Std Bore needs to go .040, possible?

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dodge freak

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Found a non running 1972 340 with std bore and bearings--date coded May 72, just like the block. Had no rust on the cylinders but heads looked to been done a few times. Machinist said it had to go .040 cause of the taper. Said no way .030 will clean it up. Its all done but been thinking about it. Does that seem possible or pretty unlikely.
 
I have seen more 340s that needed .040 overbores than 360s and I have worked on engines of all kinds for 30 years.Yes its deffinitly possible more than my spelling!
 
He told you due to taper. So it's either you believe him or you don't. If you have your doubts I'd will say if that original block was really tapered more thna .015 there were some major issues with it. What equipment does he bore with? If it was an oldschool bar he may have bored it on an angle by mistake and neede to go to .040 to fix it.The 410 I just did went from .030 to .040 over... Because I wanted a straighter rounder bore with the right finish.
 
..............I have seen more than 1ce that an engine wouldnt clean up at .030..........i had a .030 that .060 didnt true it up perfectly............kim.........
 
I wouldnt worry about it at this point. It's all together, right?
 
moper said:
I wouldnt worry about it at this point. It's all together, right?
Click to expand...

Very good question, lol. I'm heading down to the shop in the morning. Guy said on Thursday it could be ready late Friday and I told him I can't get it til Monday, he said good cause I have 3 other ones to do..hes got like 4 or 5 guys with him. So its to be done Monday afternoon...I hope the crank was at least installed by now. Its just a short block

Seems so easy I could do it but then if a problem comes up later on
 
Easy to check taper with a set of new rings and feeler gauges.
 
You're talk .005" in each side of the cylinder. IMO, it's not a big deal so long as the thing's got straight round bores now. One of the reasons I align hone everything and use the shop I do is because the modern equipment can fix factory machined angles and cylinder placement but it indexes off the cam AND the crank centerlines in one shot. Then when it's decked it's definately 90° to the crank centerline which is 90° to the cam and bell housing flange, and the holes are spaced where the engineers wanted them. There are some really bad blocks out there in terms of bore centerlines...lol. The old boring bars simply center themselves on the existing hole, and the machinist levels them to the deck. So when something is off originally, the older equipment basically exagerrates the error unless the guy is ultra-ultra anal and takes some time to verify everything.
 
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