ls1 monte

I have a issue with rockers or lifters. short block has 150k on it.startup is fine but when u drive it and it gets to 160 degrees, it sounds like the rockers are backing off Running like the valves are not opening all the way.pulled the covers and rockers are fine. oil pressure is 15 at 900 rpm and 25 at 2000 and 45 at 3500. i just put new ls7 lifters in it 2 days ago and made it worse its happening at about 145 150 degrees. If i let it sit still for a couple minutes it comes back to normal while idleing as soon as i go a minute or less its back.

any help would be great thanks.
Junkyard lq9 all stock new oil pump from gm. cam from tsp around .580 lift. l92s with springs for the cam gm 5 layer head gaskets. victor jr intake aed 750 cfm. and 3500 stalled jw400.

ZONES89RS

iTrader: (25)

Sounds like the wrong length pushrods maybe(too short), when the oil gets warmed up the lifters are not primed much at idle.

Your oil pressure sucks ***** as well, mine is 45 PSI on a used oil pump at 800 RPM idle and goes to 80 PSI in the revs above 3500 RPM.

brandoz28

iTrader: (3)

definitely check out that oil pressure issue, and check the pushrod length.


what weight of oil are you running?

3pedals

iTrader: (3)

sounds like some wear in the crank/main/rod bearings thats causing low oil pressure. I would consider trying 10-30 oil, or even 20-50. if that quiets it down and makes it run normal, you'll know the bottom end is loose, and re-fresh is due.

ls1 monte

im running 20w-50 now and with little change. all day today its been running 25 psi at 1000 and gose up slowly from there to 50 at 4000. i ran the motor to 6500 on a pass comes up to 65 70 psi under full load . so most likely bottoms worn out. but pushrods how do i check if there rite?

ls1 monte

i know how to check the lenght sry being a noob.

ZONES89RS

iTrader: (25)

Well, also, what oil pump you using? The stock truck pumps are know to stick open for some reason after a cam swap on the bypass, might be it unless you replaced it.