I'm in the position to pick one up for $500 and I was wondering what is the difference in them all?
What's so great about a 4 bolt main 350 chevy?
Jun 21, 2005
9 Replies
2 bolt main = main caps are held on by two bolts each
4 bolt main = main caps are held on by 4 bolts each
4-bolts are supposedly stronger and can take more HP in super-high output applications, but for a stock motor or anything up to 350 HP or so a 2-bolt does just fine.Doc
I found this article that helped. Thanks for your responses.
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Actually I would say about 400 HP and about 6500 RPM or so. If you plan to exceed these levels regularly I would go with a 4 bolt block. ALso I would not supercharge a 2 bolt block either at any HP level.
I hope your not paying $500 for a bare 4 bolt block, i get them all day long already prepped...tanked, magged, decked and bored +.030" for $350 Add another $700 and you get a balanced and assembled 383cid short block with a Scat crank, 5.7' rods and Keith Black pistons, externally balanced
168 tooth flexplate and harmonic balancer.....
Where can I get one for that price? Is it a long block at that point?
Larrys Performance shop in Montebello,Ca.
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it's not a long block at that point...It's a fully assembled short block with the cam of your choice.They are building a zero deck 383cid short block for me right now with 4-bolt mains, 6" rods and raised ring hyperuetectic pistons with a 18cc dish, slightly more expensive than your basic 383 stroker motor but well worth it.
5.7" rods with a 3.75" stroke gives you a 1.52:1 rod ratio......
6.0" rods with a 3.75" strokes gives you a 1.6:1 rod ratio..... The ideal rod ratio is 1.75:1...... my goal is to combine the high revving attributes of a 350 with the brute torque of a 400. For more info on rod ratio and bore/stroke ratio please visit these pages
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another great link for ya..
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How can I tell if its a 4 bolt with out taking the oil pan off?
If it is a Post 82 or 84 Block it will have the Displacment on the drivers side of the bellhousing flange, older blocks have a casting number there. Newer blocks have a casting number on the middel of the bell housing flange. Run those numbers. There is also a pad by the waterpump that has numbers punched in it. Between the two sets of numbers you can tell what it was orginally in, 2 bolt mains vs 4 bolts, orginal HP & Torque Output. Charles
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