> All of the teeth on the distributor drive gear have sheared off.
> It was a rebuilt Autozone distributor and properly pre lubed.
A few years back, a friend of mine (Steve Grossen) ruined several Comp Cams
hydraulic flat tappet cams and distributor gears on a 351W which led him to
Rockwell (B scale) test several distributor gears. A generic auto parts
cast iron gear tested at 70, the bronze-aluminum gear at 90, and the stock
Ford iron gear was 102. Note that the soft bronze-aluminum gear was harder
than the generic auto parts cast iron gear.
> I had a new CompCams solid lifter cam with broken gear teeth right in the
> box. They replaced it as a matter of customer good faith. They said it was
> not thier fault and wasn't covered in thier warranty. It had never been
> even installed. I think that there is a problem with core quality.
Steve eventually traced his trouble to a batch of cam cores with improperly
machined gears (Comp doesn't check each gear, only a statistical sampling).
Comp replaced the cams and eventually gave him one with the "NASCAR"
treatment" (filed, wire brushed on a wire wheel, and bead blasted).
> Are they're different gears?
Yes. There are iron, bronze-aluminum, steel and even some polymer gears.
In addition not all gears of a given material will test the same on
hardness.
> It dropped in fine.
No matter what gear you use, make sure the gear is in the proper location.
For the proper alignment position, see:
http://www.bacomatic.org/gallery/album24/OHOnews18of38A replacement distributor gear may or may not have a holed drilled in it.
Ford instructions caution that the hole should not be used for alignment
purposes. Position the gear to the proper location, then drill a new hole
90 degree to the old hole. Dykem the contact pattern. Pull and inspect
gear after a while. Make sure the gear is not bottoming out and binding
and that the oil pump driveshaft isn't too long. MSD recommends using a
moly lube to break-in the cam/distributor gears. They say squirting it
on the gear is insufficient and suggest using a toothbrush to work it into
the pores of the metal. Some sources recommend that whenever you remove
a distributor, that you mark it so you can reinstall the gear in the same
position to maintain the wear pattern.
> I am also glad that the cam gear is ok, but I don't like the bits in the
> oil pan idea!
All those bits went some where and unless you were using a non-bypassing
oil filter, a fair bit of them were circulated around your engine. Like
George says, you need to R&R the engine.
> That's what so sad, it's a brand new rebuild!
Make sure the cam bearings were installed properly. It's quite easy to
install the front cam bearings 180 degrees out, blocking the flow of oil
to the gear. You may also want to drill the oil galley plug with a small
hole to directly spray oil on the gear.
> Are they're gears that fit in but have a different gear pitch?
It's possible to fit a 351W gear (I'd check the part number of that Autozone
distributor to make sure it isn't a 2351W part).
Crane recommends their steel gear for all cam cores now (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.
FWIW, Keith Craft uses the Ford Motorsport or MSD equivalent steel cam gear
on all of Comps cores, steel or iron. He said they had a rash of cast iron
flat tappet gear failures that were cured with the steel gear. 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.
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.
> no ZDDP in the motor oil
The primary extreme pressure (EP) anti-scuffing additive in oil is zinc
dialkyl dithiophosphate (ZDDP). Ever tightening emissions standards have
forced the reduction of ZDDP concentration in automobile oils. In high
mileage cars that consume a lot of oil, the ZDDP additive can damage
catalytic converters and the OEM's are required to meet emissions standards
for 100K miles. Since none of the new engines use flat tappet cams, they
can get by with reduced ZDDP. Flat tappet pushrod engines, especially those
with agressive lobes and high sprng pressures, still need the ZDDP additive.
Motorcycle and diesel oil still contain reasonable concentraions of ZDDP.
The June 2006 issue of Hot Rod magazine has a good article on cam failures
and lists several oils by ZDDP concentration. Shell Rotella T and Mobil
Delvac diesel oils are good stuff and still have the SL/SJ ratings for
spark ignition engines. Conventional diesel oils are typically 15W-40.
15W is thicker than 10W and the longer molecules lubricate better. The
downside is they are not good near zero degrees F. Synthetic diesel oils
are usually 5W-40 and are fine in cold weather. Delvac 1 is a diesel
synthetic oil similar to Mobil 1. Also, diesel oils have detergents and
dispersants to keep soot in suspension. However, there was a mention in
the Hot Rod article that diesel oils will have reduced quantities of ZDDP
starting in 2007. Apparently emissions standards for diesels are being
tightened so the ZDDP has to go. When that happens, we'll likely be forced
to race oils or a ZDDP additive.
A couple of other recommendations. Install a magnetic oil pan drain plug
and consider a System One oil filter that allows you to examine the filter
element for metal (and non-metaillic) debris.
> Dan Jones has a very long treatise on the subject you may be able to find
> if you search this forum.
The part numbers below apply to 351C/351M/400 and 429/460 distributor gears.
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. MSD says its
iron distributor gears are surface-hardened a few points higher than stock
gears because most performance flat-tappet cams are ground on better quality
(harder) cores.
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). One tech I spoke with at Comp said the Ford hydraulic
roller cam gear was prefered over a standard cast iron gear. 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. Also, Keith Craft uses
the Ford steel gear on both iron flat tappet and steel roller tappet
cam cores. He said about 4 years ago, he started having cam gear wear
problems with standard flat-tappet iron cams from both Comp Cams and Lunati.
He switched to the Ford steel gears on those camshafts and has had no more
problems. He told both Comp and Lunati about it but both companies reacted
as if he were crazy. BTW, he uses the M-12390-J p/n gear on FE engines.
Apparently FE and 351C/429/460 distributors have the same outside diameter
and MSD has an FE distributor with the proper inside diameter.
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. Rob at Blue Oval
recommended this gear. Comp Cams 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
