...spits,sputters,and backfires through carb and exhaust above 2500 r.p.m.

[clicker]

Is this a vacuum leak or what? Have checked as best as can for vacuum leaks. The motor runs fine at idle, and up to 2500 r.p.m. It spits,sputters,and backfires through carb and exhaust above 2500 r.p.m. Have checked valve clearence,have checked points gap. Could this be a faulty distributor cap? Has Weber carburetor. Seems like something is holding it back.

[GTJIM]

"Spitting Back" is usually caused by lean mixture or no spark advance.
Check manifold leaks - more likely at closed throttle when vacuum is higger though
Then ensure that the fuel pump is delivering enough fuel and that the float level in the carb is set correctly.
Also check that the distributor is not gummed up or jammed.

HTH