Thanks for the heads up gearhead/jimfred . . . I will watch the pushrod hole clearances closely when I do my build. Perhaps I may even try fit & run them on the stock setup before I tear it down.

As for the instructions, they pretty much say "slap em in, set the lash and go"


barkerinstructions.jpg

Up until I read jimfred's reply on this thread I had never heard of clearance or bending problems with higher than stock ratio rockers. But I am new to wrenching on Sixes.

When I was younger we played with V8s and this was just another variable. In fact I have read several tech articles that suggest that a balance of increased rocker ratio and lobe lift is easier on the valve train than increasing only lobe lift: http://www.pontiacstreetperformance.com/psp/RockerArms.html

The other thing that I am curious about is just how tight are the pushrod holes in an inliner? Based on my measurements these rockers don't move the top of push rod very far at all.

The distance from the fulcrum to the valve stem is roughly 2.1". The stock rocker ratio is 1.5. So the distance from the fulcrum to push rod is roughly 1.4".

Well I measured the Barker's this morning:


rockerratio1.jpg

Of course Barker can't vary the distance to valve stem -- so it is roughly stock. But the distance to the push rod is indeed shorter as we would expect in order to acheive the higher ratio


rockerratio2.jpg

2.1" divided by a rocker ratio of 1.7 = 1.235". Which is a difference of .16" and with a rougly 11" push rod we are moving it about .88 degrees off perpendicular. Doesn't seem like enough to create a risk of bending the rod. Yet now that I think about it .16 is the better part of three pennies . . . perhaps I will need to do some grinding.

For those who have never seen these before, there are some more pics below . . .

stock49


barker1.jpg


barker2.jpg


barker2.jpg


[Linked Image from 49fastback.com]