[firechickenman]

That #2 dowel pin may have fallen out at any time since the pan was off the last time. Looks like the cap may have been moving around some. How tight does the dowel fit in the block?

Main studs should not be tight in the block. If you could remove the studs by hand after the nuts were loosened, that's normal.

Looks like you might have gotten very lucky. How did the oil pump drive come out of place? Is the shaft locating pin missing from the oil pump?

[Tom Vaught]

Originally Posted by firechickenman

That #2 dowel pin may have fallen out at any time since the pan was off the last time. Looks like the cap may have been moving around some. How tight does the dowel fit in the block?

Main studs should not be tight in the block. If you could remove the studs by hand after the nuts were loosened, that's normal.

Looks like you might have gotten very lucky. How did the oil pump drive come out of place? Is the shaft locating pin missing from the oil pump?

[ Post #1 FCMan: "car cut out on the track at 60ft mark. what I thought was something in the oil pump locking up and breaking the roll pin in the dizzy drive, turned out to be the oil pump shaft broken and a broken crank.

not sure what broke first, the crank or the oil pump shaft which then jammed the crank."]

The Number#2 main sees the stress in the engine first. Have seen several engines (cast main caps) where the #2 main cap was split up the main fastener hole. Your pics show no evidence of that happening in this case.

The crank does not normally break at the #5 main location.

Yours did which makes me think that the oil pump shaft got jammed up in the #5 crank counterweight area. If the block checks out you can put steel caps on the block is the block shows no other damage. Inspect the block for the oil pump shaft guide (cast in the block) still being there and in good shape.

Brian H broke the oil pump shaft guide on his IA-2 Block when he had a engine failure some years ago.

Tom Vaught

[461-69bird]

Tom

do you mean I shouldn`t use the existing main caps if the block is ok? also that shaft guide, what`s it made of?

thanks, Rick

[screamingchief]

I can easily see some excess heat (ie: blue'ing) in the area of the break around that rod journal/counterweight.

My WAG,it spit the OP shaft outta it,then it obviously lost oil pressure,rod grabbed the crank,bam broken crank,only odd part here is the OP says the rod bearing itself looked ok.

Was the big end of that specific rod discolored @ all???

That discoloration is away from (opposite side of) the main journal that has the thrust bearing on it,but despite that (one way or the other) I feel that the thrust issue could be the root cause of the crank breaking here.

Now were that the case,how about this chain of events,in this scenario the excessive thrust could easily be what took out the OP shaft,that's a no-brainer,that back counterweight is like right there,so that seems easy enough to see happening,I just dont think we'd see that obvious heat discoloration if the shaft jammed in there and caused the crank to break.

And the dowel pin is sorta the same deal.

I mean you can clearly see that specific main cap was fretting,and that's likely why the dowel fell out.

I dunno,looks to me like a couple of different things were going on @ the same time here.

Thrust is all outta whack,crank is sawing back & forth in the block,that causes the cap fretting situation first,so yeah it drops the dowel outta there,eventually the rearmost counterweight takes out the OP shaft,instant loss of oil pressure,then bam a rod grabs the crank,and the crank breaks.

Just curious,what casting no. is this block?

If it's a 557 block,that might explain some of this.



Bret P.

[461-69bird]

Brett

no this was a 72 block. all the con rod bearings were fine as were the crank journals themselves. yes the thrust bearings were worn but no other damage.

this happened at the 1-2 shift at 60ft mark.

I`ve had problems with it shearing the roll pins on the dizzy gear drive, would that have been caused by the crank moving due to the thrust wear?

[shaker455]

Originally Posted by Tom Vaught

If the block checks out you can put steel caps on the block is the block shows no other damage. Inspect the block for the oil pump shaft guide (cast in the block) still being there and in good shape.
Tom Vaught

Rick,
X2 on Tom's post....don't reuse the caps and get some steel caps.

If that's a 2-bolt block I'd consider splayed caps.

Either way sorry to see the destruction.

[johnta1]

I'd wait and see what the block looks like when tore apart.

I'd say the block is cracked somewhere in the main bulkhead.