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Engine gurus, I need some advice, please.

My brother purchased a '68 w/ 302 about 6 months ago. The previous owner claimed that the engine was rebuilt with approximately 25k miles. It is a 2v car that had a factory 4v intake and carb installed. My brother decided he wanted to dress up the engine bay, so he installed an Edelbrock Performer intake. However, he used the incorrect intake bolts. The result was that he ended up driving the car about 100 miles with water leaking into where only oil should be. He re-mounted the intake with the correct bolts and all seemed to be well. He had become frustrated lately with the fact that the radiator level always seemed to be low, yet he never did see any oil in the water or water in the oil and the car did not run hot. He found one spark plug that was completely clean, where all the others were somewhat dark, so he assumed that water was leaking into that cylinder and blowing out the exhaust. So, he pulled the heads and purchased a set of Rousch 180s to replace them with. He also picked out a mild crane cam, and when he pulled the old cam, found that the cam shaft bearings were completely worn out, so much that the old cam was moving around in the bore. He is convinced that the motor has at least 60k plus miles and that he has been taken. The motor is heading to the machine shop, now.

My brother was a chief Engineer aboard coast guard ships for 20 years, so he has lots of engine knowledge. But, given that the ships are diesel, I'm interested to hear the opinion of people who have more experience with ford small blocks engines. Do you think 100 miles of water in the oil could completely wear out cam shaft bearings, so much so that you can see the brass?

As always, thanks for your opinions, gang.
 

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For that much damage to occur in 100 miles the oil would have closer resembled a chocolate milk shake... Sounds like the rebuild was probably done without inserting new cam bearings, or no assembly lube was used during assembly.
 

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I disagree with the other post. If there was a good concentration of antifreeze/coolant in the mix this will wipe out bearings faster than....well, real quick.

Here's an excerpt from an antifreeze manufacturer touting the benefits of propylene glycol over traditional ethylene glycol:

According to Arco Chemical Company (Document OP88-791-7.5M "The Facts about Propylene Glycol Antifreeze"), "PG-based antifreeze has shown reduced risk of bearing damage if introduced into the oil by head gasket leakage or failure. A Detroit Diesel 8V92T engine was run on a dynamometer for one hour at full horsepower (432 HP) with 8 percent [propylene glycol antifreeze] poured directly into the crankcase . . . no excessive wear was shown on bearings run with the 8 percent PG coolant when the engine was torn down." In contrast, "one-half to one percent of ethylene glycol in the oil causes rapid bearing failure, resulting in the shutdown of the engine."
 
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