Hello,

I'm in the process of rebuilding a 460 and last night I installed the heads along with new lifters, new pushrods and what was going to be new rocker arms.

The pushrods are of the same length of the ones I removed. The new rockers I was going to install were CompCams 1411-16 but when I opened the box I noticed the new rockers did not have the stud needed to mount them to the post. I guess there is a conversion kit you can buy but I didn't want to mess up the pushrod length with a new rocker and adapter.

I decided to re-use my old rockers (the non-adjustable type) cause they are in good shape and I'm impatient that way.

When I installed the rockers and measured the gap in between rocker and valve stem I came across a few where the gap was a little longer than desired. I'm not sure I was measuring right as I kind of glazed over when reading the instructions to test the gap.

What I did was lightly pry in between the rocker and spring retainer until the lifter compressed and then measured the gap in the valve stem and rocker. On a few of them I had a little vertical play with the feeler gauge.

Oh and if it helps I put a new camshaft in as well. The details can be seen in this picture.





So my questions are -

1) Is it ok to use the old rockers?
2) For performance reasons is it worth upgrading to new ones?
3) Did I perform the gap test properly when measuring the valve stem and rocker distance?
4) How important is it to get the gap correctly? If needed, I guess I need to order a few longer pushrods.
5) The machine shop set me up with this cam. Can anyone tell me about it? In particular is this an upgrade over stock?


Sorry for all the questions but before I button the engine up and get it mounted I want to make sure I am taking the approach.

Thanks all!

 

You need to check lifter preload which imo should be from .020-.040. There is no gap/lash in a hydro cam rocker arm. Now that you have changed the cam and had machine work done push rod length will change. Most all aftermarket cams are ground on a different base circle which means the stock length push rods will probably not work. You need to call Summit or some other company that sells push rod length checkers, they aren't expensive. Once you determine your new length you add the preload figure to the new measurement then order new push rods of that length. Bolt your rockers down and your done. Now I should mention with a non adjustable valve train it is extremely important that the machinest that ground the valves and seats equalized all the valve tip heights. If not you will have an impossible task on your hands because you could need many different push rod lengths to make up the differences. You should always check over any head after it comes back from the machine shop to make sure they all are within imo .010"

 

Thanks Mark! I just ordered the 79011 checker from compcams.

Can you explain the lifter preload a bit?