eb02z06

iTrader: (18)

Okay guys all the tech guru's needed here. Now say I have a pair of ported LS1 heads with aftermarket valves( l'll keep the manufacturer out of this sisce noone can get a hold of him). The heads are not supposed to be milled or anything but noone knows for sure. Now we are still using the factory rockers and lifters and a typical comp cams XE grind cam, block is a LS6. Now apparantly the head porter usues a aftermarket valve that is longer or shorter-again noone knows for sure. Now in order to get the exact valvetrain geometry we can either shim the rockers or get a different length pushrod. Well we don't want to us shims so we will get the right pushrod. According to Chevy we want to bolt down the rockers to 22ft/lb's once we hit zero lash. Now on a 5.0 mustang with non-adjustable rockers, after u get zero lash you should hit 17-20ft/lb's within 1 turn. If not u can either shim or install a different length pushrod. Now my question is does this theory also apply to the LS1/LS6 engines? Another thing i did notice is that if a put a straight edge along all the valve tips there is a difference in height between the intake and the exhaust valves-say about .060. So my friends how do i check for proper lifter preload and get perfect vlavetrain geometry-I hope this question made some sense-thank you!

gollum

iTrader: (1)

Some engine builders say the correct lifter preload is 3/4 turns till tight, past the point where pushrod cannot be spun between fingers. This can be corrected with different length pushrods.The factory adjustment is 1 1/2 turns until tight.


The geometry question is one I have not given much thought on. COMPCAMS, CRANE etc. can help you with setting your geometry correctly while obtaining correct preload.

bigdsz

iTrader: (1)

Do you have stock or dual springs? When you say you can't get a hold of the porter do you mean Jay? If it is Jay I know on my heads he suggested 7.350's.

I think he uses a longer valve for the 977 or 978 springs.

eb02z06

iTrader: (18)

Yes Jay's the man but he told me 7.4? That turned out to be .096 though preload.