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406 ss monte 06-12-2004 01:31 PM

looking for a good after market 400 sbc block
i went to the machine shop yesterday to get my bottom end balanced, & before i left he told me that sence i'm going to shoot a 250 shot of nitrous on it, it wouldn't last long. he said the main webbing would come out of it. so i'm looking for a good affordable after market block. what i want is every thing in it's stock location, & the big 400 mains.

the dart lil m block would be great if i could afford it, so would a motown, but i don't have $2,000 to put in a block. i even asked about a 400 2 bolt main with splayed main caps, he said it would still bust out the webbing, just take it longer to do it. if i would have known this, i would have built a 383, just for the fact that the 350 block is stronger.

by the way, this is for a street car.:evil: i'm pushing a little over 500 hp out of it, & with the n2o it would be 700-775 hp. :pain:

please tell me where i can get a affordable block. the bore is 4.155"


DoubleVision 06-12-2004 01:39 PM

we sprayed 350 horses to a 400 small block with a stock bottom end for a whole season and didn`t have any bottom end problems. set your bottom end up with studs and I doubt you`ll have any problems out of it, providing your Nitrous is set up properly and your running forged pistons and good rods. keep control over the RPM`s also. If I still didn`t feel safe in your case I would just get a "progressive" nitrous system to help soften the blow.

68c10owner 06-12-2004 01:43 PM

my friend was running a 410 sbc with a stock 2 bolt block with a scat lower end with nos and it was a low 9 second car. i don`t know what shot he was running but it only ran low 11`s on the motor alone so i`m guessing he had more than a 250 shot. he raced it for a long time with no problems at all. a 2 bolt with splayed main caps should be fine. i`m not a big fan a nos but i think your crank and rods would go before the main webbing. i would not use a stock 4 bolt 400 block though. i would check with another shop for a second opinion. i`m not saying your guy is wrong or doesn`t know what he`s talking about, i`m just saying i`ve seen it done and the motor was ran hard.

trees 06-12-2004 07:37 PM

I know a guy building circle track motors putting out 680HP and they are holding up good. He uses the high nickel 2 bolt main blocks and splays the other two bolts (studs) I have not heard him addressing any cracked webbing, but the high rpm circle track motor may not be experiencing as high a stress as the sprayed drag motor. I would get a few more race engine builders opinion before blowing of your block.


406 ss monte 06-13-2004 08:54 AM

whats the casting number of the high nickel block? i think it's 511, but not sure. their two bolt mains as well i believe. please correct me if i'm wrong.

i can get a dart aluminum block, all 5 mains are 4 bolt's. the oil pan rails are spread .800", & it takes big block cam journals, & i would have to run a remote oil filter. i can get it for $ 1,000 bucks. the only thing is, i've been told a oil pan to wet sump the block will cost $600 bucks. plus i can't find one that will fit my 85 ss monte carlo, in fact i haven't found any yet.

what to do, what to do.

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