[DeTomaso] Parts for hydraulic roller camshaft

[Daniel C Jones]

There are two approaches to install a hydraulic roller cam in a 351C. The
first replicates what Ford did with the 5.0L V8.  On the 5.0L, Ford used a
stamped steel hold down bracket (a.k.a. the "spider"), individual hydraulic
roller lifters and bars (a.k.a "dog bones") that pair the lifters together
to keep the roller oriented on the camshaft.  Ford also revised the block
casting with bosses for the spider and taller lifter bores.  The cam material
was changed from iron to steel and a matching steel gear installed on the
distributor.  The spider bolts to the lifter valley to retain each pair of
lifters.  The lifter bore height was increased to match the taller roller
lifters which also required shorter pushrods.  Clevelands were not originally
equipped with roller lifters so their lifter bores are relatively short and
the block was not cast with bosses for the spider.  To use this approach in
a 351C, you'll need to drill and tap a couple of holes in the block for the
spider and a reduced base circle cam that lowers the taller roller lifters
in their bores are required.  Comp Cams hydraulic roller retrofit kits use
this approach.  Since the lifter is taller and the base circle of the cam
is changed, figure on custom length (shorter) pushrods.  It varies from
block-to-block but there may be an interference problem.  The cast-in X's
behind the lifters in the corners of the valley in 351C blocks can interfere
with the spider and may have to be ground down.  It may not end there.  A
friend ordered a custom hydraulic roller cam from Comp and tried to install
it in his iron 351C block.  The Ford 5.0L type lifters (which measure the
same as the Comp lifters) hit the dog bones in a couple of the lifter bores.
Apparently the lifter bore height varies enough in production 351C blocks to
make some of them too short for the Ford or Comp lifters.  Though Comp assured
him it would all fit, they refused to refund him the cost of the custom cam.
His fix was to try the second method.

The second approach uses paired (aftermarket) roller lifters tied together
by link bars attached directly to the lifter bodies.  This disepenses with
the spider and dog bones arrangement and any potential interference issues.
Crane was the first to make these lifters for a 351C but Comp has recently
introduced a version as well.  The Crane aftermarket link bar lifters have
the oil hole lower on the body so don't need a taller lifter bore or a
reduced base circle cam.  Cranes lifters are p/n 36532-16.  The same lifters
are also sold by Ford Motorsport under part number M-6500-S58 ("Early Block
Hydraulic Roller Lifter Set").  Edelbrock also sells a linked lifters for
SBF applications under part number 97453.  The Crane lifters are widely
recognized as the best currently on the market.  They are stronger, have
better tolerances and generally provide better RPM than the OEM Ford lifters.
A friend uses the Ford Motorsport version of the Crane lifters and has tested
them to 9000 RPM.  The downside is the lifters are over $400 a set but they
are re-usable (unlike flat tappet lifters).  Comp has introduced a similar
lifter but I've not tested those.

Rhoads also makes their variable duration lifters in hydraulic roller
form but I've never tested those.  The small block Ford part numbers are
RL-1008 (standard Rhoads) and RL-1008X for the new Vmax (higher RPM,
require adjustable valve train) versions. Note that though Rhoads offers
link bar styles for Chevy applications, the Ford offerings are not link bar.
Of the stock Ford style hydraulic lifters, the Sherman Racing modified
Ford lifters are the best for high RPM work.  One 351C racer reported he
picked up 500 RPM with the Sherman Racing lifters (power was flat to the
7200 RPM rev limiter, where it had been all done by 6800 RPM).  He also
that idle got a little rougher too.

On 5.0L the heads were revised to allow removal of the lifters without
removing the cylinder heads.  This isn't a problem on a 351C (or 351W)
due to the taller deck height.  There's also a lift limitation with the
stock Ford type lifters.

If you check the Comp catalog you'll see they list the same spring for
every one of their 351C hydraulic roller catalog grinds from the 260HR
(1200 to 4500 RPM, max lift of 0.510") to the 304HR (3000 to 6500 RPM,
0.612" lift).  You definitely want the upgrade spring (or more) for
something like the 304HR.  Crane's catalog also lists a single spring for
their range of 351C hydraulic rollers but their standard spring package
(dual with damper) is a fair bit it stiffer.

Another consideration to be aware of when ordering a hydraulic roller
cam is the cam core and lobe compatibility.  Hydraulic roller cam lobes
are shaped differently from race type solid roller profiles and require
their own cam cores.  Attempting to grind a hydraulic roller lobe on a
steel core designed originally for a solid race roller cam will break
through the surface treatment.  I ran into this problem with Comp Cams.
I worked with David Vizard to spec a custom cam for my engine. That cam
used Comp 3636 and 3637 hydraulic roller lobes. Comp's catalog retrofit
hydraulic roller grinds use an austempered ductile iron cam core but
Vizard thought I should use a stronger 8620 steel cam core with those
lobes so that's what was ordered.  I was later contacted by Comp and
informed they couldn't put those lobes on an 8620 steel core. Comp's -8
austempered ductile iron cores are used for hydraulic roller and milder
street solid roller grinds.  Their -9 cores are 8620 steel solid roller
cam cores.  Comp said grinding the desired shape on the -9 cores would
penetrate the surface treatment.  Comp also uses a reduced base circle
cam which I wasn't particularly fond of.  In the end, I cancelled the
Comp order and went with a similar grind from Crane.  Crane uses standard
base circle 8620 steel cam cores for their 351C hydraulic roller cams.
Be aware that different lifters have different diameter rollers and
there may be compatibility issues with very small base circles. Crane
says their roller lifters are fine on 1.090" diameter reduced base circle
cams.

Since roller camshafts are not tapered, a retaining plate or camshaft
button must be installed to keep the cam from walking.  FRPP has either
iron or steel retaining plates for 351C's and recommends the iron plate
for timing sets with iron gears and the steel for timing sets with
steel gears.  Check the stack height for proper timing chain alignment
once everything is installed.

In general, hydraulic roller lifters don't rev as high as flat tappets
for a given spring pressure.  The Cleveland's heavy valves and 1.73:1
rocker ratio only makes things worse.  There are several things that can
be done to extend the RPM range:

 1. Better lifters (Crane link bars)
 2. Better springs and lighter retainers (beehives with nickel size
    titanium retainers)
 3. Lighter valves (titanium or Ferrear hollow stem steel)
 4. Tailored lobes (for RPM)

As an example of what can be done, a friend of mine turns in excess of
9000 RPM with a hydraulic roller cam using all the tricks (Crane lifters,
solid roller springs, titanium valves and retainers, Anderson Ford
Motorsport "Hi Rev" lobe profile).  Granted, it's a drag race only bullet
but it shows what is possible.

Finally, there's the distributor gear and cam core material compatibility
issue.  I recently posted about this but here's a review.  There are
several distributor gears to choose from:

1. Cast Iron Distributor Gears
 These are the standard distributor gears used on hydraulic and solid flat
 tappet camshafts which use iron cores.  Not compatible with most hydraulic
 or solid roller cam steel cores.  However, Comp Cams claims there -8 part
 number hydraulic rollers (which use a cast iron core) are compatible with
 standard cast iron cam gears.  Note that some cast iron gears from auto
 parts stores are substantially softer than OEM iron gears.  Also note that
 some cam companies use a harder core for certain race solid flat tappet
 grinds which may require a bronze (or other material) gear.

 2. Ford Motorsport Steel Gear
 P/N M-12390-J (1.421" OD, 0.531" ID, for 351C) in the FRPP catalog.
 From page 105 of the 2005 FRPP catalog: "Steel gears are compatible with
 billet steel camshafts (hydraulic roller type)".  Comp Cams also claims
 the Ford gears are compatible with their -8 austempered ductile iron
 hydraulic roller cam cores (Comp also uses the -8 cores for some solid
 street roller cams).  According to MSD, the Ford mild steel distributor
 gears (as fitted to engines with factory hydraulic-roller-cams) are softer
 than the common ductile iron gears, but harder than bronze.  MSD also
 claims that Chevy uses a harder cam core for it's factory hydraulic rollers
 and uses cast iron gears but that its gears don't last as long as the Ford
 gears.  Some 5.0L Ford racers have used the Ford gear on steel cam cores
 without incident and some builders run the Ford steel gear on cast iron
 flat tappet cams as well.

 3. Crane Steel Gear
 Crane has a coated steel gear which they claim is compatible with induction
 hardened or carburized steel roller cores, as well as iron flat tappet cores.
 Their website refers to it them as "specially coated and processed steel
 distributor gears using either cast flat faced lifter or steel roller
 camshafts".  They list two part numbers for 351C distributors:

 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

 Crane does not recommend the use of their gears on camshafts that have been
 previously run with other types or materials of gears. Comp did not recommend
 this gear on their -8 cores.  Mike Trusty ran a Crane gear and had it fail in
 short order.  Asa Jay currently runs Crane's gear on a Crane steel roller cam.
 I'm told but have not verified  that Crane's earliest steel gears were made
 like the Ford gears but their new gears are different.  It may be the case
 that Mike's gear was the early version and Asa Jay's the late?  In any case,
 I've spoken with several people who are running the current Crane gears with
 no problems.  Asa Jay was kind enough to remove his distributor and check the
 gear and reported it had a normal contact pattern and wear.

 4. Mallory Distributor Gear
 Mallory makes a distributor gear for their distributors that are made
 specifically for "austempered ductile iron billets" and "proferal billet"
 cams.  It is supposed to be compatible with the Comp Cams austempered iron
 cam cores.  As I understand it, the gear is heat-treated for compatibility.

5. Bronze-Aluminum Distributor Gears
 Generally softer than iron.  Compatible with most cam cores but wears
 rapidly.  A bronze distributor gear is essentially sacrificial, wearing
 the distributor gear instead of the roller cam gear.  Usually specified
 for solid roller cams.  Note that hardness can vary from manufacturer to
 manufacturer.  If running one of these gears, you may want to run an
 oil filter without a bypass so the filter catches the wear particles.
 On a 351C, consider using Purolator oil filter number L30119.  It's a
 full size replacement for the FL-1A Ford/PH8A Fram filter.  It has no
 bypass spring in the middle but it does have the rubber flapper for
 anti-drainback.  The original application is for a 1978 Nissan 510, 2.0L
 4 cyl engine (L20B) which had the bypass valve in the engine block.
 This filter cross-references to a Fram PH2850, a Motorcraft FL-181,
 and a Wix 51452.  However, those filters have not been verified and may
 have a bypass.  It appears after 1978, Nissan went to a half height
 filter.  Purolator part number L22167 fits that application and does not
 have the bypass spring but does have the rubber flapper for anti-drainback.
 Race engines may want to run dual filters.

 6. Comp Cams Carbon Ultra-Poly Composite Distributor Gear
 Also meant as a replacement for rapid wearing bronze gears, Comp has a
 composite material gear.  These are currently only available for Windsor
 Fords and small and big block Chevys.

Dan Jones