[DeTomaso] Comp Cam's roller lifters

[Daniel C Jones]

> Does anyone have any experience with the Comp Cam's retrofit kit's such
as this?

There are two ways to run a hydraulic roller cam in a 351C.  The first is
to run link bar lifters.  The other is to run the spider and dog bones
arrangement similar to what was introduced in the mid 1980s on the 5.0L
Ford V8.  The Comp retrofit kit is the latter.  We've run both arrangements
and there are some issues to be aware of.  It varies from block-to-block
and depends upon the size of the chamfer at the top of the lifter bore but,
on many blocks, the oil feed is exposed at maximum lobe lift on stock base
circle cams.  Some manufacturers (like Comp) will reduce the base circle of
the cam so the OEM type lifters can be used.  As a rule, irregardless of
how much lift that a camshaft has, the lifters generally all stop in
approximately the same location at the top unless the base circle is
deliberately reduced which can cause problems at the other end of the
lifter bores.  With a reduced base circle cam, the OEM lifters will usually
be safe at maximum lift but some blocks will have interference problems
with the dog bones.  A local shop which uses the Comp retrofit kit has a
fixture to machine the block for clearance but it can also be done by
hand.  Comps link bar lifters have the oil feed (and associated band on the
lifter) in the same place as the OEM lifters so have the same problems at
max lobe lift.

Other retrofit link bar lifters like the Crane, Gaterman (copies of the
Crane), Howards (made by Gaterman), Lunati (made by Morel) have the oil
feed placed lower on the lifter body and do not have the max lift
problem.   My favorites are the Crane link bars but they are quite
expensive.  The Lunati/Morel hydraulic roller lifters cost about half what
the Cranes do and seem to work well.  Be aware there are some Chinese
knock-offs of the Cranes that should be avoided (tested on a spring load
machine and failed).

Comps kit comes with pushrods, springs and timing chain set.  Comp doesn't
make the timing chains and gets them from a variety of manufacturers.
Often (usually) the gears are from one manufacturer and the chains are from
another.  There are some good and some very bad chains out there so you
need to verify the name on the chain links.  Avoid chains with no name or
"Rolon".  The pushrods are shorter for the taller hydraulic roller lifters
but may not be correct for your engine.  Due to tolerance stack up in the
cam base circle diameter, rocker arm, whether or not the heads and/or block
have been milled, the pushrod length you need may be different.  Given the
angles involved with the canted valve heads, it is important to get the
pushrod length and valve train geometry correct.

Have your heads been converted to studs and guide plates or are they the
original pedestal mount?  What rocker arms are you using?  The spring loads
required for a hydraulic roller cam may exceed the pedestal mount bolt
strength.

Another issue is distributor gear compatibility.  The cam core can be made
from a variety of materials, generally either on of several steels or a
SADI core.  Unless you get a custom grind, Comp uses a SADI core.  SADI
stands for selectively austempered ductile iron.  SADI cores are generally
compatible with cast iron distributor gears.  Be aware the quality of cast
iron gears varies greatly.  Following several cast iron gear failures, a
friend Brinneltested several different cast iron distributor gears and
found that some gears (especially those purchased from auto parts stores)
were softer than the OEM Ford cast iron gear and some were even softer than
an aluminum-bronze gear.  Mallory makes a distributor gear for their
distributors that is made specifically for "austempered ductile iron
billets" and "proferal billet" cams.  "Proferal" is a grade of iron alloy
that is used primarily for non-roller camshafts because of its anti-wear
characteristics.

> I used the Crane Cams roller conversion kit, with a Crane 351C hydraulic
roller cam and lifters.

We've used the Crane kit before as well.  It differs from Comp in that
Crane uses an 8620 steel cam core of standard base circle.  The steel core
requires one of Crane's compatible steel distributor gears:

 52970-1 Ford V-8 70-82, Boss 351-351C-351M-400 for 0.500" shaft diameter
 52971-1 Ford V-8 70-82, Boss 351-351C-351M-400 for 0.531" shaft diameter

As noted above, the size of the lifter bore chamfer determines whether a
standard base circle cam like Crane uses will work in a specific block with
OEM style lifters.

We've used both steel and SADI cores successfully (with the proper
distributor gear).  The Gaterman/Howards or Morel/Lunati link bar lifters
are inexpensive enough that we no longer use the OEM style retrofit kits.
Rather than buying a kit with parts of unknown brand and specification, I
prefer to put together parts of known pedigree that fit the application.  A
custom hydraulic roller cam is around $100 more than an off-the-shelf grind
which may not match your engine.

> When Denny Aldridge built our 351C he used Comp Cams roller lifters.
Thank the lord above that he then dyno'd the engine - and found the lifters
would not stay up.

Plus one on the dyno testing.  We found a link bar that had come detached
on a Crane lifter during a dyno test.  This was back when Crane went out of
business but before they reorganized.  Someone had bought the remaining
inventory and had sold the lifters without realizing they had not been
finish machined.  The specific problem was the link bars had been pressed
into place but the ends of the axles had not been peened to retain the link
bars.

Dan Jones
-------------- next part --------------
   > Does anyone have any experience with the Comp Cam's retrofit kit's
   such as this?
   There are two ways to run a hydraulic roller cam in a 351C.A  The first
   is to run link bar lifters.A  The other is to run the spider and dog
   bones arrangement similar to what was introduced in the mid 1980s on
   the 5.0L Ford V8.A  The Comp retrofit kit is the latter.A  We've run
   both arrangements and there are some issues to be aware of.A  It varies
   from block-to-block and depends upon the size of the chamfer at the top
   of the lifter bore but, on many blocks, the oil feed is exposed at
   maximum lobe lift on stock base circle cams.A  Some manufacturers (like
   Comp) will reduce the base circle of the cam so the OEM type lifters
   can be used.A  As a rule, irregardless of how much lift that a camshaft
   has, the lifters generally all stop in approximately the same location
   at the top unless the base circle is deliberately reduced which can
   cause problems at the other end of the lifter bores.A  With a reduced
   base circle cam, the OEM lifters will usually be safe at maximum lift
   but some blocks will have interference problems with the dog bones.A  A
   local shop which uses the Comp retrofit kit has a fixture to machine
   the block for clearance but it can also be done by hand.A  Comps link
   bar lifters have the oil feed (and associated band on the lifter) in
   the same place as the OEM lifters so have the same problems at max lobe
   lift.
   Other retrofit link bar lifters like the Crane, Gaterman (copies of the
   Crane), Howards (made by Gaterman), Lunati (made by Morel) have the oil
   feed placed lower on the lifter body and do not have the max lift
   problem.A A  My favorites are the Crane link bars but they are quite
   expensive.A  The Lunati/Morel hydraulic roller lifters cost about half
   what the Cranes do and seem to work well.A  Be aware there are some
   Chinese knock-offs of the Cranes that should be avoided (tested on a
   spring load machine and failed).
   Comps kit comes with pushrods, springs and timing chain set.A  Comp
   doesn't make the timing chains and gets them from a variety of
   manufacturers.A  Often (usually) the gears are from one manufacturer
   and the chains are from another.A  There are some good and some very
   bad chains out there so you need to verify the name on the chain
   links.A  Avoid chains with no name or "Rolon".A  The pushrods are
   shorter for the taller hydraulic roller lifters but may not be correct
   for your engine.A  Due to tolerance stack up in the cam base circle
   diameter, rocker arm, whether or not the heads and/or block have been
   milled, the pushrod length you need may be different.A  Given the
   angles involved with the canted valve heads, it is important to get the
   pushrod length and valve train geometry correct.
   Have your heads been converted to studs and guide plates or are they
   the original pedestal mount?A  What rocker arms are you using?A  The
   spring loads required for a hydraulic roller cam may exceed the
   pedestal mount bolt strength.
   Another issue is distributor gear compatibility.A  The cam core can be
   made from a variety of materials, generally either on of several steels
   or a SADI core.A  Unless you get a custom grind, Comp uses a SADI
   core.A  SADI stands for selectively austempered ductile iron.A  SADI
   cores are generally compatible with cast iron distributor gears.A  Be
   aware the quality of cast iron gears varies greatly.A  Following
   several cast iron gear failures, a friend Brinneltested several
   different cast iron distributor gears and found that some gears
   (especially those purchased from auto parts stores) were softer than
   the OEM Ford cast iron gear and some were even softer than an
   aluminum-bronze gear.A  Mallory makes a distributor gear for their
   distributors that is made specifically for "austempered ductile iron
   billets" and "proferal billet" cams.A  "Proferal" is a grade of iron
   alloy that is used primarily for non-roller camshafts because of its
   anti-wear characteristics.
   > I used the Crane Cams roller conversion kit, with a Crane 351C
   hydraulic roller cam and lifters.
   We've used the Crane kit before as well.A  It differs from Comp in that
   Crane uses an 8620 steel cam core of standard base circle.A  The steel
   core requires one of Crane's compatible steel distributor gears:
   A 52970-1 Ford V-8 70-82, Boss 351-351C-351M-400 for 0.500" shaft
   diameter
   A 52971-1 Ford V-8 70-82, Boss 351-351C-351M-400 for 0.531" shaft
   diameter
   As noted above, the size of the lifter bore chamfer determines whether
   a standard base circle cam like Crane uses will work in a specific
   block with OEM style lifters.
   We've used both steel and SADI cores successfully (with the proper
   distributor gear).A  The Gaterman/Howards or Morel/Lunati link bar
   lifters are inexpensive enough that we no longer use the OEM style
   retrofit kits.A  Rather than buying a kit with parts of unknown brand
   and specification, I prefer to put together parts of known pedigree
   that fit the application.A  A custom hydraulic roller cam is around
   $100 more than an off-the-shelf grind which may not match your engine.
   > When Denny Aldridge built our 351C he used Comp Cams roller lifters.
   Thank the lord above that he then dyno'd the engine - and found the
   lifters would not stay up.
   Plus one on the dyno testing.A  We found a link bar that had come
   detached on a Crane lifter during a dyno test.A  This was back when
   Crane went out of business but before they reorganized.A  Someone had
   bought the remaining inventory and had sold the lifters without
   realizing they had not been finish machined.A  The specific problem was
   the link bars had been pressed into place but the ends of the axles had
   not been peened to retain the link bars.
   Dan Jones