Very Low Preload #'s - sound right?
Very Low Preload #'s - sound right? We just did a head/cam install on a 99 LS1. Used a set of unmilled patriot ported LS6 heads, stock rockers/lifters and a 224/224 581 lift cam with XER Cam and factory gaskets with 7.40 pushrods. The car is down on power and the exhaust sounds like a tractor trailer at full throttle. I just checked the preload and all the exhaust valves only have 1/4 turn to get to 22lbs past 0 preload (using EO/IC method) and Intake are all at 1 full turn past 0.
What caused the preload to drop that far?
Is it usual to have a different preload on exhaust/Intake?
What pushrod lenght should we go with?
What caused the preload to drop that far?
Is it usual to have a different preload on exhaust/Intake?
What pushrod lenght should we go with?
Staging Lane
Joined: Dec 2008
Posts: 79
Likes: 0
well your exhaust preload would be.012" by that method. a 7.45 pr would put you in the ball park. your intake is .047" now, which is pretty close to spec, 7.45's would put those to .097", which some say is hi and some say will quiet your valvetrain.
im working through a similar issue now my self.if you can get a dial indicator you can measure your preload a little more accurately. i know if you end up with to much preload you can damage your valvetrain, collapse lifters, and even burn up valves and seats.
let me know how it goes, my car seems down on power and even seems to loose lope once the engine gets really hot and expands.
im working through a similar issue now my self.if you can get a dial indicator you can measure your preload a little more accurately. i know if you end up with to much preload you can damage your valvetrain, collapse lifters, and even burn up valves and seats.
let me know how it goes, my car seems down on power and even seems to loose lope once the engine gets really hot and expands.
