HELP, installed heads and new cam, knocking like hell!!
#61
TECH Senior Member
iTrader: (4)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Orange Peel
I plan to change the oil before I redo the pushrods today. The heads aren't milled but I'm using a thinner gasket. The heads were deck cleaned, probably not that much taken off. Just figured I would have both sets in case one wasn't right.
#62
10 Second Club
iTrader: (5)
Join Date: Nov 2001
Location: Cali/Bay Area
Posts: 3,412
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
What is the preload with the 7.350 PR's? If you know that then you would know if you need the 7.4's or not. For comparison, I run the Comp replacement lifters as well with my Trex which is only slightly smaller lift than yours and they hold up to 7400 RPM fine so far. I also run a .027" gasket and 7.350 PR's with about .025" preload and very little noise. Glad the knock is gone but I would change the oil and let it run to full operating temp.
Dan
Dan
#63
TECH Fanatic
Thread Starter
iTrader: (20)
Join Date: May 2004
Location: Gilbert, AZ
Posts: 1,365
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Don't know the base circle of the cam, I know that the preload was only about 1/2 turn to 22ft lbs from zero lash on some. I think they are a tad short, so I will recheck the preload with the 7.4's.
#68
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by Orange Peel
Don't know the base circle of the cam, I know that the preload was only about 1/2 turn to 22ft lbs from zero lash on some. I think they are a tad short, so I will recheck the preload with the 7.4's.
#69
TECH Resident
Join Date: Sep 2003
Location: Working in the shop 24/7
Posts: 848
Likes: 0
Received 1 Like
on
1 Post
![Cool](https://ls1tech.com/forums/images/icons/icon6.gif)
So far it looks like the shorter push rods were giving the valvetrain some additional "lash" instead of preload.
Hence the very loud valvetrain. Scott's adjusting the rockers per the instructions on the FTI site right now. From what the first run through shows, the 7.400 length push rod gives him about 3/4 of a turn, from zero lash, to torque. Should take care of the loud valvetrain.
It's progressing in the right direction...
Ed
![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Ed
#70
TECH Fanatic
Thread Starter
iTrader: (20)
Join Date: May 2004
Location: Gilbert, AZ
Posts: 1,365
Likes: 0
Received 0 Likes
on
0 Posts
![](https://ls1tech.com/forums/images/ranks/ls1tech10year.png)
![Default](https://ls1tech.com/forums/images/icons/icon1.gif)
Originally Posted by EDC
So far it looks like the shorter push rods were giving the valvetrain some additional "lash" instead of preload.
Hence the very loud valvetrain. Scott's adjusting the rockers per the instructions on the FTI site right now. From what the first run through shows, the 7.400 length push rod gives him about 3/4 of a turn, from zero lash, to torque. Should take care of the loud valvetrain.
It's progressing in the right direction...
Ed
![Bang Head](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_banghead.gif)
![Happy](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_stretch.gif)
Ed
![The Jester](https://ls1tech.com/forums/images/smilies/LS1Tech/gr_jest.gif)