400 sbc ?'s

PittSpeed Automotive
1

looking for some 400 info and maybe general chevy answers.

1 is the 400 a 6.6 liter?
2 ive read they had cooling issues. what are they?
3 what did chevy call the engine ( for example ls1/lt1) if anything at all.
4 i read if you put a 350 crank in a 400 block it will be destroked to a 377 . do you still use all of the other stock 400 parts and just bolt the 350 crank to the 400 rods and pistons and cam and run it? or do you have to change more than just the crank?

that should do it for now.

2

Can answer #2…the steam holes that are between the cylinders were troublesome and some had overheating problems.
#4… must use 350 crank with main bearing spacers, 350 [5.7] rods with special order pistons…however I know that keith black 377 pistons are the same # as 400’s…top end of your choice.
In the “old days” we threw many 400’s away because we considered them junk…however we didn’t have the choice of aftermarket parts we have today.

3

1 yes
2thin cyl walls will over heat to much in a 3rd gen f-body!
3 gen1 small block
4 yes ,it we be a 383,cam what ever u choose

4

Pewter, check #4

5

350 crank makes 377

if i remember correctly the earlier ones had 2 freeze plugs. which are the ones to search for. most times they are easily identified with 3 freeze plugs per side of block.

with thin cylinder walls makes them prone to run hot.

what are your plans with 400 SBC?

6

i’ve heard all the overheating stories, but have yet to actually see or meet someone who actually had it happen, also heard it is not really a problem until you start boring more than 30 over

the 350 crank in a 400 block shifts the power upward in the powerband alittle. and i’m 99.9% sure both the 350 with a 400 crank, and a 400 with a 350 crank using stock bores are both 377’s. 30 over bore makes 383’s. i have no idea about the which pistons or rods to use. but my guess would be 350 rods and 400 pistons

7

Stock 400 block with 350 crank is a 372. 30 over gives you a 377.

A 400 in a heavy pickup or towing would always run on the hot side…Just the nature of the beast

8

Wasn’t this where GM dumped most of the 400’s?

9

correct…you would find a few in implalas and caprices

10

Thats what I was thinking but wasn’t sure.

11

its been a long time ,brain fart:hsugh:

12

low temp thermostat, a good radiator, and good electric dual fans will keep it cool.

i havent heard of many overheating problems if those are taken care of. aftermarket heads need steam holes drilled into them to run on 400sbc

13

haha youngin!

14

just do a 406. find a good 400 crank or get the current one cut, bore it 30 over and run it. get a set of ls1 fans from brian. and i think you should be running the lower spoiler piece too brian should know what i mean.

15

i got the kit to rebuild the 400 already and i have the spoiler piece too . i just need a few more things and its going in. the other 400 block we got off you is running already and in a 98 s-10.

16

My vote, 406 all the way! A half fill of block hardner, longer con rods, good heads and a big cam NICE!

Best 400 block casting number ends with 509…Hi Nickle block

A buddy of mine ran one in his Chevelle destroked to 377, ran GREAT! GM off road mechanical cam, worked camel backs. What a ride!

I remember there being issues with the thick bearings…always use the spacers and 350 bearings if you’re gonna do this.

17

runs good? what cam and heads did he use and did he overbore it?

18

I’ll second half fill the block!

19

Destroked 377’s make damn good motors. they can rev quickly with that short stroke, and make good power with big bore. can take advantage of more airflow from bigger heads.

but if i had a 400 block, i’d bore it out some and make it a 412-415. thats my dream motor…a Motown 415 with a small turbo on it or a procharger.

20

30 over, running 202 heads with 3 angle valve job, cant rebember the cam specs, decent idle, edelbrock intake and carb, msd ignition, turbo 350 (now blown). Turned out to be a pretty strong runner…