I am thinking about upgrading my stock rocker arms to Comp cams magnum 1.6 roller tip rockers. I currently have stock heads and I am running the crane compucam 2032 now powermax cam that has .452" and .465" lift and I have the matched valve springs, crane pt.# 99848. My question is, do you think this will be alright with my stock heads that have pressed in studs and will I need a different length pushrod or are the stock pushrods ok. Or do you think I'll be better off with the 1.52 ratio or just stick with stock. I would really like to use the 1.6 ratio because my cam is lacking a little in lift. Also do you guys know of any problems with any clearance issues, such are piston - valve clearance, or the length of the slot in the rocker arms. Thanks for all you help.

 

Well, with any additional lift over stock specs, screw in studs are a good idea. I currently have a ZZ4 cam 478/510 and I'm still running the press ins with no problem, but I'm really hoping I don't run into trouble.

I've looked into this quite a bit too, and I've found that additional lift over a 1.5 or a 1.52 doesn't do much. What does help is the fact that a factory stamped rocker flexes, and the aftermarket piece doesn't. That's where MOST of the benefit is seen. That slight little extra bit of lift is more than likely not gonna give you too much.

....as for clearance, I'm also interested.

Anyone?

 

I have a 1989 5.0 Litre GTA with screw in rocker arm studs. I had the valve covers off a couple of days ago to check this very thing and to repaint the valve covers. There appears to be lots of extra room for the 1.6 ratio rocker arms. The Comp Cam I have produces about .48" of gross valve lift and with 1.6 ratio rocker arms this would be increased to about .51".

Go with the Comp Cam Pro Magnum or Crane Gold Race Extruded Roller rocker arms if you can afford another $150. The roller fulcum is more important than the roller tip. You will probably need upgraded springs and for about $20 now is the time to put in some better valve stem seals.

 

I found this article which indicates you can go as high as .60" of gross valve lift before you have a clearance problem.

https://www.thirdgen.org/newdesign/tech/mods2.shtml

 

I found this article which indicates you can go as high as .60" of gross valve lift before you have a clearance problem.

https://www.thirdgen.org/newdesign/tech/mods2.shtml

 

I ran into clearance problems with the pushrod and cyl head slot when I installed 1.6 crane stamped roller tip rockers on my 87 gta motor. I have been told different length pushrods will fix the problem. I filed my heads out close to 1/8" and retained the stock rods.