m6camaro

iTrader: (11)

Swapped in some PRC 5.3L 2.5 heads milled to 61cc chambers (I believe milled down .015) and tsp 1 7/8 headers and 42lb injectors on top of my LQ9 iron block 370. When I cranked her up, there are extremely loud tapping sounds coming from each valve cover. At first I thought the rockers were hitting the valve covers but I pulled the covers and they looked fine. I was told by TSP that my 7.400 comp pushrods would work just fine. The guy tuning my car used his push rod length calculator and he came up with around 7.375-7.390. Would a pushrod that is .025 too long cause such loud tapping sounds? TIA.

Bryan

Prerun4fun13

iTrader: (6)

did you let it run for a few min?? It will take a while for the lifters to pump up.

m6camaro

iTrader: (11)

Ran it under 2000 rpms for close to an hour. Sound did not get any better.

PREDATOR-Z

Calculator or actual p-rod checker.
What was the preload set at?
What size valve reliefs in your pistons?
and did you tune the 42s?

eallanboggs

iTrader: (1)

If that noise did not get progressively quieter very quickly and become close to a normal valve train sound within a couple of minutes the key would have been shut OFF. I certainly wouldn't have run it "for close to an hour" making a racket like that in hopes that it would quiet itsef down. It's going to smoke like hell and make enough racket when initially started that you have to grit your teeth, but it should very quickly start to quiet down the smoke should disappear. In less than 5 minutes the motor should sound normal and the smoke should be gone. What about your preload.

9t8z28

iTrader: (19)

Did you check the wipe pattern on the valve head?

Check the pushrods to see if they are rubbing on the head?