Generation III Internal Engine 1997-2006 LS1 | LS6
Sponsored by:
Sponsored by:

Think I found the problem

Thread Tools
 
Search this Thread
 
Old 12-23-2003 | 07:58 PM
  #1  
work in progress's Avatar
Thread Starter
11 Second Club
iTrader: (2)
 
Joined: Feb 2002
Posts: 918
Likes: 1
From: Texas
Default Think I found the problem

After installing my heads and cam I had no power increase over stock. I was asking around about what pushrod length to use, and was told the stock length would work as long as I was within 1 to 1.5 turns from 0 lash. Well that is wrong, they are supposed to by 22 ft lb. I guess the guy thought I had adjustable rockers. The rockers are basically tightened all the way down and maybe holding the valves open. Will this cause a valve to burn? What can of damage would be possible if any?
Old 12-23-2003 | 09:03 PM
  #2  
JoeyGC5's Avatar
TECH Addict
iTrader: (24)
 
Joined: Jun 2003
Posts: 2,645
Likes: 0
From: St Joe, MO
Default

Worst case possible cam lobe harm, lifter collapse, or piston to valve contact. IMO
Old 12-23-2003 | 09:09 PM
  #3  
CAT3's Avatar
Restricted User
iTrader: (9)
 
Joined: Sep 2002
Posts: 7,603
Likes: 0
From: Sierra Vista, AZ
Default

Well, actually the lifter preload isnt too far off, but it is off. Yes you should have torwued them down to 22ftlbs, and in doing so, whould have turned the bolt about 1-1 1/2 turns. Most important part being the torque. Back them off, hand tighten with a qtr inch ratchet, and once bottomed, torque.
Old 12-23-2003 | 09:54 PM
  #4  
work in progress's Avatar
Thread Starter
11 Second Club
iTrader: (2)
 
Joined: Feb 2002
Posts: 918
Likes: 1
From: Texas
Default

Originally Posted by CAT3
Well, actually the lifter preload isnt too far off, but it is off. Yes you should have torwued them down to 22ftlbs, and in doing so, whould have turned the bolt about 1-1 1/2 turns. Most important part being the torque. Back them off, hand tighten with a qtr inch ratchet, and once bottomed, torque.
SO do you think I would be down on power the way they are, or is this something that I will fix with marginal results?
Old 12-23-2003 | 10:11 PM
  #5  
CAT3's Avatar
Restricted User
iTrader: (9)
 
Joined: Sep 2002
Posts: 7,603
Likes: 0
From: Sierra Vista, AZ
Default

If the valves are not fully closing AND opening, yes you could be down on power, but I would imagine that youd also hear it, either a ticking, rushing air, or popping. But maybe not. Redo them, takes an hour.
Old 12-23-2003 | 10:15 PM
  #6  
work in progress's Avatar
Thread Starter
11 Second Club
iTrader: (2)
 
Joined: Feb 2002
Posts: 918
Likes: 1
From: Texas
Default

I m going to do them for sure, I do have some valve train noise that i didnt have before. I was told with the cam that I would get more noise. Either way they will be torqued to specs, and if there is no change I will keep searching! thanks for your in put!
Old 12-23-2003 | 10:39 PM
  #7  
Slowhawk's Avatar
LS1Tech Sponsor
iTrader: (12)
 
Joined: Nov 2001
Posts: 14,865
Likes: 6
From: Bridgewater,Ma
Default

Originally Posted by work in progress
After installing my heads and cam I had no power increase over stock. I was asking around about what pushrod length to use, and was told the stock length would work as long as I was within 1 to 1.5 turns from 0 lash. Well that is wrong, they are supposed to by 22 ft lb. I guess the guy thought I had adjustable rockers. The rockers are basically tightened all the way down and maybe holding the valves open. Will this cause a valve to burn? What can of damage would be possible if any?
If they are only tightened 1 - 1 1/2 turns and not torque'd,then the rockers would of already fallen off.
The rocker's need to be torque'd the 22 ft/lbs to keep them from loosening,ie-falling out.So I'm sure your mechanic did it right.
I think this is what you mean-- You could possibly have too much preload causing the valves to hang open.On most H/C cars I do I install 7.350 pushrods because the Heads are shaved .030..I find the preload is arounf 1/2 -3/4 turn's=.080 preload.

So you need to find out how much preload you have,then go from there.

Trending Topics

Old 12-24-2003 | 10:46 AM
  #8  
work in progress's Avatar
Thread Starter
11 Second Club
iTrader: (2)
 
Joined: Feb 2002
Posts: 918
Likes: 1
From: Texas
Default

well that wasnt the problem
Old 12-24-2003 | 11:53 AM
  #9  
P Mack's Avatar
TECH Addict
iTrader: (6)
 
Joined: Jan 2003
Posts: 2,382
Likes: 2
From: Phoenix
Default

Originally Posted by work in progress
The rockers are basically tightened all the way down and maybe holding the valves open. Will this cause a valve to burn? What can of damage would be possible if any?
Yes, you could burn a valve if the valves are being held open from too much preload. If you're worried, just do a compression or leakdown test, after you fix the preload of course.




All times are GMT -5. The time now is 05:28 PM.