Could REALLY use some help here.
A couple of weeks ago my LSI lifters went south and scored my cam. Long story short, replaced cam
(224/228/581/588) and installed new LS 7 lifters and 7.4 rods.
Started the car up and ( if you can remember that far back) it sounds like an old noisy typewriter.If you can't remember that far back, it sounds really bad - tap,tap, tap...loud.
I know how to adjust lifters on the "old" Chevy engine but I'm told
"there's no adjustment on the LS1 valve train - you just torque it to 22 ftlbs"
When I do a search on LS7 lifters all I come up with is "one or two turns past zero lash".I know what zero lash is but how do I "play" with that 1 or 2 turns to quiet this thing down?
Can someone, anyone, PLEASE give me an "LS7 lifter adjustment procedure FOR DUMMIES" ?
I'm REALLY losing sleep over this thing.
Thanks for any and ALL help.

 

Valve adjustment procedure???????

Unless you have an aftermarket rocker arm set up,,,,,,,,,,,,there are NO adjustment that can be made to the valve train.

You torque the rocker pedestal bolts down to the torque spec 22ft/lbs and thats it.

The lifter preload/adjustment is done (on a stock valve train set up) by lengthing or shortening the pushrod.

Did you check the push rod length by using an adjustable pushrod? I know 7.40 pushrods normaly take care of most cams but, unless you check the actual required length, that could be the issue.

Are you sure that you dont have a damaged roller rocker or spring?? The roller rockers are KNOWN to puke out the roller bearings. Give all the rockers a very close inspection.

Bill

 

In addition, LS7 lifters are approx. .060 longer than LS1 lifters when measured at the cup seat.

 

Why two threads for the same subject?

 

I agree with Bill's suggestions, but I don't with this ".060 longer" statement. ALL LS engine replacement lifters will be part number 17122490 from GM. This is for LS1, LS3, LS7 and LS9. The difference over the years in lifters are given here; Anatomy.

 

Link to how to check pushrod length: http://www.ls1tech.com/forums/11606269-post19.html

 

I don't like just "torque to 22ft/lbs" and call it good. Seen a lot of noisy valvetrains that way. Adjust each rocker to 22ft/lbs when the lifter is on the base circle of each lobe. You get a even adjustment across the board and it will run quieter.

More time consuming?? Sure. But worth it IMO. Get a starter trigger ($15 at the big box parts stores) or get a friend to key the motor over as you run through the rockers.

 

Most of the after market cams out there run a smaller base circle than stock..7.4" pushrods is what they all recommend and still work fine, but you have a little more noise from the valve train..A switch to 7.425" pushrods will help quieten it down...

 

Put a cylinder at TDC and check where the roller tips contact the valve stem on both valves (while the lifters are bled down). They should be middle - slightly towards the intake side of the valve (center line of the block). If they are too far towards the exhaust (significantly past the center of the valve stem), your pushrods are too long. Too far the other way and your push rods are too short. Either condition will lead to a noisy valve train.

 

[QUOTE=lucky131969;1571008915]Why two threads for the same subject?[/Q

Believe me, I don't know how i did that and iI can't figure out how to delete the second post.
Bill, I don't think it's a single rocker because its several (many? all?) of the lifters on both banks that are making the typewiter sound - its really more like a cross between a type writer aned a rapid fire machine gun.
I hope my mechjanioc knows how to preload the lifters and how to check the rod lenght. The thing is this is the same cam and the same rods that were in there originally and the valve train was super quiet.
Confused because some treads make a thing about the LS7 lifters being "longer" and some treads say they are "a diect replacement (that's what GM says)".The springs are brand new and are installed properly.

 

This is worth checking again. Make sure the new valve springs are not going into coil bind. This can not only make a lot of added valvetrain noise, it can cause valve stems to break. What brand and type springs were installed?

 

Check this thread:

http://forums.corvetteforum.com/c5-t...ad-please.html