Re: Landry's Timing...

[jlandry@domain.elided (John A. Landry)]

In a brilliant stroke of genius, jmbrodsky@domain.elided blurted out:

>     of teeth is gone for about 200deg of rotation.  I'm hypothesizing that 
>     the teeth began to fail, one at a time (the two backfires) and each 
>     time a tooth broke clear away, the timing slipped one tooth.  The gear 

This is where I'm going to respectfully disagree with you Joel... your
hypothesis that is.  Now I'm no ASE certified mechanic (like John S. is),
nor am I an automotive design engineer, so I realize my opinion isn't worth
much, but I think your backfiring was something more like an intake valve
sticking open as a result of some valve train failure.  The valve train
failure caused the camshaft to want to stop turning resulting in the
catastrophic failure of the cam gear... apparently the weakest point in the
link.  If the gear were any stronger, it's possible the camshaft could have
been twisted in two or maybe some other valve train part would have failed.

>        I'll show it to you and you can guess too.  So far, every engine 

From your description, I have a pretty clear picture of what it looks like.
I'd made a necklace out of it and wear it to IH gatherings you attend.
When asked what happened, I'd tell everyone it was the result of building
an IH race motor that spun up so quickly the camshaft couldn't keep up!

>     now, and so should everyone elses.  Are you going to replace yours in 
>     the 392?  Look at the old ones VERY carefully and see if there is 
>     maybe just maybe a circumferencial crack beneath the teeth.

No... I'm not replacing the timing gears.  But I certainly will look
closely at the bases of the cam gear teeth with a magnifying glass.

>        I callzem like I seezem.

Yeah but what you didn't see may still be lurking in that engine... just
waiting until you are exactly 100 miles from the nearest gas station or pay
phone!

*Hopefully* it was some sort of simple fatigue failure of the cam gear and
nothing more.

Take care,

John L.

PS:  How many miles did the engine have when this happened?
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