Distributor gear destroyd, Help!!

[westcott cobra]

Hello all,

during a test run on the freeway yesterday, my 351C stopped working apruptly.

After a short system check I found a badly worn distributor gear, teeth thin as knifes and 30% of them gone completely.

The engine was completely rebuild with all new parts.

Distributor is(was) Mallory dual point.

Cam is:

Crane Camshaft Specification Card
Part Number: 524421
Grind Number: H-288-2 (REPLACES CCH-288-2)
LIFT: INTAKE @CAM 305 @VALVE 528 ROCKER ARM RATIO
EXHAUST @CAM 3101 @VALVE 536 1.73
ALL LIFTS ARE BASED ON ZERO LASH AND THEORETICAL ROCKER ARM RATIOS

CAM TIMING OPENS CLOSES ADV DURATION
@ .004 INTAKE 33 BTDC 75 ABDC 288 °
TAPPET LIFT EXHAUST 75 BBDC 37 ATDC 292 °

CAM TIMING OPENS CLOSES MAX LIFT DURATION
@ .050 INTAKE 8 BTDC 38 ABDC 105 °ATDC 226 °
TAPPET LIFT EXHAUST 50 BBDC 0 ATDC 115 °BTDC 230 °

Rest:
Block: 351 CJ, 4Bolt main bearings
Crank: Steel, Test Mark 4MA. Grinded, polished, nitrided
Rods: Eagle H-Beam, forged
Pistons: Speedpro, forged, coated sides, floating bolts
Heads: 2V with open chamber, reworked, volumes equalized, spring hight adjusted to max 0.1mm difference.
Springs: Comp Cams Double Springs
Pusrods: Manley Moly Rods
Rocker Arms: Scorpion Aluminium Roller
Valves: Manley
Bolts internal: All ARP, Comp Series, rods for the heads and mains
Bolts external: All ARP, Comp Series, Stainless 12Point
Intake: Edelbrock
Valve Covers: Shelby Script und LOGO
Carb: Holley 4V, 850
Oilpan: 351 CJ, production w. buffles and welded windage tray
Oilpump: Melling HV, HD modified to be adjustable
Oilpump drive shaft: ARP
Distributor: Orig. Mallory Dual point
Sparkplug wires: Taylor Blue, 8mm, Silicon Plugs, Angled
Waterpump: Edelbrock HV, Alu
Starter: Orig. Ford High Torque


Has anybody an idea what happend???

Sitting on the freeway/autobahn I replaced my died Mallory by an stock ford 351c distributor which followed the mallory in the same way 4o miles later.

This never happend to me driving american v8s the last 15 Years.

Heeeeelp!!!!!!





Cheers from Germany,

Uwe

[sllib]

Uwe;
That is usually caused by running a steel roller cam with a iron dist. gear. Suggest you replace your dist. gear with either a bronze, steel, or polymer(Comp Cams) gear.
Bill Stradtner

[Tom Wells]

Yo Uwe,

Sorry to hear of your problem - my sincerest condolences

Been there, done that:

Threads on distributor gear problems

I ended up with a Crane steel cam using hydraulic roller tappets, and a Crane steel distributor gear carefully located on the shaft to the 4.000" spec. After 9,000+ miles no visible wear when I pull the distributor.

Bottom line: you must use compatible cam & gear materials. Steel/steel or cast/cast.

You can also use a bronze distributor gear but it then becomes a maintenance item with a life of 5,000 miles or so. OK for drag racing but not for street miles.

Carefully assemble the drive gear onto the distributor shaft maintaining the four inch distance

Alas, I fear you may have destroyed the cam, as I did, necessitating its replacement as well I conclude this after seeing that you found the second distributor gear worn out suddenly as well.

I feel your pain: Ford reimbursed nothing (zero zip nada) even though they installed my gear wrong - I'm out the $2800 parts & labor to correct their mistake.

I hope my diagnosis is incorrect!

Let us know,

Tom

[Hotfingrs]

Wrong gears is the answer, but you'll also have to pull the engine and have everything hot tanked to get rid of the metal shavings and new bearings put in

[Scott S]

This is most likely your problem,

Oilpump: Melling HV, HD modified to be adjustable

HV oil pumps on a small block Ford are really hard on distributor gears, on new engines they are even worse.

Scott S

[westcott cobra]

Dear all,
thanks for the kind answers. I posted the same in "all cobra talk" and left there the following in additional:


"PS: I forgot one point maybe the most important: Pressure at oil pump is set to 114 PSI. We did the same thing with Buick and Chevy engines and nothing happend.
Is the distributor gear for Ford from such a weak material that it can not withstand the higher load comming from my oilpump?
Are there better distributor gears for high performance use available?
My one was made from steel.
Cheers from Germany,
Uwe

Wilf,
the cam is a crane hydraulik part nr. 524421.
No roller.
I'm using 5W40 Oil, shouldn't be a problem.
I will partly disassemble the engine, clean the sump, check the cam gear and oil pump.
The pressure will be readjusted to 80-85 PSI cold and 70-75 PSI warm.
The only thing I'm looking for is a better Distributor gear. Made from Steel instead of Iron??? There are steel gears availlable from Crane for my distributor.
Mine was Iron, not Steel as I posted before.
O.K. so far???
What Crane says about my cam is:
FAIR IDLE, MODERATE PERFORMANCE USAGE, GOOD MID-RANGE HP, BRACKET RACING, AUTO TRANS W/2500+ CONVERTER, 3200-3600 CRUISE RPM, 9.5 TO 11.0 COMPRESSION RATIO ADVISED. BASIC RPM 2500-5500
Thanks for helping an completely frustrated(at the moment) Cleveland driver.
Cheers,
Uwe

Rick and Perry Henry,

we pushed the pressure up because our engines are made to go 7000 revs and more. We tried to be on the "safe side".
No problem so far with chevys and buicks.
Because of the cleveland oiling problems we decided to go the same way, but we learned.................
I'm going to heed your statements, the pressure will be droped to 70-75 warm.
Sorry for my bad english writing
Thanks all,
Uwe"

Sorry for my late response, I was a little bit frustrated yesterday and tried to get as much as possible answers.


A well motivated,

Uwe

[wilf leek]

Uwe - with that cam, a steel gear should be OK, but check with the cam and the distributor manufacturer helplines.

I still think that the high oil pressure you set is the root of the problem. It multiplies the torque that the gear must transmit.

Be happy - you are the first Cleveland owner here that I know of with this problem! You are therefore unique. Have you tried the Cleveland engine forum at http://www.network54.com/Hide/Forum/119419?it=0

( don't get me wrong - I am very sympathetic to how you must be feeling right now, but it IS part and parcel of Cobra ownership).

[Tom Wells]

Yo Uwe,

You said

the cam is a crane hydraulik part nr. 524421.

also

Mine was Iron

in reference to the distributor gear.

I couldn't find the cam material on the Crane site. I ASSUME the hydraulic flat tappet cam is cast iron and therefore it sounds as if you have the correct distributor gear material. You'd need to check with Crane directly to confirm the materials.

Unfortunately this points to other causes such as the high output oil pump or the positon of the gear on the distributor shaft (or both!) as possible culprits.

Let us know how you proceed.

Tom

[Cobra 29]

I have a FMS 351W crate engine (M-6007-A351). It is rated at 385HP. The cam is a hydraulic (M-6250-A351) with roller rocker arms. I do not believe the cam is a “roller cam”.

I replaced the Duraspark distributor with a 8478 small diameter MSD distributor about a year ago but have not driven too many miles. I did not pay any attention to type of metal used for the cam distributor gear or on the new distributor. Does anyone know what type of metal (iron, hardened iron, etc.) the cam distributor gear on the cam is? What type of metal is the standard gear on the 8478 MSD?

I really do not understand the compatibility of these two metal gears. I believe I am hearing from the forums that an iron or hardened iron “roller” cam needs to be mated to a steel gear on the distributor. Does this recommendation change if your cam is not a “roller”?

[Tom Wells]

Hi Cobra 29,

I agree I wasn't totally clear about this, so here goes again

Roller cams are almost always steel cams, either solid or hydraulic roller lifters are used.

Flat tappet cams (either solid or hydraulic flat tappet cams) are non-roller lifter cams made of cast iron.

For the distributor gear, use a steel gear with a steel cam, a cast iron gear with a cast iron cam.

A bronze gear may be used with either cam (it's made of softer metal than either of these) but must be checked every few thousand miles for wear, as it will not last anywhere near as long as the steel or iron gears.

Hope this clears that up

The cam mfr can tell you what material your cam is made of and most can sell you the appropriate material gear for the distributor.

Tom

[djseed]

I am using the Crane steel hydraulic roller cam and the Crane steel distributor gear. Someone posted and said they were developed for the Busch series engines. Works great and no "bronze" problems.

http://www.cranecams.com/index.php?s...&lvl=3&prt=113

The Butcher of Cobra Lads fame documented his problems with the distributor gear installation and offered some good tips.

http://www.cobralads.com/butcher62.html

[stangman393]

Distributor gear applications are:

hydraulic roller cam - steel
solid roller - bronze or polymer
flat tappet(hydraulic or solid) - cast iron



First of all check the bottom of the distributor gear and see if you have any wear. There is a deck surface with a guide hole in it inside the block. You can see it using a flashlight with the distributor removed. I have seen a few distributors with the gear installed to low on the distridutor shaft. This results in binding the distributor gear against this deck surface when you tighten down the distributor hold down. End result is chewed up distributor gear and in worst case the cam gear will be worn. If you put in a new distributor gear with a worn cam gear it will just cause spark scatter and also the gear will wear out faster the next time. Make sure you change the oil also. Good luck.

Jeff

[westcott cobra]

O.K. so far....short update:


Engine is pulled and all bearings are checked!!

Everything O.K. so far...... the block will be cleaned afterwards.


We are going to replace the cam and set up the oil pump to 75 PSI cold.


Cheers,

Uwe

[brainsboy]

Alot of your problem was probably the 114psi. Rule of thumb is 10psi for every 1000 rpm. Unless you have stroked your motor beyond belief or turning it 11,000rpms you shouldnt need that much psi. If your motor is fairly new and your not using a remote filter or cooler a standard pump at 70psi will be more then you need. A high volume pump is probably not needed in your case, its just creating heat and robbing horsepower.

check this site out

http://www.melling.com/support/bulletins/view.asp?id=12

[westcott cobra]

Forgot one thing:

Oil cooler is installed of course.


Cheers,


Uwe

[rdorman]

Sorry to hear about your troubles! I am going to go home and pull my mallory and check it.

We basically have the same engine and I have concidered running the cam that you have. How do you like the cam? Have you had it dyno'd? What are the valve releifs in the pistons and what kind of valve clearence did you end up with? Is it installed straight up or.............?

Thanks
Rick

Oh, by the way, a good hardened steel pin should be used and adding a second never hurt a thing.

[westcott cobra]

Rick,

I like the cam because of its low cruising rpm, idle is a bit rough, but i like it that way.

The 2V and 4V open chamber heads have been the only heads available here in Germany. Therefore i choosed to install the 2Vs because of their better bottem end torque.

Engine is very quick from 2000 up to 6000 rpm. Nice.

To increase the low compression comming with a stock open chamber set up we decided to install the speedpro pistons with valve reliefs. Result is a compression ratio from about 11:1.

Valve clearence is on the safe side but i don't have the figures in mind right now. Let me check my notes.

All valve spring seats are machined and shimmed to get the same compressed spring hight, +/- 1/10th of a millimeter tolerance.

The rockers are scorpion rollers with 1:1.7 ratio

I think You don't have to be afraid as long as "The Butchers" hints are followed.

The gear problem was caused by my high oil pressure setting. It was not 114 as i wrote before, it was up to 140 PSI cold!!!

So check your distributor gear with the butchers instructions in hand and don't worry.

If somebody would be interested maybe I would start something like a cobra build-up report pictured more or less completely.

Cheers,

Uwe

[rdorman]

Thanks for the information. I now have about 12,000 on my Cleveland. Run 5W-30 Mobil one in it year round. Hot pressure it 30+-, Cold is 80+ at fast idle. I think the pressure relief is around 80 or 90. Plenty of pressure. Picks up 8 or 9 pounds per thousand. I took a main cap and rod cap of a while back, bearing look like new.

Ready for Oktoberfest? We have a big Oktoberfest party this Saturday!

Rick

[westcott cobra]

I'm getting nuts.

Engine is right back in the car with new cam, new distributor gear. Distributor length is measured it's not binding in the bottom.

Everthing looked O.K.

Pressure relief was set to 90PSI cold.

Car has now 90PSI cold, 75-80 PSI warm at 2000 rpm.

But......................95-100 PSI warm at 3000 to 3500 rpm.

100 PSI is the max even with 6000 rpm on the meter.


I think it's the HV Oil pump which is setting the 20 PSI higher end result warm.

Oil is 5W30 synthetic. Oil filter is a Moroso racing with very low flow resistance.

Should we open again the oil pan and decrease the warm pressure at 3000 rpm to 70 PSI????

Oil pump is still adjustable.


Cheers,

Uwe

[wilf leek]

Personally, I would set the pressure relief to 80 psi to avoid a repeat performance of your previous problems.

It looks as tho' it is set at 100 psi now, and as the revs pick up and the pump generates more pressure, that is what you are seeing.