Ok here is the deal as i took my 71Z28 out for its first real highway run to help break in the motor. I got up to around 70 mph in fourth gear and the car would not go any faster even with the pedal pegged. But the deal is before i rebuilt the motor i pegged the speedo in this car and any with this year knows how high those speedos goes. any clues as to wh it wont go any faster?

 

I'd be very careful running it much until you've got this sort of problem figured out! Often times it can be just a timing issue, but it could also be a cam not lined up correctly, or improperly adjusted valves, either of which could kill a new engine if not properly adjusted.
Check everything you can. Valve adjustment, timing, and if those are good, then it's time to get deeper into the engine and pull the timing cover.
If the engine was professionally rebuilt, then you should go back to your builder and have them check things, or you could lose it before the warranty ends. I had one burn a hole in a piston back in the 1960's when I didn't get the valves adjusted properly, and it had the same sympton of not seeming to have enough power. What was really worng was a rocker too tight, which held a valve open and caused a big problem!

 

I would say 1971bb427 is right on the money. being a new engine I would definatley think internal verus a fuel related problem. approximately how many hours do you have on the engine? When we had cleggs do the engine in my dad's 56 they told him it needed a minum of 3 hours break in time before any hard throttling.

 

If I were you, before taking the car out again, I would look up the proper way of breaking in an engine to make your rings seat correctly. Don't go trying to beat the **** out of it right away, like you were attempting to do (burying the pedal at 70).

 

when I read the OP's first post, that was my exact thought

 

Ive drove the car for around 100 miles before taking it to 70. i just recently tuned the carb to reach around 19lbs per inch vaccum and timed the motor at just around 35-36. My compression is good getting proper fuel i think maybe a lifter is loose i have been hearing a clacking noise under the passanger side valve cover

 

A loose lifter wont cause the problem, unless it's REALLY loose! 100 miles isn't much of a break in period.
Your vacuum sounds a little low, as you should be able to run a little higher with everything properly adjusted. I'm running a pretty healthy cam and I run around 22-24 in. lbs of vacuum at idle. Did you install a new timing mark so you can properly adjust the timng? If not do you know if your distributor is set properly? Does it start fine, or crank slow when the engine is warmed up? Sounds like it might be a timing issue.

 

Its got a Comp Thumper Hydralic roller cam, roller lifters crane 1.5 roller rockers a comp double timing chain set. set at 0 and a msd hei street fire dist. Ive done 5 valve adjustments with motor running and also have a moroso gold u bolt stud girdle. I know the carb its enough though it only a edlebrock 1406 600cfm electric choke. Im running my vacumm for the dist off the closet line to the throttle linkage and that also were I used the vacumm gauge to adjust the carb with.

Cam specs are

Duration Advertised: Intake - 283, Exhaust - 303
Duration @ .050'': Intake - 227, Exhaust - 241
Valve Lift: Intake - .511, Exhaust - .497
Lobe Sep. Angle: 107°

 

yeah my 68 has an intake and exhaust duration of 293 and a 552 lift and when i had the timing set a 0 it with a 650 cfm edelbrock with the biggest metering rods and jets my kit had it still starved. once i advanced the time and switched to a 750 i had no problems. I would do what 1971bb427 is saying and recheck all of your timing. its easy enough to bump the distributor or move it a little bit when you are tightening it in place.

 

I'd have to look up the Edelbrock to refresh my memory, but I think the "ported vacuum" fitting for the distributor is on the passenger side. I'm pretty sure the drivers side port is manifold vacuum, which is what you were using to get your vacuum reading at idle while setting your timing. You can check with your vacuum gauge, and see if vacuum drops off when you open the throttle with that one. Then see if the passenger side vacuum rises with the throttle.