Bugpack HD alu pushrods in WBX loosing the tip's

[fastback]

was only going to check my valve clearance on my WBX yesterday but got a surprise.
almost all pushrods had loose tip's?!
some on the factory end and some on the end i cut to length.
the setup is pretty mild with a ~9.5mm lift cam stock 1:1.1 rockers and stock wbx springs(dual's)
reving to 7K with 22psi boost.

DSC01994 (Small).JPG

[Marc]

Since I'm assuming you aren't running with your valve lash too loose, the first thing that comes to mind is that due to the combination of lift and geometry on your engine the pushrod ends are being knocked side-to-side at one extreme of the travel. Did you notice if the loose ends were all at the rockerarm end? (if some were at the lifter end, that pretty much blows this theory out of the water).
Some pushrod ends are made with a more spherical contour, like these, to handle this issue:


If this problem exists with the geometry right (set so that the pushrod is perpendicular to the rockerarm's seat at ~50% lift) you'll need to round up some "ball-end" pushrods to solve it. You didn't say if that was lift at the lobe or at the valve, but either way 9.5mm isn't a lot of lift, and 7K isn't extreme RPM, so I can't see this being a problem with stock rockerarms unless the geometry is way off...it may just mean that the fit isn't tight enough on this make of pushrod.

Personally I'm content with CrMo pushrods and setting my valvelash to near-zero, but if you want to run aluminum I've only heard good things about these ones:
http://www.aircooled.net/new-bin/viewpr ... 10&cartid=

[fastback]

hi marc
thx for your reply

i had the valve lash set to 0.10mm and the tip's came loose pretty random.
some in the lifter end ,some in the rocker end.
some in factory end and some in the end i cut and inserted the tip's
the lift is measured at cam and i set the geometry correct also..

i have used cro-mo rod's earlier but wanted to try som alu ones to keep the lash more consistent on a cold and hot angine as i never get those cro-mo ones to be good at both cold and hot engine in my WBX

maybe those sircooled net is a better quality aluminium and has a tighter fit for the tip's
IF that is my issue then

[Carsten B]

Buy once and cry once Jørn

I think the problem is the quality of the alu and the tips.

Buy the 1000 HP ones!

Carsten

[fastback]

will do for my current project

this is a "ventepølse" engine

[Rolf]

Jørn, have you measured pressure of the WBX springs?
I have measured a lot of springs lately and alot of them
was waay to soft but they where all used springs. Lots
of them had very different pressure even from the same
engine.
Could sound like valve float or ignition cut off at RPM limiter..
Fuel cut off is way better and not so hard on valve train parts.

I have no experience with Bugpack alu push rods.

Just my 2 cent:o)


/Rolf
Denmark