Kai---Fair enough. If these weep holes were drilled and polished so as
to not be abrasive to the cam lobes, then I like the idea of lubrication
directly to the lobes.
I was not able to click on to enlarge the lifters as shown in the PRI
site. It still begs the question of why the hole drilling of solid
lifters isn't more of a practice with other engine designers. Or is it?
Dick
Dick Taylor), 6pack@autox.team.net Subject: Re: Lifter Mods
Drilling a hole at the bottom of the lifter would be similar to a
large pit. Pits are said to cause a more rapid decline of the lobes.
This might be the reason that this "extra" oiling has never
been practiced.
Kai wrote:
Dick
I disagree. As Darrell Ramsey pointed out, PRI offers the weep hole in
their TR6/GT6/Spit lifters. Crower also offers to drill weep holes in
their lifters as an option when you order. And I consider Crower's
engine products to be some of the finest in the aftermarket, although
they really do not do much British stuff.
A pit is a breakdown of the metal at the surface of the lifter, where it
was inevitably softened over time. Whereas a purpose drilled oiling hole
would be chamfered and micropolished so as to have no negative effect on
the cam lobe it rides on. Additionally, the material surrounding the oil
hole should be of the same hardness, especially if it was re-hardened
after the drilling process... which it should be, as you will be
piercing the hardened surface to make the penetration.
These lifter oil holes are REAL small. Crower's hole is .024" in
diameter... and looks more like it was created by a precision needle
than a drill bit.
The oil holes are just not common place in the British realm of engine
building.
Kai
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