300 I-6 timing gear

Hey, all, I have an old Ford dump truck with a straight 6 300 (it's an
F-500 from 1970). I got it used a few years ago and it knocked pretty
badly and finally threw a rod yielding a viewport on the side of the
block. I replaced the engine with a rebuilt one from a machine shop
I've had good luck with in the past. I don't use it often, it
probably has less than 1,000 miles on the engine but it's past the 12
month warranty. Recently it quit running, leaving me on the side of
the road. Today I tore into it and found the phenolic timing gear was
stripped of all but 5 teeth. This wouldn't bother me so much except I
had a 1986 F-150 with the 6 in it strip that gear. That was an old
engine and I found that the oil pump pickup tube had some junk in it
and I ASSUME that junk was sufficient to block the oil pump and strip
the timing gear (which drives the cam which drives the vertical shaft
which drives the oil pump and the distributor). I hate coincidences
and this bothers me; two gears on basically the same engine, one used
(that one in the old F-150), one new (the rebuilt engine in the
F-500). What's worse is that I checked the pickup tube on the rebuilt
engine just because I had that past experience.

Has anybody got a, "Oh, hey, here it's this!" answer to the problem?
Any pointers on what I should look at or for? I don't want to replace
the gear without understanding what caused the failure because it
could happen again all too easily.

Thanks for your help and advice.

--HC

"HC" <hboothe.DeleteThis@gte.net> wrote in message
news:4914c8c5-ca97-4e69-a6f0-e874444525d5@f18g2000vbf.googlegroups.com...
> Hey, all, I have an old Ford dump truck with a straight 6 300 (it's an
> F-500 from 1970). I got it used a few years ago and it knocked pretty
> badly and finally threw a rod yielding a viewport on the side of the
> block. I replaced the engine with a rebuilt one from a machine shop
> I've had good luck with in the past. I don't use it often, it
> probably has less than 1,000 miles on the engine but it's past the 12
> month warranty. Recently it quit running, leaving me on the side of
> the road. Today I tore into it and found the phenolic timing gear was
> stripped of all but 5 teeth. This wouldn't bother me so much except I
> had a 1986 F-150 with the 6 in it strip that gear. That was an old
> engine and I found that the oil pump pickup tube had some junk in it
> and I ASSUME that junk was sufficient to block the oil pump and strip
> the timing gear (which drives the cam which drives the vertical shaft
> which drives the oil pump and the distributor). I hate coincidences
> and this bothers me; two gears on basically the same engine, one used
> (that one in the old F-150), one new (the rebuilt engine in the
> F-500). What's worse is that I checked the pickup tube on the rebuilt
> engine just because I had that past experience.
>
> Has anybody got a, "Oh, hey, here it's this!" answer to the problem?
> Any pointers on what I should look at or for? I don't want to replace
> the gear without understanding what caused the failure because it
> could happen again all too easily.
>
> Thanks for your help and advice.
>
> --HC
That was not an uncommon problem in the 300I6. The solution is to replace
with an alloy timing gear. I have one in an 82 F250, the phenolic gear
lasted about 180k and was still useable but I replaced it when I rebuilt the
motor.

Dave D