Rocker preload
Thread Starter
Staging Lane
Joined: Feb 2002
Posts: 60
Likes: 0
From: Atlanta, GA
Rocker preload I've got a set of MMS 5.3l pnp heads and a 229/229/112 LSA cam that I'm installaing on my 2002 C5. 4 rocker shims, .020" thick, came with the setup. I need to establish between .030" and .050" of preload. What's the best way to measure the preload height?
TIA
TIA
Re: Rocker preload I don't know why they do that with the shims <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />
You would be better off with the right pushrod lenght in the first place. Anyway, here's what to do.
Bring the exhaust pushrod on any cylinder up until it is at it's peak. Install pushrod on the intake and bring the rocker bolt down until there is no play (zero lash). Now count how many turns of the bolt it takes to completely tighten the bolt. Should be 3/4 to 1.25 turns for acceptable preload.
Mikey
You would be better off with the right pushrod lenght in the first place. Anyway, here's what to do.
Bring the exhaust pushrod on any cylinder up until it is at it's peak. Install pushrod on the intake and bring the rocker bolt down until there is no play (zero lash). Now count how many turns of the bolt it takes to completely tighten the bolt. Should be 3/4 to 1.25 turns for acceptable preload.
Mikey
Thread Starter
Staging Lane
Joined: Feb 2002
Posts: 60
Likes: 0
From: Atlanta, GA
Re: Rocker preload Thanks, Mikey.
MMS sent me the Comp Cam Hitech 7.350" pushrods for this setup. When I asked Mike Morgan about the shim kit he said, "Sometimes the 229 will need two to get the preload just right. You want to see about .030 to .050” preload." When I initially spoke with him about the pushrods, he indicated the 7.350" are the correct length. I guess not?
I appreciate the quick response. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
MMS sent me the Comp Cam Hitech 7.350" pushrods for this setup. When I asked Mike Morgan about the shim kit he said, "Sometimes the 229 will need two to get the preload just right. You want to see about .030 to .050” preload." When I initially spoke with him about the pushrods, he indicated the 7.350" are the correct length. I guess not?
I appreciate the quick response. <img border="0" alt="[cheers]" title="" src="graemlins/gr_cheers.gif" />
Thread Starter
Staging Lane
Joined: Feb 2002
Posts: 60
Likes: 0
From: Atlanta, GA
Re: Rocker preload That's why I asked about the pushrod length before I ordered. Aren't pushrods sold in .050" increments? In that case, I could see why shimming would be necessary if the correct preload fell in between consecutive pushrod lengths.
Re: Rocker preload </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Buckshot:
<strong>That's why I asked about the pushrod length before I ordered. Aren't pushrods sold in .050" increments? In that case, I could see why shimming would be necessary if the correct preload fell in between consecutive pushrod lengths.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Exactly. Every head and cam package we sell is checked for pushrod length
on an engine core.
Mikey
<small>[ October 25, 2002, 03:59 PM: Message edited by: mikey ]</small>
<strong>That's why I asked about the pushrod length before I ordered. Aren't pushrods sold in .050" increments? In that case, I could see why shimming would be necessary if the correct preload fell in between consecutive pushrod lengths.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Exactly. Every head and cam package we sell is checked for pushrod length
on an engine core.
Mikey
<small>[ October 25, 2002, 03:59 PM: Message edited by: mikey ]</small>
Thread Starter
Staging Lane
Joined: Feb 2002
Posts: 60
Likes: 0
From: Atlanta, GA
Re: Rocker preload So with a .030" milled head and a 7.350" pushrod I should be at the correct height. Base circle on the cam is unchanged and I'm using stock lifters, stock rockers and Rev dual springs.
Trending Topics
Re: Rocker preload </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by Buckshot:
<strong>So with a .030" milled head and a 7.350" pushrod I should be at the correct height. Base circle on the cam is unchanged and I'm using stock lifters, stock rockers and Rev dual springs.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep yep <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
<strong>So with a .030" milled head and a 7.350" pushrod I should be at the correct height. Base circle on the cam is unchanged and I'm using stock lifters, stock rockers and Rev dual springs.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Yep yep <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
TECH Fanatic
Joined: Nov 2001
Posts: 1,975
Likes: 2
From: SW Florida
Re: Rocker preload mikey...
Joe Prince stated in another post that 2.0 to 2.2 turns of the rocker bolt past zero lash would equal the correct factory spec preload.
You say its 3/4 to 1.25 turns for acceptable preload.
<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Joe Prince stated in another post that 2.0 to 2.2 turns of the rocker bolt past zero lash would equal the correct factory spec preload.
You say its 3/4 to 1.25 turns for acceptable preload.
<img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
Re: Rocker preload 2.0 to 2.2 turns, 3/4 to 1.25 turns, 22ft/lbs <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
