Not my engine but curious

[edgarval]

It's not my engine . It's on Facebook . The timing dowel pin broke off and damaged the bottom end ,that is the story I heard on it . Have you guys seen this before ?

[blykins]

Dowel pin was an effect, not a cause.  Dowel pins don't hold everything together, they are used for alignment and the clamping force of the bolt keeps it all in place.

My guess is that his cam bolt wasn't torqued or wasn't the right length, or it started when it spun that rod bearing and then the rod fouled the cam.  Most possibly the latter, as usually when something with the timing chain/bolt/etc. fails, the engine won't run long enough to trash the bottom end.

[fekbmax]

I'm with Brent on this one. I think the pin shearing was the effects of another failure.  I have beat the hell out of some FE's for 34 years now, built alot of decent stuff and my fair share of junk from old used parts and hammered the hell outta them. Sheared 2 pins. One swallowed a dumbbell solid lifter and hung the cam. That was a super low budget engine. Only time i ever seen the lifter bore completely break out. Second time was a dropped valve, completely dropped from the head, hung the engine up solid, factory rod looked like a horseshoe, trashed a A scratch block.
I will say though that even though i don't think the pin failed first, i have been dbl pinning my junk for many years now.

[jayb]

I would just echo the previous comments, and after looking at that piston and rod picture it seems to me that it was certainly a reciprocating assembly failure that started the whole mess.  Spun rod bearing would be a likely starting point...

[edgarval]

Thank you guys for the knowledge .

[scott foxwell]

Yep. Everything above x2.

[gt350hr]

  Look a little harder at picture #1 . The cam thrust plate bolts should NOT have washers . The problem began there. One was rubbing for sure.

[jayb]

No way that caused the connecting rod failure shown in the photos.  And if I recall correctly, the factory Philips head screws that were used to hold the cam retaining plate in place did indeed use lock washers.

[gt350hr]

   Sorry Jay,
       I missed the heat marks the rod on picture #4 . I was looking at the heat discoloration on the end of the cam. Thought maybe it was trying to weld the gear to the cam. Figured the out of time cam crashed the valve and caused the rest. Probably broke the rod first  now that I see the heat on the remaining rod.

[scott foxwell]

Dowel pin was an effect, not a cause.  Dowel pins don't hold everything together, they are used for alignment and the clamping force of the bolt keeps it all in place.

Most BB Fords I've worked on with solid rollers and spring pressures require either a keyway or dual dowel pins. One dowel pin doesn't cut it and either does the clamping force of the bolt. I don't think it's what caused the problem here, but I'm just sayin...

[C6AE]

A quality 5/16" dowel pin has 10,000 psi shear strength. Two of them is 20k...
I wouldn't expect bolt clamping force to come anywhere near those numbers.

[blykins]

Clamping force on a *good* 7/16" cam bolt torqued to 70-75 lb-ft would be 14000-15000 lbs. 

I'll be honest, I've double pinned cam gears myself but it was for extra insurance with 800-1000 lb valve springs. 

Key points are a good solid/thick/hardened washer and a correctly torqued camshaft bolt. 

[scott foxwell]

Clamping force on a *good* 7/16" cam bolt torqued to 70-75 lb-ft would be 14000-15000 lbs. 

I'll be honest, I've double pinned cam gears myself but it was for extra insurance with 800-1000 lb valve springs. 

Key points are a good solid/thick/hardened washer and a correctly torqued camshaft bolt.

Clamping force is only as good as the amount of surface area being clamped.

[blykins]

Then you turn it into clamping pressure.....

[Ford428CJ]

It did take water in that hole....