Thanks for updating the thread. I'll have to double check my pushrod length. I bought my stuff as a kit and got everything needed for the heads/cam swap including 7.4" pushrods. Luckily they also sent a length checker. Keep updating with any changes and the results! Vids are absolutely mandatory as well.

 

Thanks for the update(s).

7.4 pushrods are definitely to short. My valvetrain was very noisy with them but at the time I didn't have anything else.

I have 7.425's in there now and I still think it's to noisy.

Mac,

How much preload did you end up with? As for the tune, it REALLY depends on how the tuner tunes it and how aggressive he/she is with it.

Even for me, after I got my truck tuned, I went out and bought HP Tuners, did a crap ton of reading and still was able to improve over the tune that was done.

 

I think I came up with around 0.060" to 0.075" of preload. My calculation was: 7.425 - (6.8"+(11 turns*0.050")) = .075".

What idle rpm do you have with your current tune?

 

Here is the truck at idle, warmed up, un-tuned.

LSR 265 cam - YouTube

 

Mac,

Mine is 625 after it's warmed up.

FWIW,

I've been chasing a noisy valvetrain since I put the cam in some time ago. At the time of the install, all I had was 7.4 PR's and it was noisy as hell.

I then went to 7.425's and those have been in for quite some time. I've pulled the covers off numerous times to check the torque of the rockers and they were all right but I still felt it was to noisey.

Yesterday, I put 7.450's in and torqued them down to 22ft-lb and let me tell you, that valvetrain is whisper quiet. All you can hear now is the injectors cycling.

Despite what the PR checker comes out to be, listen to the valvetrain. The longer pushrod doesn't change the lift on these trucks, all it changes is the preload at the lifter.

 

Madmann, glad to hear you got it to quiet down. What's your final preload on the lifters?

 

I wish I could tell you. I don't have a PR checker myself and this was strictly trial and error. (I know, I know)

I want to see some dyno numbers. lol...I'm curious.

 

Thanks. This is great info. Seems like my truck doesn't make much noise when its cold, but once its up to temp I can hear the noise when my windows are down. Sounds like the 7.450" is the trick.

Where did you buy those pushrods?

 

I got them from Summit Racing. They are Trick Flows, 5/16, .080.

 

Here is a new video from this morning,

https://www.youtube.com/watch?v=2Vhxu2QxKn0