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picked up a 350 chevy 4 bolt block 3970010,cast and assebled in 1975, was reading up on chevy small blocks, it said the samll blocks with high nickel content had a 10 or a 20 cast into the block under the timing chain cover, on my block there is a 020 cast into it but there is 4 or 5 other numbers cast right above it, just wanted to know if it was a high nickel content block or not, i read they stopped doing that after 1973, but that was in a small block mopar book.
thanks
Russ
probably the best blocks to get have the 010 or 020 under the timing cover. What these numbers mean is that they have 1% tin and 2% nickel.The tin is used to help the molten iron pour and flow better into the mold. These numbered blocks are the least prone to cracking. Because they pour more easily, they also have less pro0blems caused by hot spots that is caused by porous metal. The nickel that is in the blocks work hardens as the engine heats up and cools down this makes them more resistant to bore wear.
If your block only has the one set of numbersthat are either a 010 or 020 this will mean that there is no additionally added tin but it does have the 1 or 2% additional nickel. If there is no number on the block of coarse that means there is no additional tin or nickel, so these blocks can be expected to wear out faster.
So this should help you work out what you have got.:D
Most of the "higher nickel" blocks that I have found came in 68 to 72 Chevy and GMC trucks.Quote:
Originally Posted by chevy427tall
These early blocks where also a little heavier in weight compared to the blocks made in the middle and late 70's
If you look at the area around the bell housing where the bell housing bolts go in to the block on some there is a lot of material missing.
If you use these 4-bolt blocks I would try and keep the hp less than 550.