vacuum& lifters

[dn123don]

i have a rebuilt sbc that runs real good,but if i sit in the drive,rev her to 5-6k rpm,on the way back down to idle the vacuum has a definite tick that matches a tick in the lifter/s. as it approaches idle it's fine. any thoughts

[adh383]

are u saying that you have a vacuum gauge that has a flutter on the way back to idle?

[dn123don]

yes thats what i,m saying

[Scotty_S-15]

Tick in the lifters? Whatcha mean?

Does it (they?) tick only after winging the throttle? Does it happen taking it to 5K in gear? Or, does it (they?) tick all the time?

........ What preload do you have on the lifters?

[smallblock283]

whats the oil psi at idel and at high rpm? you need at least 10 psi /1000 rpm so 5000-6000 60 +

[coppergmc]

You might be pumping the lifters up and causing the valve to stay open. You could possibly adjust the lifters differently and play with pre-load. Fast bleed down lifters or anti-pumps such as rhoads might help.

[dn123don]

thanks for the promt replies.but i think coppergmc nailed it. lifter/s are pumping up.the guy who rebuilt the motor said that he would correct the problem my fingers are crossed