Purchased bare SBC 400 today for 250.00. Casting No. 3951509, date is H 16 4 (August 16, 1974) and Vin ends CTU. Is this a good block to build? The block has recently been bored 030 (block is 4 3/16 inch), and needs assembly, no crank just bare block with new cam bearings and plugs. I'll need a kit to assemble. I have a pair of Dart Pro 200 alum heads (64cc) and a brodix dual plane HVH intake for use. Any recommendations? Thanks for input.
Sbc 400
50thstatenova
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Purchased bare SBC 400 today for 250.00. Casting No. 3951509, date is H 16 4 (August 16, 1974) and Vin ends CTU. Is this a good block to build? The block has recently been bored 030 (block is 4 3/16 inch), and needs assembly, no crank just bare block with new cam bearings and plugs. I'll need a kit to assemble. I have a pair of Dart Pro 200 alum heads (64cc) and a brodix dual plane HVH intake for use. Any recommendations? Thanks for input.
can you find out if it was honed with torque plates? 400 blocks have thin cylinder walls and really benefit from the TP hone.
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That's THE preferred factory casting. The "509" changed in around '76, about 10lbs lighter after that, GM removed material in the main webs, among other spots.
As Tom said, it's more critical that the 400 be torque plate honed than any other SBC.
Heads should be a good fit.
As Tom said, it's more critical that the 400 be torque plate honed than any other SBC.
Heads should be a good fit.
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Sonic check first.
In my opinion, 400 blocks benefit from a 1/2 fill, or even go to the bottom of the water pump hole.
But you say that the block is "4 3/16". That is 4.1875. 4.185 would be .060 over and most 400 blocks are too thin by the time you get to that point, at least too thin to start adding fill then correcting to bores properly. Stock 400 bore is 4.125.
To me a stock 400 block @ 4.185 is not very desireable. Sonic check it and check the bores before you spend a penny on it.
In my opinion, 400 blocks benefit from a 1/2 fill, or even go to the bottom of the water pump hole.
But you say that the block is "4 3/16". That is 4.1875. 4.185 would be .060 over and most 400 blocks are too thin by the time you get to that point, at least too thin to start adding fill then correcting to bores properly. Stock 400 bore is 4.125.
To me a stock 400 block @ 4.185 is not very desireable. Sonic check it and check the bores before you spend a penny on it.
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When it comes to 400 blocks I have sen alot of guys spend good money on bad.
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I made an error in the measurement, block is under 4 3/16, block is 030 over. Thanks for the advice. I'll have it sonic tested or resell and save for a stronger block. Thanks
1968 Malibu Sport Coupe, 489c.i. 590hp 600tq, TCI 200r4 Freakshow 3,600 stall, 3.73 12 bolt posi
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someone I know has one from a '70 ambulance with 4 bolt mains, its now a 406 in a 68 mali with a 5 spd, he says it doesn't ever go over 185 here in Fl., but he does know what he's doing when it comes to motors, I've heard over heat issues but I don't know first hand, never had one, the one your looking at a 2 or 4 bolt block?, I think if its a 4 its a steal :beers:
I have a 406 sbc with Dart aluminum heads. As long as the heads are drilled for proper coolant flow, and the motor's not bored more than .030, they're fine. Mine runs 160 degrees on the road until I get stuck in traffic on a hot summer day, then it may reach 190-200. I'm probably going to put a higher t-stat in it to let it run warmer down the road. It's got a B-Cool rad w/ dual elec. fans, no A/C.
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