8secbusa

I really am looking for some suggestions on diagnosing if I have a lifter gone bad, or worse, a bearing issue.
Here are the symptoms:
1) Keep getting random misfire code on my predator after 5-10 minutes of easy driving or 1 hard roll through the gears
2) GM Tech2 scanner showed #7 with a few misfires at idle, then if I rev it hard from idle, up to 6K, as soon as I cut the throttle, the misfire count for that hole starts jumping up rapidly.
3) The motor revs ok, but has a bit of a mis at about 5K-6K

I have pulled all the pushrods (they are already upgraded) and they are not bent.
I check the valve lash, all ok ( I run 1.85 rockers and have them about 3/8 a turn preloaded

I was going to pull the heads and replace the lifters, but want a little more assurance that it is the problem.


Thanks

99z28monster

iTrader: (3)

well I had all of the same issues as you, I was lazy and just ignored it and turned the mil lights off. So now I have a ruined cam, and three smashed up lifters. One of the lifters is so bad that it is stuck in the block and I am gonna have to pull it from the bottom. So I would say it's better to play it safe and replace the lifters now before something major goes wrong.

JPH

iTrader: (2)

Your "small" DRY N20 shot bothers me, and it's on #7 cylinder also.(the one thats always the leanest)