Just did a cam swap and a buddies 03 5.3L

ew ls7 lifters and ls2 trays pushrods springs..........everything else for a swap
He has yella terra rockers as well with the cam

The instructions for the lifter say set cylinder 1 to top dead center and hand tighten the rocker bolts evenly making sure the push rods still spin slightly.
Did that^

Next it says to turn each rocker bolt 90 degrees and repeat, but make sure they don't turn past 360 degrees which wasn't possible to do for us.

Next tq all other rocker arm bolts to 22ftlbs

Any ideas why he is having lifter tapping/knocking?

 

pushrods aren't the right size. Ls7 lifter cup size is different than stock lifters

 

this ^

did you soak the lifters in oil for a bit?

 

we soaked them over night in oil.

The Ls7 lifters said direct replacement, butttt I know the seat is .05 taller than stock lifters < this is confusing

It just the number one cylinder tapping

 

You need different push rods buy a pushrod checker and check it I'm pretty sure that's the problem.

 

What length pushrods did you install?

How many degrees did you turn the bolt from zero lash to 22 ft-lbs?

 

Either wrong preload (wrong length pushrods), or possibly nicked a cam bearing.

 

Mine tap pretty loudly, especially when cruising, sounds like a diesel. Everything is new and my preload is around 0.075". My cam lift is only 0.561" and my springs aren't that heavy. Part of the game I guess.

But as mentioned measure for preload. I needed 0.050" shorted pushrods when switching to LS7 lifters to achieve the same preload.

 

he had 7.4s for the job

After hand tightening them I turned both bolts 3/4 of a turn, alternating every 1/4 turn.

 

I think its pretty hard to eliminate lifter tap in the LS engines. Mine has very slight tap and can only be heard when my engine is at operation temp. I've seen some big money, big name engines have some pretty noisy lifter tap when cold or hot. Makes me glad I did mine right and triple checked everything.