Quote:
Originally Posted by 77 TRASHCAN
Can the bosses be drilled and tapped, to use the early mounts?
|
Although some of the late blocks had the bosses, most didn't have them. Usually there aren't any there, they were eliminated from the mold patterns.
I have seen maybe a couple late blocks where the metal was still cast, and could be drilled and tapped, but for the most part, there is no cast metal there.
I believe some early 77 blocks still had the metal there, but soon after it was eliminated. Just my thoughts. I don't have any documentation to substantiate that, but most of the late 3 bolt blocks only have 3 bosses, not 5. don't forget, 77 was the year GM started cutting any metal they could from the engine to try to meet CAFE standards.
I still remember the first time I pulled the timing cover off of a 301, and noticed the timing chain was thinner. they cut 2 rows of links off of the timing chain to reduce weight.....
Lost the counterweights on the 301 crank, and trimmed the balancer to almost nothing. they also cut huge triangular slots in the flex plate instead of the previous 6 holed flex plate. The 77 flex plates cracked very easily with only 3 spokes holding the ring gear to the crank. The changes were just a few grams here and there, hardly enough to make a difference in fuel mileage, but enough to cause reliability problems, along with cutting the nickel content in the block made them less wear resistant.
Then they took so much metal out of the block, the main bulkheads, and caps were prone to cracking. The famous 557 lightweight block was costing them warranty money, so they brought back the old casting in 78. Come to think of it, the heavier duty 78-79 block may be the ones with the 5 bosses cast in, with only 3 tapped....
