400 sb

[70 Bowtie]

Hey all, I need some clarification here! When I took the 250 6 cyl out of my 70 step, and put in a 1971 400 4 bolt, alot of my friends said that the 400 is not the best choice of engines!! They say thier is alot of issues with over heating? Is this true? The motor runs great!!!

Brett

[Tynee]

I'm not a 400sb expert. All I know is what I've been told: light wieght, big cubes. I would think you wouldn't have any more trouble cooling that than you would a 396BB or something similar. It seems like if you did start having problems, you could upgrade to the 4 core radiator and make sure the rest of your cooling system is in top-notch shape and be fine.

[Scrubby]

I had a 400sb in a 77 suburban. That thing was great! I never had any issues with overheating. I think the overheating rumor started with people slapping on aftermarket heads and not drilling the steam ports.

[jimv]

I have had several 400 engines and never had a problem with overheating. Should be fine as long as you have a good radiator and electric fan. I have a 400 sitting on a stand ready to put in my 71.

[Novaguy73]

The 400 SBC are notorious for overheating. I wont get into the details but it has to do with siamesed cylinders. Anyhow if you are going to install it, make sure you have a good radiator and waterpump. I would suggest a cheap aluminum radiator. Keep your temps low and you should be fine.

[Bowtie67]

The only 400's that where notorious for over heating where those guys that where cheaping it all out by using old radiators that they kept putting pepper & stop leak in to plug the holes. All this did was restrict water flow, you need to have a good radiator, prefferably a 4 core radiator, that 6cyl radiator you have will not work. If heads have been replaced there needs to be a steam holes in the heads, that doesn't mean you have to go out and specifically locate 400 heads, 350's head will work, they just need to have the steam holes drilled in them. Most machine shops will do this, the last set I had done cost me $25, you can also do them yourself if you feel confident in doing it, I have also done it in the past but breaking drill bits in the head are a real pain to get out and if you drill wrong you may end up having to find another set of heads, let the machine shop be responsable..

[russellmarling]

Just make sure that you have steam holes in the heads and a four core radiator and you will be fine. I put one in my '83 Camaro and I loved it! With an 180 degree thermostat it NEVER got above 200 in the summer with the AC on. I loaned the car to my sister and she totaled it, so I had to sell the car for parts. I really miss that car and the 400.

[wolfthing2000]

The thing that seems to be missunderstood here is not that the engine will overheat because it is a 400, it is because it is a 400 it will most not likely survive a situation where it overheats!!!!!

Also that litlle mention of "siamesed" cylinder walls should be a big tip off also::::::::::::::::::::: best explained as so::

imagine an iron cylinder setting there on the table in front of you and there is a cooling jacket around it, but only part of the way around the cylinder. Now light up your torch and heat up the inside of that cylinder for a few minutes. Turn off the torch and measure it with a mike or bore gage and see how round it isn't!!!
There is the problem. Higher oil consumption in less miles on the odometer. Proven in fleet use!!!
Also, you might ask yourself , what did Chevy do with the idea for the 400 SB?????

But I guess if you do have one you will insist that I am wrong ( purely in denial) and say it's the best thing ever from Chevy.

The truth is that measurements and the laws of physics prevail here.










I am running for cover from the rocks that will soon rain in on me!!!!

[409biscayne]

I'm no expert on 400sb , but i know the drag racers in this area look for the 2 bolt blocks , the're supposedly stronger than the factory 4 bolt . Then they add aftermarket splayed 4 bolt caps , like Milodon . At least in their opinion.

[ed455]

Originally Posted by wolfthing2000

imagine an iron cylinder setting there on the table in front of you and there is a cooling jacket around it, but only part of the way around the cylinder. Now light up your torch and heat up the inside of that cylinder for a few minutes. Turn off the torch and measure it with a mike or bore gage and see how round it isn't!!!
There is the problem. Higher oil consumption in less miles on the odometer. Proven in fleet use!!!
Also, you might ask yourself , what did Chevy do with the idea for the 400 SB?????

But I guess if you do have one you will insist that I am wrong ( purely in denial) and say it's the best thing ever from Chevy.

The truth is that measurements and the laws of physics prevail here.










I am running for cover from the rocks that will soon rain in on me!!!!

Here we go again. He had a cracked one, and now they're all bad.

Yeah, they're all bad. I take as many of them as you want to get rid of.

[wibilly]

imo they can't be beat for low rpm tourque i never had a overheating problem with one.the bigest problem i've seen is in high rpm applications. because of the long stroke they will egg shape cylinder bores but if used for street use and not over reved can't be beat. i to will take all i can get my hands on

[72armyswbtruck]

Are you talking about the chevy small block 400 or the big block 400? Are your heads wide or are they tall?

[70 Bowtie]

Thanks for all the replies. I see we have several opinions! All I know is the motor is a 1971 chevy sb with a fresh rebuild, I did put a larger radiator for better cooling. Other than the 2 1/2 pipes and flowmasters, she is pretty much stock (for now)

Thanks again for all your help

Brett

[ChevLoRay]

I had a '76 Blazer 4WD, with a 400/350TH combo. I pulled a 25-ft travel trailer with it. It had A/C, so the big radiator came with it. It didn't matter where I went, it worked just fine. This was in '83-85, so you know it wasn't a new vehicle.

As for the siamesed cylinders, Chevy did do that, but installed the steam vents in the blocks to address the issue. There was some controversy when they were new, but I have never heard of anyone having an issue with one, specifically because it was a 400SB.

There have been many of them punched out to 406 cubic inches, and more with stroker cranks.

It doesn't matter which engine you use, if you miss treat it, and fail to maintain it, it will fail you. Some people may have been able to skirt the issues over time, but eventually it will fail. Take care of the engines you have and they will take care of you.

[Buckman]

I have a 406 in my 69 z28 camaro with 500 hp and have nothing but fun.

[CHEVYE]

There's nothing at all wrong with a 400sb when it's built right, treated right, and you understand what the differences are between it and a normal small block.

Back when I raced I was helping a neighbor build a 400 and the block cracked in between one of the threaded areas for a head bolt and the cylinder wall. He was torquing all of the head bolts and one of them kept spinning and lwouldn't tighten. He got the block sleeved and o-ringed and didn't have problems afterward.

I seen one let go in the bottom end. It was a 4 bolt and it cracked between 2 of the main bolts. The engine looked like a bomb went of in it . The crank and cam broke in a few places and it popped a hole in a cylinder wall big enough to put your fist in . I think this is why alot of guys prefer a 2 bolt with splayed caps.

If yours is pretty much stock I wouldn't worry about it. Like mentioned above, I think they get a bad name from people messing with them and not understanding them.

[dubya]

I run my 400sb w/th350. I have a 190 degree thermostat, and a big 4-core radiator. It kicks butt and is rock steady on 190. One time I thought it went above 190, in 115 degree weather, but I was on a side hill, trying to give my girl a kiss... when she she spilled her beer.

It never moves off 190. I wheel, pull, go hunt'n/fish'n, ski, boat, camp and everything in/with the truck, and it stays cool.
W

[wolfthing2000]

BEWARE the "400"!!!!

So if my block cracked, so what. I had the rest of the parts to build and could have picked up a good 400 block for 100 bucks.


I researched it and did the math. The egg shaped bores and the cracking are a problem and always will be! I steered clear!!!
The facts don't lie!!!!
NO GETTIN AROUND IT NO MATTER WHAT!!!!!!!!!!!!!!!!

[ed455]

Blah, blah blah. Keep preachin' wolf, at least you've convinced yourself.

[wolfthing2000]

Blah! Blah! Blah! Here we go again.








2+2=4,2+3=5 siamese= out of round=NaNaNanna na na!!!!!!


I win!!!!!!!

[CHEVYE]

Ya'll are both right.........in a way.

This is getting good.

Where's the damn popcorn eating smiley that other boards have, I sure would push it right now.

[LUV2XCLR8]

Play nice fellows or 70 Bowtie's thread will get closed

[Liz]

Originally Posted by wolfthing2000

Blah! Blah! Blah! Here we go again.








2+2=4,2+3=5 siamese= out of round=NaNaNanna na na!!!!!!


I win!!!!!!!

ya'll cut the sh!t already.......the bs gets old fast........ play nice, post right or don't let the door hit you in the ass..

[wolfthing2000]

There shouldn't be a problem with getting the thread closed. It did last time when some OTHER members started violating the rules.!!!!

There is a lot of scientific info out there about the 400 and it's drawbacks but none of that applys to the 350. ( Not " siamessed up")

After all, Chevrolet had the good scence to dump the 400 idea!!



Ya can't argue against those facts!!!!!!!!!!!!!!!!!!!

[Liz]

bye...........