp with a hydralic cam, hydralic roller lifters, and 1.5ratio hydralic roller rockers, can cause problems as you know.:cool: This is my second performance motor Ive built. the first was a 289 Ford that I got 380hp out of. But ford motors arent very realiable, from my point of view:eek:

I have been called to many a friends house because their new motors would not run or did not run right, Most of the time is was either firing order of the plug wires or valve adjustment.

You realize valve adjustment needs to be right? do you know how far a valve has to be out of adjustment for it to show on a compression test? You are either doing something wrong with your adjustments or you are re-using adjusting nuts that are not suppost to be reused. If I had a customer with one valve that far off I would strongly recommend re-setting all the valves, unless you know why the one was so far out.

Another thing is, how are you determining zero-lash?
If you are spinning the pushrod as you tighten the rocker arm nut, you could be getting a false reading (still feeling loose when it really isn't). Rock the pushrod up and down as you slowly tighten till you feel zero-lash, then tighten the final 1/4~1/2 turn.

Just a update, I adjusted all the valves properly still had a backfire issue, so i changed carbs from a 600 electric edelbrock to a carter afb 650 electric no change still back fire, installed a fuel pressure regulator no change, checked timing set it at 8 before no change, checked spark on plugs 6 & 8 both stopped firing for a 1 sec to 1.5sec intervall on a decel throttle, so i sprayed carb cleaner by the cyclinders on the intake to check for a leak nothing. right now ive noticed a few plug wires are getting warm from the headers but nothing really bad.

I just cant figure it out. Any more suggestions?:confused:

Alright so now Ive determined that running a hydralic lifter cam with hydralic lifters and roller rockers means, the best way to adjust valves is to do it while the engine is running. Which i plan on doing tomo. So lets hope it works.:D

So I did 5 valve adjustments with the engine running and it still didnt cure the backfie, it made for a very precise adjustment though, BUT i did find out my problem and it was caused by a simply mistake that was an easy fix like always:D..... The backfire was caused by number 5 and 7 cyclinder plug wires being crossed and number 6 cyclinder plug wire not connecting tight enough on the plug. Now i have the full power ive been looking for in this motor:cool: