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Old 05-23-2020, 10:20 AM
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Field checking a used engine block ...

Hi Guys,

I have two Chevy big blocks I am going to check out. Hoping you guys can lower my chances of buying boat anchors. These will be for rebuild.
I know I can check the deck with a straight edge, look for obvious cracks, damage to the cylinders, etc.
Basically looking for stuff I can check out in someones garage without getting out precision measuring tools. Two 2 bolt big blocks, guy is asking $200 each.
Check list, videos (previous posts, I did do a quick search ..), anything to help.

Side question, two bolt vs four bolt HP limits?


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Old 05-23-2020, 10:38 AM
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Looks like you've covered what can be done without a Magnaflux for cracks...
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Old 05-23-2020, 10:51 AM
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An eye ballcheck is about all you can do, besure that all the main caps ate thete and in order. Out of order may indicate that they are not from that block as much as careless reassembly. Not native to the block leads to heavy corrective machining, missing caps do the same thing, the cost of which isn't cheap.

Beyond that you puts down your money and takes your chances.

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Old 05-23-2020, 10:57 AM
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HP limits on a 2-bolt block, they'll go up to 650hp area , helps reliability to internally balance them.

A simple pair of $10 Ebay digital calipers can check bore size if the heads are off.

Visual check for obvious cracks is about all you can do, but that won't catch cracks only a magnaflux will show....buying used blocks is always a crapshoot in this regard.

Checking decks for flatness won't mean much, cutting the decks to get them square and parallel to the main bearing centerline is a common hi-perf machining practice...from the factory they never are good.
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Old 05-24-2020, 02:57 AM
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If they are carb to pan motors I would take that deal without a second thought.

Turn them over by hand to make sure you do not have a busted rod or something major. But outside of that they can be run on a stand and sold to someone wanting a replacment for a farm, wood, or mud truck. It may have some bad oil seals and smoke a little. But if it runs it will sell.
I buy both for $400 put $50 into one of them so it can run on a engine stand/bucket. Sell that one for $500.

Now you have a "free" big block to build into a 468. Or you can get that 454 into running condition for $50. Sell it for $500 and pocket the cash for the next deal that comes along.

If you are just talking about short blocks sitting on the floor of a shop that is $50 for a sbc and $75 for a bbc in my book. If it is something "special" like a BOPC shortblock I will go $100.

I am cheap and will spend cash only if I see a way to make a profit. There is really no way to recover $200 from a shortblock with pitted cylinders. If it is a longblock you have the carb, intake, manifolds, pan, waterpump, alternator, and $75 shortblock to recoup that $200.

2 shortblocks alone for $400 is not something I would waste time on.

Buy a entire running bbc for $350 to $550 to build or run. You can peek a camera inside and run compression checks on it to see that it is a good engine right on a shop floor if you gave concerns.
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Old 05-24-2020, 07:29 AM
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BBC have open holes into a coolant passage for the head bolts.Dont forget to look at them to be sure they have threads left in them.I have had a few that had little thread left and pulled out when torquing down the head. Timeserted them for a repair .Just saying.

Also not a bad Idea to check all bolt holes , especially starter pad bolt holes.
Fact is stranger than Fiction
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Old 05-24-2020, 07:56 AM
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...and now that you've received this useful information you'll have to report back to us to tell us how you did!

Good luck!

Ken in SSF CA
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