Learn from my pain
What happened?
Looks like a series of unfortunate events, all induced by me. ONE: I was in a quite awkward position, with limited visuals. Had I been doing this correctly, engine out of the chassis, on a stand, standing in an upright position with good lighting, I would have seen that ‘doesn’t quite fit’ cap. TWO: I should have noted the lack of Numbering and alignment (I did note it, just was confident that I could keep things in order, NO, Doesn’t work like that.) and I had the tools to make marks of my own, and failed,,,, That failure is evident now, ain’t it? THREE: Don’t get in a dag-blamed rush!!! My desire to get this twuck on the road and doing me service has done me a DISSERVICE, as well as a potential TOTAL FAILURE. I do not know that I can find an adequete replacement cap. Looking online, NO ONE sells them. I have an option in Donor Truck, maybe, IF I’M FRELLIN’ BLESSED IN THIS LIFETIME,,, Yes, the dimensions are the same: does NOT mean the bores are identical, (updated: sis find online and no donortruck parts wont work, not in this case. Maybe for Buffalo ,,,)
And I need to get the parts out to compare them and you can believe I am going to be comparing them with MEASURING TOOLS from my machining stuff. NO GUESS WORK HERE, NOT THIS TIME.
FWIW: I pulled the cap off #4 and suddenly, the whole thing spun FREE,,, It was not prior, though it was moving. So, my issue was swapped out #2 and #4 main caps,,, And the fact that that cap is busted like it is,,, It likely was cracking when I torqued it, but still things were still moving sorta freely at that point. When the crack let loose, was when everything clamped tight.
Can that cap be repaired? Yes and no. Yes, it could be, but would it ever be right again? Hard call that. I could press it to close the cracks, open the edges of the cracks up with a diegrinder, and TIG them. BUT, there is a lot heat involved and steel SHRINKS when exposed to that sort of heat. SO, the question at that point, would it shrink enough to tighten that journal more and need to be rebored? Likely. VERY likely actually. I haven’t the means to rebore a crank tunnel. And the whole engine would need to be pulled to do so.
You see where all of this is going don’t you? Shoulda paid attention, not just to my actions, but to the words of those wiser than myself.
Learn from my pain.
Live
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LOAD!
(side note: none of the bearings show any adverse wear from this little snafu. All clean and polished as if new. That Pre-lube did something right. Also, none of the bearings, with the exception of #2, had any of that crap on them when I pulled things apart. Even the Rod-ends were clean of it, so the oil drive DID clean it out. )
Dio's Workshop 
Don’t beat yerself up too bad – that coulda, woulda, shoulda stuff will make ya crazee!
And yer correct – the en-jine would hafta come out, and a new cap procured (maybe all), and the thing line bored, to be sure they’re all correct. That crank is purty particular ’bout having a straight hole to spin in. Then, ya gotta be concerned that the machine shop knows what the fuq they’re doing.
No ezy option, here, I’m afraid. I’m presuming that ya have an inside mic for yer machining tasks. You’d hafta install a different cap, mic the ID, and compare that with the actual specs. Not terribly hard to do, but hasta be right. And if not, back to the line bore. Seriously large amount of work there. Dam, if’n I had a 350 sitting around, I’d give it to ya, to save ya some work!
Y’all take care,
Mike in FLA.
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December 14, 2025 at 5:25 pm
Yup. I have the bore mics, 1/2″ -6″ set. Not gonna be able to use donor truck parts. 2 bolt mains ,, keep lookin!
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December 14, 2025 at 5:27 pm
Shoulda thunk about it before – but under NO circumstances would I (just me, mindja) try to do a repair on the cap, even tho I can do the welding part, too. You’d still hafta get the thing line bored to be sure.
Y’all take care,
Mike in FLA.
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December 14, 2025 at 5:31 pm
Agreed!!!
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December 14, 2025 at 5:32 pm
Are you sure it’s steel and not cast iron? I don’t know myself, and like I said in my last comment, the one time I tried to weld a casting I screwed it up so bad I had to buy a new hydraulic cylinder. I screwed it up by the numbers! If you shrink it a little bit, you could resize it with a brake hone. I know that’s straight up redneck but getting it back together and functional is the objective.
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December 14, 2025 at 9:10 pm
Its cast,,, I use the terms interchangably, but I do know the difference. You were correct, check my other comment for details.
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December 14, 2025 at 9:14 pm
Your not chasing unicorns. Your back is against the wall in a shitty situation. You’re trying to bring all the puzzle pieces together so your future is better. On a positive note, you’ve got way more skills than a lot of people. I think you can salvage the situation long enough to put yourself in a position to replace the engine. How long will your repair last? God knows, I don’t. But all you need is a couple of gravy jobs to cover another block. You’ll recover. You’re alive and breathing, you’ve got tools and skills, you’ve got a network of people to back your play. And if the repair goes well, you’ll have the breathing room to build another engine and have it ready to swap out at your convenience. It’ll work out. One way or the other, it’ll all work out.
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December 14, 2025 at 11:16 pm
If you opt to weld it, pretend it’s sheet metal and weld a little at a time. Spread the heat to reduce the deformation.
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December 14, 2025 at 9:13 pm