just added edelbrock 2101 intake to my 305 manual 3 spd. also add msd dist,headers, lunati cam and 1405 carb.these perf upgrades added the extra power i expected with one side effect.whenever i go up past 2500 rpm or come down past 2500 rpm, the valves seem to clatter.i've everything from octane booster,to changing rod jet spring combos.same problem graemlins/clonk.gif

What valvel springs do you have? What cam?

Sounds like ,the springs are not doing the job. :(

the springs are cranes performance h-11,with a lunati cam with a 248/254 duration, .458 lift.the more i drive,the more i am begining to doubt this is actually valve clatter, i mean, it idles is sweet and i can push 5000rpm with ease and no clatter.what i can't understand is the clatter when i come down past 2500 rpm.

what about fuel pump lever, or fuel pump push rod, do you have a cam button touching the timing chain cover?

i thought i had a hard clatter problem but it really was a knock problem.i thought my engine noise was caused by a lean condition, but after trying every rod jet combo that came with my #1479 cal kit i thought otherwise, until i discovered a rod combo in a differnt kit. kit# 1489. WHICH IS FOR A 1411 CARB CALIBRATION.i ended up buying two different cal kits for a total of about 90 bucks.after installing this cal combo and adjusting my idle mixture to run richer,which slightly affects off idle mixture my clatter knock problem is no more.thanks to everyone who answered this post.