turbo SBC's... was RE: Thanks for the EFI! (off topic)

[Mark S. Riley]

They were legal. Rollers never have been in the "CUP" series. Problem with
mushroom lifter camshafts are that they don't last very long. If you put an
aggressive grind that will need valve spring to maintain control, then
lifter and lobe life is very much shortened over "Normal" flat tappet cam
grinds. Also the bottom of the block "must" be spotfaced to prevent one
point of the lifter touching a casting tit or bump which breaks the foot off
the lifter. Perhaps lifter float cause you were trying to run the lightest
springs to cut down on drag and wear. Then the driver does something bright
like turn it 9600 on a restart. Also they have to be shimmed front to rear
against cam walk cause the opposite lobe will lift the wrong valve with very
little aft to fore movement. Used to see pallets of Crane, Competion Cams,
Cam Dynamics, Reed, and Crower Cams mushrooms at some of the local "CUP"
shops. They couldn't run a cam and lifter but once. Wouldn't make two races.
I use to buy the used cams and lifters and  run them in short track engines.
Valve action with a mushroom can be more radical than a roller ever dreamed
about. They just don't last long because of the loading. Oh, the lobes are
thinner to help with the "crosslift problem" because of the big foot. The
"CUP" stuff was cut for a 1" foot lifter. When Nascar outlawed the mushroom,
they all went to the ford lifter size, .850" I think. Precisioneering in
Asheville, NC does most of the lifter boring and registering for the teams.
They have a factory type lifter boring machine.
Duh, that's probably more than anyone would want to know about that "old"
stuff. later, Mark

----- Original Message -----
From: "Shannen Durphey" <shannen at grolen.com>
To: <diy_efi at diy-efi.org>
Sent: Tuesday, December 15, 1998 10:44 PM
Subject: Re: turbo SBC's... was RE: Thanks for the EFI! (off topic)


> Greg Hermann wrote:
>
> > Don't know if they are still doing it for a "cheat", but I know some
NASCAR
> > guys were running mushrooms for a while. Rollers were against the rules,
> > and the tech check was to stick something down the pushrod hole to see
if
> > the lifters would rotate. Mushrooms rotate ! :-)
> >
> Last engine I saw had Ferd lifters.  It's been a few years.
>
> Mebbe them lifters is like the gauges, they is either open or close and
nothing
> in between. ; )
> Shannen
>
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