L98 rocker arms loose

[90coupe]

I just pulled the valve covers to paint them and noticed all the rocker arms are loose enough to wiggle side to side. I haven't owned a chev until I bought this Vette last summer so I'm not sure what to make of it. I ran the engine for about 45 minutes the day prior after having replaced the water pump, belt tensioner, and all the coolent hoses. (preventive maintenance with 72K on the car). The lifters seemed to take a while to pump up but it hadn't run for a few months. After it was running a short while they went quiet. Is this normal? Also, with the valve covers off, it would be a good time to put roller rockers on, maybe 1.6 ratio? But it is a speed density car, would I get any perfomance boost?
Thanks for any help or advice.

Ron

 

[offshore]

totaly normal. change oil and filter though. after several months of sitting the lifters will leak down. but they should pump up within 30 sec. old oil & a dirty filter will slow this up.

 

[vigman]

Adjust em!

Re posted for clarity!

Ya know I got dinged on this too!( rocker adjustment )

The one thing ya gots to remember.. is 4 rotations of the crank=1 rotation of the cam

So ya can get goofed up in the Correct initial line up of the cam. So lets review.

Firing order
1-8-4-3-6-5-7-2

( Stolen from GM book of wisdom )

Assuming a non running static adjustment

Adjust valves when lifter is on base circle of camshaft lobe ( the backside of the lobe ) as follows. And in a perfect world when your at #1 firing position on the crank.. and the cam's in the correct position.. the distrib's rotor will be pointing@ the #1 hole.


Crank engine to #1TDC firing position
( Piston UP both valves closed)..but if the valves for (#1 )are CLOSING as your coming up on the timing tab for TDC, you actually are in the #6 firing sequence. Rotate the crank 1 more turn.


So when your there #1 TDC
Exhaust 1-3-4-8
Intake 1-2-5-7

Now rotate ONE revolution and back to the TDC mark
Exhaust 2-5-6-7
Intake 3-4-6-8

As you adjust... you loosen the nut so you have just a pinch of play ( you dont feel the spring of the hydraulic lifter starting to load the pushrod ) take out the free play, and the BOOK states tighten 1 turn. some people say 3/4... other people state 1/2

So the threads are FINE and I believe 3/8 24 ( or 24 threads per inch ) so for a full rotation of the nut.. you've seated the push rod into ther lifter 1/24th of an inch... if you go half as much youve seated it 1/48 of an inch... So not a big deal here ( I go 3/4 of turn)

My .02


Vig!

 

[offshore]

If you need to adj. your rockers in a stock eng. with 70k on it you have a problem in the valve train.

 

[vigman]

Not true

Some BUBBA might have been in there ..helping.

or the orig owner just didn't take care of the care..and used to thin or to cheap oil

It will not hurt anything to adjust them back to spec.

Mike

 

[offshore]

hope that it's some bubba! if not. being a Hyd,/ roller cam.we'll you can guess the rest.

 

[90coupe]

Response to loose rocker arms

Thanks for all the advice guys. The top of the heads are really clean (good maintenance) I am running syntech 5-30 with fresh filter (change both every 2,500 miles). Previous (2nd owner) couldn't find the engine much less work on it. First owner I've been told was a Dr. (no bubba hopefully). So, my best guess is just adjust em and see what happens. I just don't know why they would all be loose to the point I can move the rocker around with my fingers. So, I have a weekend project, adjust the things. By the way, they are the stock stamped rockers and have pushrod guides. Are those stock? Any idea of the preformance gain if I put in some 1.6 roller rockers? Do I need new hardned pushrods and new guide plates or would the originals be ok?

Thanks again. As a newbee, it's great to get experianced advice.

Ron

 

[vigman]

Adjust what you have.

1.6's will give you a tiny change and change the power band a little.

Roller tips will decrease wear on the top of the valve stem.

Full rollers will make you change the valve covers for clearance issues, then you will need guide plates for the rockers being higher.

Hardened push rods are always a good thing.

Vig~