The older valve covers are a touch lower in height than the later ones; the baffles are a little bit different too; I have one of each; you can tell by the long profile the difference, without regard to the front being sloped as compared to vertical.
Seemed to me there was a tower difference; maybe EB mentioned it a few moons ago.
>>>*Yep, it's been many moons since we even ran into this one.
*Part of the reason is as time goes on we see less and less of the older engines. Without being 100% sure, it appears that the earlier 20R and 22R engines had a lot of "fitting" work done by the factories, so we were running into a few sets of rocker shaft stands that were actually taller than later ones. Not by much, but I have measured up to .030" difference.
That was embarrassing when we would rebuild a rocker shaft assembly and have it rock on the top of the casting. It was either that or someone beat us to them and had a setup milled to correct rocker arm angles when running reground camshafts.
The later ones seem to be much more consistant so differences like this correct themselves over time as we see less and less of those early engines.
Surfacing of course affects how high the stud sets too.
It is important to remember to not use a tap, those can remove metal. We cut a groove in the threads of an old head bolt to chase the threads, that works very well. Then we use brushes and with the block upside down we blow out the thread holes completely.
If it is going to interfere we will then cut a notch for clearence, this works fine too.
There was a concern regards oiling and cam lobe failures, the ARP stud being fatter. I read it on another board I think. But at this point I don't think that is a problem, still, something to check for....*EB
