MONGO510 Posted June 2, 2006 Share Posted June 2, 2006 Hey fella's, I did a search and got nothing. What is the most desirable 400 block to use in a medium heat street engine? Quote Link to comment Share on other sites More sharing options...
jt1 Posted June 2, 2006 Share Posted June 2, 2006 There's essentially no difference. The variations between individual blocks will be more that the difference between different casting #'s. A four bolt is stronger than a 2 bolt, but the best is to take a 2 bolt block and put 4 bolt splayed caps on it, since the 2 bolt block itself is a little stronger than the 4 bolt block. Before you spend any money on a block, get it sonic tested to see what you got to work with. My most recent hand grenade had walls as thin as 0.035", a complete POS, and it never really performed to suit me. John Quote Link to comment Share on other sites More sharing options...
280zwitha383 Posted June 2, 2006 Share Posted June 2, 2006 I'll have to disagree with you JT1, I'm close aquaintances (haha) with the owner of the most reputable machine shop in this area. He said to stay away from certain 400 blocks and I couldn't tell you which ones they are. He says that anytime people bring in those certain blocks he will tell them not to put any money into it and that the few people that have gone ahead have come back with major failures. If noone else chimes in maybe I'll give him a call and see which casting #'s he says to stay away from. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 2, 2006 Author Share Posted June 2, 2006 Well, I bought this engine on ebay and I already know where the weak point is in this block, as it was race prepped, made 10 passes, and cracked a cylinder wall. It is at .030 and has like new bores. It is a 509 block. I thought maybe I would have it sonic tested and sleeve the bad bore if the other bores checked out. It has a new rotating assembly and is setup as a 327/400 crank/block. Same basic long rod engine that Grumpyvette posted. What do you think? John Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted June 3, 2006 Share Posted June 3, 2006 The 509 is the one you want, early model 2 bolt block. The 511 is the 4 bolt block, also desireable, the 817 is the late model 2 bolt block. My understanding from a buddy that worked at the GM foundry for new prototype motors, Joe Rakov, said way back when that the 509 and the 511 is the same mold, which is why I guess alot of people put 4 bolt caps on the 509 blocks. He said that the 817 was later, is alittle lighter, like 10lb mostly from the web area and is not the high nickel content. Could all be wrong, but that's what I've heard. Consequently I've seen performance motors built using all three blocks successfully so what was said befor about sonic testing is worth the nickel it costs. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted June 3, 2006 Share Posted June 3, 2006 I've built quite a few 400 based engines. The 509 block IS the best block. It has CONSIDERABLY more material along the main webbing and pan rail than an 817. On a 400 based block the index of the main caps is as large as a regular 4 bolt SBC whether or not it has 4 bolts, the 4 bolts actually take material out of the main webbing and weaken it. I don't have any bare blocks laying around at the moment or I would post pics of the wbbing differences. The 511 is not quite the same as the 509 but does have more meat than the 817. That said, I've built some 817 blocks that were abused I would not sleeve a 400 block for performance use. IF you do decide to do so be aware that the adjacent cylinders must be bored because the siamese cylinder configuration, and the press fit of the sleeve will distort neighboring bores out of round (alot). As much of a fan as I am of low budget/ OEM parts builds, this is one place where the money invested in an aftermarket block is worth it. The average price of a guaranteed 400 SBC core block now that will machine to .040" or less is ~$200-up, usually around $300. Figure $250 for a block, $80 decking, $125 for bore and torque plate hone, $50 clean, $80 sonic test, $50 R&R cam bearings and block plugs, $100 for block-fill and labor, plus labor and parts to plug deck holes (should be done to firm up deck), align hone if needed ($70-100), etc.. That's about $900 pretty quick, and it will never have as good of ring seal as a Dart (preferred) or World block. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 3, 2006 Author Share Posted June 3, 2006 How much work do you have to put into a dart or world block before it is ready for assembly? Also,this is to be a street motor . John Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted June 3, 2006 Share Posted June 3, 2006 Well, they come ready for final honing for about 1800 for the dart little M with 4 bolt nodular caps, good to 1200+HP! If you want, you can get a race prepped CNC block for about $2300 I think. You have to add about $150 for the billet caps, good for 2000HP or some insane amount of HP anyway. The deck height is standard 9.025 so if you want less than that you'll have to have it decked. Also made, I think (World) is the tall deck, 9.325 deck height, good for the 454 cubic inch and 470+inch small block. You can also get raised (.391) cam location which is a great help when building strokers. You don't usually have a problem with rod/cam interference unless durations get over 250 with a roller cam, but in most cases a small base circle (.900 or less) is required to get rod/cam clearance. Typically most hipo engines have a deck height of about 9 to 9.005 in order to achieve .040 to .045 quench, which is desired IMO. You have to ponder the idea of having a standard bore, the ability to bore it .020, .030, .040, .060 and more all the way to 4.200 inches. So, unless you window the block, it'll last a long, long time, and be durable enough to handle all kinds of HP. So, in theory, you can start with a 350 and end up with a 380+ cubic inch motor in the end after a couple hundred thousand miles of fun. That or stroke it and get lots of cubes right off the bat. If you've ever thought of it, build a big inch motor with 9:1 compression and watch the smile that develops on your face everytime you start it up. It always comes down to $$$, but if your intended plans don't call for more than 600HP or so, then I'd go with a stock block, otherwise I'd go dart. I can take pictures of a stock block blown alky 350 that ran in a southwest supercharger series rail dragster, 6.90 at 202mph so it's not that the stock block can't take it, it's just that it takes alot of precision machine work to get it right and that's what makes the aftermarket blocks so appealing IMO, especially for the novice builder that doesn't know all the tricks to get the stock block to that point or has a machine shop with the knowledge and equipment and experience to do it either. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted June 3, 2006 Share Posted June 3, 2006 The problem here is he has purchased a block that already has a cracked cylinder. Not a good idea to sleeve a 400 for reasons I mentioned. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 3, 2006 Author Share Posted June 3, 2006 Dang, someday I will learn that when ever I try to save a few bucks, I end up taking a bath. Well, I guess I ended up with a good crank, rods,forged pistons, 202 aluminum heads,Arp head and main studs,and a complete howards roller setup(cam,rollers,1.6 rockers,pushrods,springs and titanium retainers). If I buy a dart block should I transfer the ARP main studs to the new block or are the supplied bolts stronger? Quote Link to comment Share on other sites More sharing options...
dr_hunt Posted June 4, 2006 Share Posted June 4, 2006 They come ready to go on the bottom end, the head studs is what you'll need though. The dart block can use a longer block thread length head stud, but it's not mandatory, you can use what you already have. Nice thing about aftermarket blocks, blind head bolt holes, so no more leaky head studs!!!!! It's the old cheap route that ended up costing more money than I thought. Normal, I think most of us have done that. Chaulk it up to "learning". If it cracked a cylinder then it seems logical to think that they were too thin in the first place, happens every now and then. Either get another good block or go aftermarket. What oversize are the pistons? Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 4, 2006 Author Share Posted June 4, 2006 The pistons are Forged .030 flat tops and are in as new condition. Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted June 4, 2006 Share Posted June 4, 2006 I would shop for a different OEM block. You asked about a medium heat street engine, so I'm guessing a sub 6500 rpm N/A platform, probably around 450 HP? If so any of the blocks will work for you. Even the "weak" 817. Have it thoroughly checked, and for machining I would have it line honed as needed, decked, bored and honed with torque plates (absolutely necessary on a 400), and otherwise nothing fancy. You could have a partial fill done about halfway to the water pump holes to make the cylinders more rigid. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 5, 2006 Author Share Posted June 5, 2006 What do you consider the maximum bore on a stock 400 block? minimum wall thickness? Quote Link to comment Share on other sites More sharing options...
jakeshoe Posted June 5, 2006 Share Posted June 5, 2006 I LIKE to stay at less than .040" overbore, and in your case, you need to find a STD block to salvage your pistons. I have run them at .060" and IMO the cyl wall thickness isn't the problem at .060" it's the head gasket sealing on a stock block. .180" cylinder wall thickness minimum on the thrust side. Quote Link to comment Share on other sites More sharing options...
MONGO510 Posted June 7, 2006 Author Share Posted June 7, 2006 Thanks guys, yous the best! Quote Link to comment Share on other sites More sharing options...
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