Quote:
Originally Posted by DAWG
The later blocks had more metal around the main webbing area, so they're "stronger". People talk about "4-bolt" vs "2-bolt", but that's not really the difference; the # of bolts is incidental. It happens that the factory put 4-bolt caps on the early ones and 2-bolt caps on the later. But the REAL difference in the blocks is early vs late, not 2- vs 4-bolt. The bolts themselves aren't what makes the ones "better" than the other.
You'll get best results with a small chamber head (64cc) and pistons with a small dish or (ideally) a "reverse dome", to put the ACTUAL CR (calculated including the ACTUAL MEASURED deck clearance) in the high 9s if the heads are iron, or mid 10s with aluminum heads. Deck clearance is CRUCIAL: don't be fooled by the "catalog" CR listings, or just "assume" that there is no deck clearance. With most "rebuilder" type pistons including TRWs for example, the deck clearance, which is how far "down in the hole" the pistons are at TDC, can be nearly .050" in some blocks, which in turn can cause the ACTUAL CR to be a full point lower than some randomly guessed and "calculated" CR. Any CR calculator is only as accurate as the numbers you put into it.
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So are you saying all the 400 SBC's are 4 bolt blocks, and in the 509 and 817's they just installed 2 bolt main caps in the 4bolt block? so you can put 511 mains in a 509 or 817 block?
Good info dawg! what do you think you would get out of a 400 block with camel hump heads, 350/350hp 70 LT1 cam, and 650cfm holley with dual plane? I have lots of SBC parts from my step dads years. We have a few 350's around including a 4 bolt main 350 block that I was thinking throw one together this summer and put it in some beater car for fun.