Dave W 1971/240Z rebuild

[grannyknot]

Well not a moment too soon for the bearings, at least they did their job and sacrificed themselves because the crank journals aren't that bad.  I'll still send the crank out for polishing.

Because the engine has been sitting for so long I gave each shell a couple of swipes with a scotch pad to bring out how much much copper is showing, these could have spun any moment.  First pic is the rod bearings, second are the mains.

The crank is showing some water marks and some copper transfer.

Knocked out the freeze plugs and found lots of crud and silicone sealer clogging up passages.

 

[Racer X]

Pretty sure the marks on the combustion chamber and piston are mechanical damage caused by a foreign object. It could have been a spark plug electrode that broke off, or something ingested through the intake.

I’ve seen both mechanical damage from foreign objects, and detonation damage which will have severe burn marks where the piston and/or combustion chamber begin to melt accompanied by mechanical damage such as broken ring lands and broken rings. 

This hemi ate a valve during a pass. There was damage in every combustion chamber. There were bits of broken and twisted metal in the intake and carburetor throats. 

 

 

 

Edited July 15, 2023 by Racer X

[Patcon]

Yeah, those bearings weren't long for this world...

[grannyknot]

7 hours ago, Patcon said:

Yeah, those bearings weren't long for this world...

But even with all the trash that scored up the bearings, the oil pump is in very nice shape. As far as I can tell, the engine has seen light use but a lot of neglect, I'll bet most of that wear happened on startup with old dirty oil. I rolled the block outside yesterday, removed the plug sealing the main oil passage and scrubbed every hole with bottle brushes, lots of oil sludge in those lines.

💡 Could have been an obstruction in the line leading to oil starvation!

 

[grannyknot]

I really don't like dropping off a crankshaft to be polished, very few machinists do it in house anymore so they job it out to a 3rd party that doesn't deal with the public.  Once they have it, it can sit on their floor for months before they get to it.  So I thought I would have a go at it myself, I started with 1500 wet/dry paper, lots of WD40 and an old shoelace.

Spent about 2 min per journal, then cleaned it off and made a long strip of an old T shirt and some Autosol polish, about 1 min per and I'm done.

Edited July 15, 2023 by grannyknot

[grannyknot]

After having saved some of the budget on the crank, I thought I would have a go at the broken exhaust studs, ah a few more dollars saved!

Also got some painting done today and added some bling to the engine block.

 

 

[zclocks]

Question. How did you remove the broken stud? 

Ron

[grannyknot]

55 minutes ago, zclocks said:

Question. How did you remove the broken stud? 

Ron

The second pic down I've welded a blob on top of the broken stud, 3rd pic I rest a nut on top of the blob and weld those together, quench it with WD40 and unscrew it.

Most of the work is done by the heat.

[Mark Maras]

I didn't recognize the hot nut at the time. thought maybe you'd sprung for a Malibu Barbie Easy Out.

[Patcon]

I couldn't tell that was a blob of molten metal on my phone

[zclocks]

Ok, I get it. I couldn't tell what the pink thing was, It's a red hot nut. duh!!

[grannyknot]

It's a trick I've heard about but never got around to trying before, it didn't take 2 min to do, no good on a cast iron block of course.