02sierraz71_5.3

iTrader: (2)

good find bill
preciate it, should have done more research oh well live and learn

BigTex

iTrader: (16)

I wouldn't worry with the term 'preload' at this point. Our stock rockers aren't adjustable, so as long as you get pretty close with the geometry, you'll be OK. My cam has a very similar lift and I'm running 7.4" pushrods. With a .050 mill, the 7.35" rod would be my choice, so I think you've got that right. You really can't adjust the stock rockers, you just need to make sure you've got them torqued down properly.

Its possible the loose rocker bolts could have caused damage with everything wobbling around.

Kano

iTrader: (3)

whats the base circle

the smaller the base circle the longer pushrod you need right?

02sierraz71_5.3

iTrader: (2)

I didnt think about damage caused by those rockers wobbling.
What damage do you think could have been caused and what sort of tests could I do to determine damage and extent?

I really think the valve sound comes from improper valve geometry/preload as a result of the shorter pushrods. I could be wrong though

Kano

iTrader: (3)

Id pull it back apart and visually check everything

Id take bigtex's advice and run the shorter ones
make sure there torqued down and use loctite

if I remember right
I torqued mine down spun it by hand several times
then retorqued them with loctite

I dont know about the stock ones
you dont want it to bottom out in the lifter
and bend

02sierraz71_5.3

iTrader: (2)

Im going to call comp tomorrow and see what they say, they'll probably tell me to buy a length checker
Ill post up the outcome I plan on taking care of it myself tomorrow, if I didnt have to depend on other people this would of been done right the first time.
I hate not having time to do ****.

marc_w

I thought I recall that the amount that you mill off the heads, isn't directly what you want to take off the pushrod.

Off to search...

marc_w

Well, here is a good place to start to see how things look:

http://www.holley.com/HiOctn/TechSer...ECVTTech1.html

02sierraz71_5.3

iTrader: (2)

I think I remember reading something witt1 posted about a formula to figure proper length. Ill see if I can get his input

BigTex

iTrader: (16)

The info in the link marc posted isn't for our engine type. There isn't any way to install a solid lifter w/o removing the heads. Its also using adjustable roller rockers.

The beautiful thing about our hydraulic lifters is their forgiving design. During operation, they are pumped full of oil and automatically adjust to the valvetrain components (within reason). If your pushrod length is close, the lifter makes up the difference.

length - lowering the rocker mounts by milling the heads is a direct relation to the pushrod length. Cam lobe lift and valve lift is related to the rocker ratio. a .050 mill of the head would call for a .050 shorter than stock pushrod. Stock is 7.38". Most cams have a smaller diameter base circle thats usually related to the increased lobe lift. A rough guess would have the cam radius .030 smaller, which on stock heads would call for a longer pushrod. Take the 7.38 stock length adn add .030 for the smaller cam radius and you'd need a 7.4" pushrod. Then subtract .050 for the milled heads and you'd be at 7.35", which is what he's running.

Worse case, say the mill and base circle cancel each other out, and you need a stock length 7.38" rod which isn't available in the aftermarket, so just put the stockers back in.

Damage - it could have caused a number of issues. Think about how much power the motor is making and the tremendous force thats directly applied to the camshaft. That rotating torque is transferred to the lifters, pushtods and rockers to open the valves. If the rockers were loose, all that force would be going at all different angles from the pushrod applying stress to the rocker. Factor in rpms, and you've got a problem. You could see bent pushrods, rockers bearing problems, bent / cracked rockers, bent rocker bolts, stripped / cracked rocker threads in the head, etc...

Take the rockers off and check each one and check the pushrods at the same time. I'd also double check the head bolt torque readings since the installer was incompetent.