Shredded Bronze Distributor Gear

[bobfake]

Hi all,

I had someone approach me at a Cars & Coffee the other day. Said he was having an issue with his '70 GTX 440 6-pack. He asked if I could stop by and take a look for him. He is not mechanically inclined.

I did stop by and I noticed that when he bumped the motor over, the distributor didn't spin. I pulled the distributor and could see the bronze (I believe) distributor gear was shredded. (See pics). He said he has less than 2,000 miles on this build (which someone did for him).

I believe that since there are pieces of this gear throughout the engine, that at a minimum, the intake and oil pan need to come off and, if possible, flush the oil passages to get the shavings out.

More likely the whole engine needs to be disassembled and cleaned.

Can I get your thoughts on this please?

Thanks!
Bob

 

[snakeoil24]

Your fingers are covering the shaft so I slightly see wwar and bet it's bent. I would replace the bushing in block and since the pil pump is outside pull it and disassemble and look at rotor lobe. You should know these drive gears do have short lives but also if it was used with flat tappet cam then cam needs to be pulled and cam bearings should also with lifters be replaced as well.ive never seen these used with anything but roller cams. Another issue is the cam or push rod for fuel pump bent? ALSO I SHOULD ADD HE WILL NEED TO SWITCH TO A HARDENED DRIVE GEAR LIKE THE ONE HUGHES SELLS

 

[zyzzyx]

Since the oil pump takes the oil from the sump, pressurizes it, and then sends it through the oil filter before distributing it to the
engine, he can cut the oil filter apart and look for how good of a job the filter did. Take the valve covers off and see if there is any
"shimmery stuff". He might have been really lucky! If there is evidence of the bronze gear scattered throughout the engine, then
yes, the engine needs to come apart. Bronze embedded in the babbitt bearing material will wear grooves in the crankshaft!

 

[493 Mike]

How often should the bronze gear be inspected? I have read that the melanized gear should not be used on any used cam, only brand new. Any experience from racers? Thanks!
Mike

 

[DanielSlocum]

perhaps there is a roller cam in there and the end play was not set properly with a thrust button resulting in the cam trying to walk forward thus eating into the softer bronze gear?

 

[snakeoil24]

perhaps there is a roller cam in there and the end play was not set properly with a thrust button resulting in the cam trying to walk forward thus eating into the softer bronze gear?

For sure this is possible

 

[beanhead]

perhaps there is a roller cam in there and the end play was not set properly with a thrust button resulting in the cam trying to walk forward thus eating into the softer bronze gear?

That could be. Whatever happened, it isn't from normal wear.
Another possibility--and maybe this is out in left field--but if the distributor didn't spin when the engine was bumped, maybe the block bushing was never sized or burnished, the drive shaft was too tight, and things worked okay for a while until the the gear teeth could no longer take the extra pressure....and of course the cam still wanted to turn at full speed so it finally sheared them at the contact points.
I'd be taking apart the oil pump as well, to see if maybe something got in there and caused it to bind.
Sucks for your friend either way, hopefully the rest of the engine is okay.

 

[Geoff 2]

Let's get some of the BS out of the way.
The original factory pump drive was case hardened. Try cutting one with a hacksaw....
The problem was that though they had good wear properties, they were brittle....like a drill bit, didn't like shock, such as from a high pressure/volume pump. The shaft also terminated abruptly at the hex, creating another failure point.
Chrys then made available the 'high perf' shaft which was made of hard steel [ I believe it was 4340 Moly ], but not hardened. This steel is softer, can be cut with a saw. It will also wear more quickly using a bronze bush; alum bush is better. The hex/shaft interface is also tapered, with no sharp points to cause a fracture.

There are different grades of bronze also.
If you don't want a bronze gear failure, use a Melonized gear which can be used with all types of cam.

 

[lewtot184]

Bronze gears are the sacrificial lamb of the roller set up. There are factors that accelerate wear but in the end, sooner or later, they take a dump. I believe when using a bronze gear on a regular basis they do need to be monitored.