kilby94

Last night i was helping a buddy install his new valve train setup, and we came across a confusing problem.. We were changing his setup from shaft mount roller rockers to stud mount on a set of Pro Comp Cylinder heads.. Reason for changing was because he had the Pro-comp shaft mounted rockers and they were literally coming to pieces inside the motor.. So he ordered a set of Comp guide plates and Comp stud mount roller rockers.. Well we installed the studs and guide plates, but just placing the rocker on the stud i noticed it was out of line.. It appears to me that the Studs are not sitting vertical in relation to the head.. With everything bolted up and the proper valve lash measured the roller rockers are not straight.. Its almost like the studs are in the head crooked? The rockers on the passenger side are arranged like this(but not quite this bad) // \\ // \\ // \\ // \\.... I have heard that some guide plates need to be trimmed for proper push rod angle, but that sounds a little fishy? Is it possible that these "Pro-Comp Heads" have the holes for the studs drilled and tapped at a slight angle??



Are these heads junk? Is there any way to fix this?

P.S. And I'm not much of an artist so don't criticize the drawing!!

Slo5oh

The studs should be perfectly paralell. Sounds like you need new studs unless this is some wierd mounting I haven't heard of before which is entirely possable.

Nice artwork

Portmaster

The Pro Comp is not a very high quality peice but I've never seen one as bad as you seem to describe it. Remove the rockers and loosen the guideplates to where they move around with very little effort (but some slight resistance) and then put the pushrods in and then set the rocker arms on and run the poly lock down just enought to put some light pressure on the valve stem tip. Then move the guideplate until the pushrods and rockers line up with the valves then slide the rockers off and tighten up the studs just good and snug. Then put the rockers on again and if they are still in line torque them down and move to the next cylinder.

There have been many times I've had to split a valve guide plate and weld it back together. This was such a problem on Big Block Chevys the Crane sold a guide plate already split.

Now as far as the studs being in crooked what you need to do is just set the rocker down on the stud and make sure the roller tip of the rocker touches the valve tip all the way across the roller tip. If that stud is in crooked you will see a gap under one side or the other of the roller tip. If thats the case the only thing that can fix that would be to remove the heads weld up the stud holes, machine the stud pedestals and redrill them. That gets really expensive. It would cost more to do that than probably what he paid for the heads.

If the studs are off this could have been what damaged his original rockers. Which Pro Comps does he have?

kilby94

They are the Pro-Comp 190cc i believe.. I don't really know that much about them.. He had the Pro-comp shaft mounted rockers with 1.5 intake & 1.6 Exhaust rockers.. And the first time down the track 3 of the locking allen head bolts broke off causing rockers to loosen up and needle bearings to distribute all throughout his engine.. Now he went back with all comp stuff.. Are the studs in the heads supposed to be perfectly vertical in relation to the valve? Cause there not.... And just turning the engine over by hand the locking nut is rubbing the inside of the rocker arm bad because the stud isn't straight.. And now we noticed that the rocker arm is also hitting the spring retainer when valve is closed.. What else can go wrong...

And the studs, guide plates, and rocker arms are brand new comp parts...

Portmaster

Because the rocker arm should fit pretty tight on the stud I have to wonder if he has 7/16 rockers on a 3/8 stud. Please post a picture. I've never seen one that bad. Sounds like the stud pedestals were drilled by hand. I wonder if he bought (or the previous owner) bought pedestal mount heads and tried to drill and tap the stud holes by hand. That just doesn't sound right even for Pro Comp

kilby94

I'll get some pics when i am over there tonight or tomorrow.. He got the heads new and they are for stud mount rockers.. He did have them at a cylinder head shop when they setup his shaft rockers.. I wonder if they would have done any kind of machining to fit the shaft mounts?

By the way thanks Portmaster you have been very informative to me!!