[DeTomaso] Fw: Re: Pantera fall down go boo m :<(

[JDeRyke at aol.com]

In a message dated 6/28/11 11:33:00 AM, kenn_green at yahoo.com writes:

> I talked to their tech guys and they claim bigger roller bearings make a 
> big difference, so they recommend larger diameter lifters to make room for 
> the bigger bearings.  And all of them are force fed oil, which seems to be 
> become more common.
> 
Yup. IMHO, big lifters that use bigger roller wheels requires boring the 16 
lifter holes in a block oversize & bushing them, so its sort of expensive 
and is mosly for SBCs that use the smallest diameter lifters at 0.825" and do 
have problems. Fords are 0.875" and the next choice is Chrysler lifters at 
0.902". Oversized lifters also change the set-up and running characteristics 
of whatever cam they are applied to. 
There seem to be three or more failure modes for roller lifters: the actual 
roller wheel spalls from old age and low speed skidding, or cracks from 
valve-float impacts on the cam, the roller bearings and/or axle fail from lack 
of oil or old age, plus the rollers and axle flat-spot from impacts (valve 
float) that haven't yet cracked the wheel, or from running heavy valve 
springs that overload everything. So pressure lubrication of the axle & roller 
bearings is only part of the solution. Jon Kaase says the life of his solid 
roller lifters went up markedly when he went from 1/2" dia. pushrods to 9/16", 
which in his words, 'let us finally get the whole valve train under 
control'. Stock pushrods for the 351-C are four sizes smaller than that at 5/16".... 

'Course, most of this is race engineering or short-term drag stuff that 
doesn't really belong on the street. When I finally choose a cam for my street 
Fontana build, I'd like it to be a hydraulic roller for the slightly higher 
efficiency and ability to compensate for aluminum expansion with heat, not 
for more power. So I am leaning toward the Isky EZ roll bushing-type 'roller' 
lifter, with beehive springs. And at least 7/16" pushrods. FWIW- J DeRyke