I know the 2-main blocks are supposed to be better (stronger) then the 4-mains that were made. But how about the new ones? are they still the same or are new 4-main 400 blocks stronger ??

Just thaught about this question looking at this page...
http://www.goautocenter.com/400_small_blk.htm

 

Actually, the stock 4-bolt 400's were pretty strong. People get the idea that the 2-bolt was the choice block because it is stronger. The 2-bolt became the choice block because it allowed you to convert to a splayed 4-bolt main. Some may argue that the internal webbing on the 2-bolt is stronger, but I know for a fact that the stock four bolt has been able to handle 900HP and 9 second passes.
The block you are referring to on that website is CNC Sportsman block that GM recently introduced. All around it is a better block. It sells for a pretty hefty price though, but if you got the money, go for it.

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N/A 406, TPIS Miniram, 58mm TB, 30lbs injectors, Custom Ground Elgin Cam, Ported TFS heads, SLP 1-3/4", & DFI computer.
11.70@117mph

 

Please send me an email. I would like to talk to you about your 400. I have one in my 89 and haven't had much luck getting it to run correctly.

golfn103@hotmail.com

Thx!

 

Scott,

Another great source for 400 SBC info is here on this page in the form of Mr. RB83L69.

Cat knows his business....and is currently running a 400.

BOR

 

For what it's worth, World is coming out with what they're calling their Motown block, which they claim fixes all of the old production 400 block problems and sells for about $1000 less than the GM CNC block.

 

Thanks for the intro BOR! That's more than I will claim myself, except for the fact that I do run a 400 in my 83, and have for about 10 years now. Mine's a 74 2-bolt block.

But anyway... as far as the only 2 casting numbers that existed until recently, the original 400s were all 4-bolt. Starting in 73 they changed to a differnet casting, and all of those are 2-bolt. There were some reliability and quality control problems with the original 4-bolt ones; I don't have any way of knowing, but I suspect that when they redesigned the casting, they simply decided that they didnt need the other 2 bolts. However, the 2-bolt block (73 up) has more metal around the webbing area where the bolts go; so you come out with a stronger product by using the 2-bolt block and installing 4-bolt caps in it. The best of all worlds is using 4-bolt splayed caps.

What's your goal? Like Fast Life said, an old stock block will handle just about anything a typical street guy can throw at it; that kind of money would be better spent elsewhere in terms of getting bang for your bucks.

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"So many Mustangs, so little time..."
ICON Motorsports

[This message has been edited by RB83L69 (edited February 02, 2001).]

 

I know the price is hefty and wouldn't be able to get it but I was just wondering about the strenght of the block...
The thing is that I invested a lot of money last year in a newly rebuild 350 that blew up on me after about a month (because of a cracked block that the shop didn't notice, i know it's not hte 350's fault)and the car hasn't run since ($$) I kinda have the money saved up know and am looking into a reliable motor while also getting the most out of it.

 

I know the price is hefty and wouldn't be able to get it but I was just wondering about the strenght of the block...
The thing is that I invested a lot of money last year in a newly rebuild 350 that blew up on me after about a month (because of a cracked block that the shop didn't notice, i know it's not hte 350's fault)and the car hasn't run since ($$) I kinda have the money saved up know and am looking into a reliable motor while also getting the most out of it.

 

As long as you're just building a street engine, and not an all out drag car producing above and beyond 500 hp, either two bolt or four bolt should hold up just fine. The one suggestion I have for the bottom end would be a set of ARP rod bolts for a little extra insurance. I had a 72 two bolt 400 in one of my cars a while back, and didn't have any problems with the bottom end. Unfortunately, it fell victim to a piston coming apart at the wrist pin. It was making noises for about 6 months before it finally blew up. That's too bad what happened to your 350. Just make sure to have your 400 block checked over really good by a reputable machine shop.

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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."