Shimming rockers?

[jaymac]

I've asked this before, but I'm trying to get a solid answer. I have GT40P's that are getting milled .030, and will be using the stock rods and rockers. How do I know if I need to shim them, and then where do I get shims and what size, how do I know how many to use, etc. I know absolutely NOTHING about shims, setting rockers, etc.
I hope to be having people who DO know helping me, but I'd like to know anyway.
Thanks,
Jeremy

 

[TC93]

What ever rockers you are setting, be sure the valves are closed. Bolt the rocker down to zero lash. To do that tighten the bolt down until the pushrod stops moving up & down and has a slight drag when spinning. Once you get zero lash, torque the bolt to specs.( want to say 15-20ftlbs) It should tighten to specs with in 1/4 to 1 full turn of the bolt. If it goes more than a full turn then that rocker will need a shim. Repeat for remaing rockers.

The shim will go between the rocker base and the U channels it sits in.....

You can get a shim kit form Summit or a locall speed shop. Crane and FMS makes them. They come in a kit with different thickness, and start with the thinnest 1st and go to next thickness if needed. There are only 2 or 3 thicknesses, I can't remembr exactly, been a while since I had bolt down rockers.

 

[jaymac]

Mike - thanks very much for your detailed response!

 

[xherdlr]

What ever rockers you are setting, be sure the valves are closed. Bolt the rocker down to zero lash. To do that tighten the bolt down until the pushrod stops moving up & down and has a slight drag when spinning. Once you get zero lash, torque the bolt to specs.( want to say 15-20ftlbs) It should tighten to specs with in 1/4 to 1 full turn of the bolt. If it goes more than a full turn then that rocker will need a shim. Repeat for remaing rockers.

The shim will go between the rocker base and the U channels it sits in.....

You can get a shim kit form Summit or a locall speed shop. Crane and FMS makes them. They come in a kit with different thickness, and start with the thinnest 1st and go to next thickness if needed. There are only 2 or 3 thicknesses, I can't remembr exactly, been a while since I had bolt down rockers.

What do you mean by "tightening to spec?" I followed a simular pattern...got zero lash and continued turning until valve almost closed. Then tighted 3/4 turn... My rockers are still a little loose. Are they OK or do I need to add Shimms? The sequence I used is what someone sent to me from Ed Curtis....

Kelly

 

[TC93]

What do you mean by "tightening to spec?" I followed a simular pattern...got zero lash and continued turning until valve almost closed. Then tighted 3/4 turn... My rockers are still a little loose. Are they OK or do I need to add Shimms? The sequence I used is what someone sent to me from Ed Curtis....

Kelly

The bolt to torque specs.... The valve should have been close before you tighten the bolt.

 

[jaymac]

I'm trying to find shims but still can't find them at Summit.
Any specific places I should look?

 

[jwzg]

Call Crane Cams and they will send you a set for a fairly low price. I think that the thin shims are 1/2 turn and the thick shims are one turn. BTW, check your pushrod length using an adjustable checker. You may have to have new pushrods, and you can get those from Crane within 48 hours.

Xherdlr, you need to follow the instructions in the above post by Myke86GT. The torque specs are 18-20 ft-lbs. Mine clattered like mad on startup and then settled into a very nice "sewing machine" whirr. Drove 300 miles yesterday and not an untoward sound to be heard.