WorK

im looking to build a 400 SBC. wanting around 500hp out of it. i hear that some of them come with stock forged cranks. my question is, what block's are the best (codes would be preferable) and what cranks are the best. need more info, ask and you shall recieve

slow95z

iTrader: (33)

buy a new forged crank and any block will be ok. i prefer the 2 bolt block with billet splayed mains installed for superior strength.

ZONES89RS

iTrader: (25)

From what i have seen, there was never a factory 400 forged crank, though i could be wrong.

kenSS

iTrader: (1)

go with a 2 bolt if possible, a scat cast crank will be fine 500 hp.

MrOverkill

iTrader: (1)

+1 A 2 bolt 400 block studded will be fine unless you want to spin it over 7000rpm, a set of splayed caps is not really needed at that power level and below 7000rpm. Also you will be fine with a cast crank at that level as well no problem assuming you wont be leaving on a transbrake everyday.....

Make sure you pin the blocks steam holes which ever way you go, they tend split around them and cause issues......

WorK

i can get a 509 cast number block and stock crank for $125. you think the stock crank is good to 500hp? or should i go aftermarket cast. i plan on revving to around 6500. and no transbrake, she'll be a 5 speed

kenSS

iTrader: (1)

i would still go with a scat cast crank. cheap and alot stronger than a stock one. just don't do to many 4000rpm clutch dumps or anything. if so then go forged.

bigfatls6

iTrader: (34)

The 509 is one of the best 400 blocks to use because of the high nickel content and is probably the strongest of the stock 400 blocks. Becareful when you buy it check the boresize on it and make sure you will not have to bore any larger than 30 thousandths over stock bore. The cyclinder walls are very thin on the 400 blocks. You should also spend the money to have it sonic tested. One of the main things you need to look for when looking at used 400 blocks is that they crack through the lifter valley. Make sure you check it good and measure the bore on the cyclinders before you buy it.
I think you will be ok with the stock crank to 500 hp but not much morethan that. But then again the stock 400 block probably wont hold much more power than that unless you fill the water jackets with block filler. I would probably use a descent rod though if I were you. find you a good quality forged I beam rod. The h beam rods would probably be a little bit of an over kill and will be heavy and harder on you stock crank. If you plan on a naturlay asperated motor go with a 6 inch rod and for a nitrous motor go with the 5.7 rod.

WorK

the 400 i found is a stock pullout. untouched, pulled out two weeks ago, still running.

not sure what i'll do about the crank. i'll probably do the scat one. as for rods and pistons, i found some speedpro 11:1 compression forged pistons that use 5.7" rods, i figure the scat I-beams (good for 750 horse) will be good. it will be an all motor car... at least at first. i want to build it for a small shot in case i get curious

NovaCain383

iTrader: (8)

https://ls1tech.com/forums/non-lsx-parts-sale/1007168-parts-f-s-f-t-crower-brodix-eagle-holley.html

Check out this link. I have a good bit of stuff for a 400 I am trying to sell. I just might have what you are looking for. Let me know if interested.

Also look at mortec.com They have all the casting numbers listed for GM stuff. So you can check the numbers on all the stuff you look at buying. Hope it helps you out.

sixt9er

iTrader: (2)

I had built a 517hp, (dyno'd) 406 cid Chevy. I used a 2-bolt block, Scat cast crank, Scat 5.7" 4130 I-beam rods, Speed-Pro H 616 CP pistons (.030 over), Dart Iron Eagle heads with 64 cc chambers (milled to 62cc) and 200 cc intake runners, a Doug Herbert custom roller cam and a GM Performance Parts "Bowtie" intake manifold. It had unbelievable torque in the mid range and nice power up to 6800 rpm.... my only regret is not using forged pistons and using splayed main caps in the engine...I used a "509" block from 1972.
If I were you, I would invest in a GOOD cooling system as 400 's tend to run a bit warmer than 350's and most other small blocks...good luck.

bowtiescottsdale

if it was a forged motor could you spray it, or is the block to weak?

MrOverkill

iTrader: (1)

Pin the steam holes and they are better but not great, I've owned and seen plenty of them fail in the area of the deck surface.

Best bet for over 600hp or 7000rpm is an aftermarket block, I've mad more power than that with them years ago but a good block is much cheaper than they were in those days. I have a Dart blocked 406 that makes over 800whp and I have no worries, I would be SOOOO nervous if it was a production block at 200hp less than that.....