So, I have got the engine report back from Dan at Stubbs Racing Engines......
He got the big block fully stripped down and reported it's not good news, however this is some positive !
The engine is on a standard bore size (this is extremely rare for these engines now) so this is good news and the engine looks like it has never been apart before so this is good. It even has the original General Motors bearings and Pistons etc, it's all original ! Also the engine is a 4 bolt main block so it is one of the strongest Big Block Chevy's GM ever produced. This casting number is typically high in nickel content which makes them strong !
He has rebuilt countless Big Block Chevrolet engines and only ever come across one other that was totally standard with a standard bore size.
Cylinder number 6 has a spun connecting rod bearing. This would be the bottom end noise. Unfortunately it has damaged the crankshaft beyond repair and the crank will need to be replaced along with all Connecting rods as the rotating assembly has been subject to extreme heat. He also found 4 broken piston rings. The bores are worn and the block will need a Re-bore and hone along with larger pistons and rings. Also recommend skimming the deck surface of the block and the cylinder heads to ensure a good head gasket seal. It will need new main bearings, con rod bearings, cam bearings. To add insult to injury, running the engine for only a few minutes a, few times, rather than going through the cam break in process of running it fast and hot has damaged the new cam and lifters.
So to recap the engine does need a full rebuild. In actual fact to say its never been rebuilt/opened up since it was originally built it hasn't done bad was the verdict.
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I am shocked by how much metal there is in the oil pan. I checked the oil that came out of the car and whilst here were a few traces of metal glistening in the oil it was in keeping with what might be expected from the cam and lifters that had worn. The oil pan was spotless when it went back on the car after the cam was installed and the car ran for no more than 10 minutes in he garage.
I do wonder if the bottom end has been failing for some time and got to a critical point of heat build up on the M1.
The car is going to be off the road for a month or two longer while this is sorted.
