Thread: 302 Rebuild
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Old 07-16-2011, 03:05 AM
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07cob 07cob is offline
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Join Date: Jun 2006
Location: Palm Beach, QLD
Cobra Make, Engine: Harrisons # 62 302 T5
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Had some time today (its the weekend) to do a little more work on the engine.

With the damage to the top of the No.2 piston, I decided to remove the piston and check (a) for damage to the sides of the piston (b) damage to the big end - bearing or journal. Thankfully, the damage appears to be confined to the top of the piston and the mating surface of the head (as in the photos above). Here is the side of the piston:



There was also no visible damage to the bearing or the crankshaft journal for the No.2 big end.

With all this in mind, I am happy to agree with the two earlier conclusions (thanks boxhead and blykins), something has made its way into the combustion chamber and caused the imprints on the piston and head before being exhausted.

So with one piston out, it was little effort to remove the others and the crankshaft.



With all this apart, I measured the crankshaft bearing journals (connecting rod and main), the pistons and the bores and I am very pleased with the results. All were well within specifications for both size and taper.

Before removing the pistons and crankshaft, I also checked the big end bearing play and the crankshaft end play - again, both well within spec. All corresponding measurements were within tenths of thou of each other.

Next, I will be taking the block to be honed and will be replacing the bearings and the rings before it all starts putting itself back together.

Cheers


Geof
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