GM 400 sb casting help

[cj422]

i was wondering what is the difference in the casting of a GM 400 block other then 2 or 4 bolt. like the 509, 511, 817 my block is the 817 that now has eagle splayed main caps. thanks CJ :?

[stevehgs]

Stay away from the 4 bolt blocks with 3 freeze plugs on each side. They are the weakest of the bunch..

[Robert1320]

the stock 400 block are thin and weak.
I just stay away from them if you are making power.

[cj422]

thanks for the info guys, mine is a 2 bolt with 2 freeze plugs. heres the bad part about mine. I just put eagle mains and align bore, moroso filler up to the freeze plug, clearance for 3.875, bored .040, decked .015. i have 7 350 blocks and my 383 thats on here for sale. i think ill build the 383 and sell the 400. again thanks guys you saved me a lot of money that was going in to it. Cj

[Robert1320]

What are you trying to build and how hp are you wanting?

[Robert1320]

CJ you have PM.

[bjuice]

just like the man said above...what are you wanting to build with this 400..i agree with the rest of the guys that the 4 bolt (3) freeze plug 400 is the weakest (webbing etc)....However i have seen these blocks handle 600 hp ..NO PROBLEMS !!!...i have owned several of these blocks and ran the DOG SNOT out of them....turning 7200 rpm......NO I WOULD NOT try to make it some high hp spray or blower motor...but i would not hesistat to run 600-650 ponies with this block....

If you have blocked filled that (2) freeze plug 400 block of yours..i would not hestitate to run it and go over 700 hp with it..i personally think you would have a better drag motor than the 350 block......my opinion only...

Brian

[cj422]

hey bjuice thanks for the info. i can put a pic on here but i dont know how to resize it. but can email one. my filler in the 400 is up to the bottom of the freeze plug. (front plug, motor mount) the machine work is great and was cnc. i like how they install the splayed Eagle caps. i did remove my 383 ad but posted one of the other 350 blocks ad# 936481. i am keeping it nat. aspirated. i was going to build it for drag racing only, but i like the pro-street better even if its only a weekend runner. as a truck driver i dont get much time to go to the track. except right now i have a little time off. i want to build a killer street engine and have some fun :D thanks cj

[bjuice]

then in my Head..you just Validated using the 400 block...if your going PRO-STREET....the only problem you might have and this is a MIGHT ONLY,,is cooling the motor...if you only filled to bottom of freeze plugs you are probably ok...top of the water pump holes and its too much for circulating water on the street use...whom-ever filled your block knew these blocks were weak in the webbing......so if the machine work is done i would rock-and-roll with it.....the extra CI never hurt anyone..also the 400's (406) will give you the extra TQ the 350,355,383 will not give..


for the record my wife has a 406 in her 69 camaro..2 freeze plugs 4 bolt..and it made close to 500 hp on the dyno....in a 3300lb car, all street trim, DOT ET Streets 26x10's, thru the mufflers, footbraking, with a standard choke horn holley 750 carb,...the car runs 7.40's all day long in the 1/8...whats this..11.0's or high 10.90's in the QTR ??????...and she drives it !!!!.... 8) 8) 8)

Brian

[cj422]

i didnt think to much about over heating thanks for pointing that out. my block was machined on a RMC model V30 machine by www.backwoodsracing.com of Midland,MI they were busy at the time and it took 1 month before i got 2 of my blocks back. and am very happy with there work thus far. he did tell me they were weaker and he recommended the Moroso filler. but this is the first time i had used it and i dont know that much about it and the strenght of the block. plus the clearancing has got to be close to the water jacket if there was no filler. i plan on building a 422 and like i was telling Robert1320 if i can get around 500 to 550 with out going to power adders then that would be great and i would be happy. wow thats got to be a sweet 69 you have. and to have a wife that can drive heck out it. 8) 8) i was watching the junior dragsters saturday and im like wow i just got beat in the 1/8 by a 12 year old :oops: 8) lots of fun though. i have a lot of work to do on my truck and hope to have it done by the end of winter next year. :) CJ

[blown375]

Don't be to scared of that 2 bolt 400 block. I ran them in bracket cars and nitrous street cars for years with no problems the last one I had was a studed 2 bolt block with splayed caps ,filled to the freeze plugs . That motor was .040 over with a reworked stock 400 crank, aluminum rods ,14-1 ross pistons .227 afr heads, and a 2 5/16 hilborn stack injector on alcohol .
I ran 8.0 @160 with that motor in my 235" dragster and that motor went to 8600rpm on the burnout every pass with no problems to the block or crank.

[Robert1320]

CJ,

Your goal are reasonable. The 400 will be ok.
Much of the stuff I build is for guys wanting much more!

Enjoy the ride and have fun. Invest in the cooling system like Brian suggested sometimes a 400 is a little tough to cool. Make sure you heads have steam holes it will help a street driven car stay cooler.

[cj422]

I want to thank everyone for your time and expert help, great bunch of guys thanks Cj

[hink]

We machine a lot of blocks in our HAAS 4 Axis machining center and we have seen many problems with the 400 blocks with there thin decks thin webbing and with the big main line and big cylinders makes the webbing weaker the the 350 block and the bigger bores make for a weaker deck then the 350 block as well.

We have gotten far more emails and calls with problems with the 400 blocks.

Any block that comes through our shop is sonic tested and we have seen a few 400 blocks that were not safe for a high horse power application and we have a virgin 400 block that is cracked from the cam tunnel down to the mains.

Don't get me wrong we have machined a few 400 blocks and some have worked out well and some have failed or have developed cracks after a season of running.

[bigg]

you want the 509 casted block is the best...dont buy all the hype about the 400 blocks., they will work fine if properly prepared..ive ran them for years with no failures due to the block