Lifter Knock 400CI

[nos2clutch]

I got a 77 trans am with a pontiac 400 in it. the top end was just rebuilt but the bottom end was left alone because it was in excellent shape. the heads were all machined and redone new edelbrock top end, cam intake and carb. I got it together to break in but when i started it there is a nasty valve knock on #8 intake i replaced the lifter and started it back up but its still sticking, i did replace the oil pump when apart and i have plenty of preesure on may gauge but the thing is still sticking. i have have done everything i can think of but nothing works. the rockers are pedestal mount so there is no adjustment on them i called edelbrock they told my to break it in like that, the noise started to go away after away but came back i have no clue. if anyone can give a hand it will be greatly appreciated

[N20LT4Bird]

Is there oil spraying up on the rocker arm? If not, maybe you have a blocked oil passage in the block that feeds that lifter....although if that were the case, your number #8 exhaust would probably be making noise also. Did you prime the lifters before you put them in? If not, the lifter may just need some time to pump up. The other possibilities are a bent pushrod or rocker arm.....

[nos2clutch]

i had swapped a rocker and pushrod from another cylinder and i get the same problem on the #8 intake and i do get oil to the top of the rocker and when i take the lifter out i have plenty of oil there too, when i built the motor all did to prime it was left the rockers alittle snug them took a oil primer till i got oil to all rockers then tightened the rockers down, so confusing

[N20LT4Bird]

i had swapped a rocker and pushrod from another cylinder and i get the same problem on the #8 intake and i do get oil to the top of the rocker and when i take the lifter out i have plenty of oil there too, when i built the motor all did to prime it was left the rockers alittle snug them took a oil primer till i got oil to all rockers then tightened the rockers down, so confusing

I usually pump them in a bucket of oil.....but I doubt thats the problem. Theres not much to it......youve got to find out where the slack is. If youre confident the lifter is being pumped up, and the rocker and pushrod are good and adjusted correctly, then youve eliminated the obvious.....I would begin to look at either a cam issue (not ground properly), or a valve issue. Rotate the cam so that the lifter is on the base circle and measure it's height in relation to another intake lifter on base circle, or....... Maybe there is an issue with the valve job....you should measure the installed height of the spring in relation the others......if its too short for some reason then that could cause some slack in the valvetrain....