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400 small block

Beastk577

Beastk577

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Location
Norfolk, Virginia
I own a 77 K5, I found the original option plate, says it came with a 400 small block, and an M40 Hydramatic. At some point that must have died, as one of the previous owners yanked it and dropped in a 350. I don't care about the transmission, but I would like to get another 400 to drop in. Anyone know where I can pick one up? I've check the local bone yards, no dice.
 
Better off keeping the 350, 400's are known for overheat issues and cracking the block lengthwise in the lifter valley area. I'd guess that 9 out of 10 400 blocks that customers brought me to rebuild were cracked as I said.
 
You could try advanced auto for a reman 400 motor. The motor in my blazer is a 408 which came from advanced auto and I just redid the motor since the previous owner was by no means was a mechanic
 
I am kinda shocked, they are all over the junk yards here. As previously mentioned, they have kind of a bad rep for over heating... siamese bore, blah, blah, blah.
 
4X4HIGH said:
Better off keeping the 350, 400's are known for overheat issues and cracking the block lengthwise in the lifter valley area. I'd guess that 9 out of 10 400 blocks that customers brought me to rebuild were cracked as I said.
Click to expand...
This.
4x4high is the resident engine guy. Sure he's thrown out more 400s than any of us have ran
 
I had a 400 SB in my '77 GMC K2500,,that I pulled out of a '78 K-10 Suburban...
It had just over 100K on it and ran great,bought the whole truck for 425 bucks,it was rotted from the door handles down,and had a flex plate with a bald spot...

Despite the bad reputation's 400 SB had for cracking,overheating,etc,I had no issues with that engine,and I did manage to overheat it several times with the plow blade on the truck,till I found out someone took the thermostat out--and I learned how to lock the fan clutch ..I fully expected to have at the least a head gasket fail,but it never did..

More than one 400 SB friends and relatives owned had issues with the cam bearings,the block evidently warped enough to make them mis-align,and they had to be line bored and oversized bearings installed..

While I liked the 400 SB as far as torque (seemed equal to or better than a '74 454 that it replaced,a smog era Chevelle engine),and the lighter weight,if I had to do it again I think I'd go with the BBC or a 350,just because of the potential problems a 400 was noted for..they also have some "400 only" parts like the externally balanced flex plates,head gaskets that fit a 400 only,no other small blocks...different rocker arm ratios...among other things..
 
I had 2 400 small blocks, one in my 77 Blazer, and one in my 77 K20. Both ran fine, never had an overheating problem or anything. But man, they both SUCKED with gas mileage. And the Blazer was converted to part time 4X4 too.

If it were me, I'd just stick with a 350.
 
I have one, but it was cheap.

Mines never had the odd sitting in traffic overheating issues that many claim. Maybe I got lucky.

I wouldn't go looking for one though.
 
The previous owner did you a favor. Most of us are not so lucky.

Martin
 
If John comes in here, disregard my statement above. Water heaters for the win.
 
Piece of shit. I was an idiot as a kid and pulled a perfectly fine stock gutless 350 and dropped in a "hot" 406. Didn't realize how true that statement was, that POS was constantly getting hot. It was like christmas morning when that hunk of junk finally spun a main and the nightmare was over. I did the world a favor and buried that paper weight somewhere in the back 40.
 
rjfguitar said:
Piece of shit. I was an idiot as a kid and pulled a perfectly fine stock gutless 350 and dropped in a "hot" 406. Didn't realize how true that statement was, that POS was constantly getting hot. It was like christmas morning when that hunk of junk finally spun a main and the nightmare was over. I did the world a favor and buried that paper weight somewhere in the back 40.
Click to expand...

That was an awesome post right there.
 
I always love it when guys bag on 400's. ...

Then they can't figure out how the hell my Dad and I make ' m work so f'ing well!

But you can't get great mileage out of one, even if you can bear driving it like an old lady!
 
My 78 had one.. Never had any problems with mine.. But my truck had a 4 row brass radiator too and kept the stock thermostat and clutch fan.. It also smoked many 350s.. Too bad I was dumb and rolled that truck..
 
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