The official FABO machinist/member collaboration, busted 340 thread

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And this the metallic grinding compound/oil mixture right out of the crank journal....

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replicaracer43 said:
Engine has the typical "old school" trw forged pistons, at .030 oversize with extremely heavy scuffing, and were in the cylinder at .005 piston to wall, the cylinders are all fairly even size wise, but 3 or 4 have almost. 002 taper, which is definitely no good.
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Do the pistons look new?

Can you tell if the piston and cylinder wall scuffing is from recent debris in oil are there before startup?
 
autoxcuda said:
Do the pistons look new?

Can you tell if the piston and cylinder wall scuffing is from recent debris in oil are there before startup?
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The pistons definitely dont look new for a engine with a supposed 80 miles on it. The scuffing is probably debris, but the mess at the top was probably poor honing of a rusted bore
 
replicaracer43 said:
Getting the rod and piston assemblies out, we find factory 340 floating rods, that DO appear to have been re-sized with new bolts. However they didn't bother with the wrist pin bushings, which are worn beyond tolerance. the crankshaft journals are worn severely undersize, and out of round, giving us a whopping .008 rod bearing clearance. Knock knock, whos there? Sad situation indeed!

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Can you tell if they were undersized and then polished before startup? Or did the recent debris in oil wear them out of round?
 
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replicaracer43 said:
The pistons definitely dont look new for a engine with a supposed 80 miles on it. The scuffing is probably debris, but the mess at the top was probably poor honing of a rusted bore
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This looks like a hone only job on a previous .030 over block?
 
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autoxcuda said:
Can you tell if they undersize and then polished before startup? Or did the recent debris in oil wear them out of round?
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The crank wont wear like that, in that short of time, the bearings take the brunt of it. My speculation it was worn out when it was installed
 
Does this motor have Eagle H-beam, stock, or aftermarket I-beam, rods in it?
 
@replicaracer43 regardless of who/why, it’s awesome of you for offering to help and documenting the tear down rebuild process for us to watch. Thanks, good on you.
 
I bought a 69 dart this 340 was in. Several years ago. I took it apart. Took the block and crank with the heads to machine shop. The bore was good. Just had it honed. The pistons looked new. The crankshaft was turned 10 under rods and Mains.new cam and lifters. New oil pump. Rebuilt kit. Heads all new. New water pump. New distributor gear. This is a very nice clean 340 . No striped bolts. The oil pan is very no dents. The engine stock compression 10.5. Stock cam .

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Hello, Thanks again Replicaracer43, This is one of the conversations from the GOLD member I bought it from. He has been on here for over 10 years. I picked it up Dec. 26th 2020, Kept it in my heated and cooled garage all sealed up. When I first got it I dumped break in oil in it while it sat till about april of 2022 and then I installed it and 1st tried to get it running. Primed it, before hand, etc. Thanks again to everyone involved, I bought as a supposed " just prime and go" I have more of the conversation #101 above
 
Dan the man said:
When rebuilding a engine, it doesn't always need to be bored. I don't understand why people think that it's not a rebuild if it's not bored. I knew a guy that rebuilt his engine with 50k on it and he didn't have it bored, why? Because the bores were in excellent condition and still had the cross hatch so why waste the money having it bored.
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If I ask you politely to stop hijacking this thread about THIS particular 340, would you oblige? Thank you sir
 
Digging deeper, is just more of the same. Absolutely the worst crankshaft wear I have ever seen, this thing is TRASHED

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And that tap was just left in the cam retainer plate, broken off. Nice. Cam bearings look like total **** too, but really, is anyone suprised at this point. I'm not

20220910_155538.jpg
 
Also the owner had just changed the oil, ran the engine maybe 5 minutes until pulling the engine. But sharp viewers will notice the engine never had the filter actually filtering anything.
 
Dont expect any miracles in the cylinder heads either. Worn old original valves, guides have been replaced sometime in its life with a plain iron repair guide, and they are worn out. Valve job looks poor on exhaust especially

20220910_160211.jpg
 
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