1970 chevy k5 w/factory sbc 400?

[losangelesk5]

Hey, anyone ever heard of a blazer with a factory 400ci. I checked mine, the numbers on the block show 1970 4 bolt main. Is this a weird option or what? I"ve seen some 400 ci trucks but never a blazer, Any info?

[Blazer1970]

No. The 400 cid small block was not used in any trucks in the '67 - '72 era. Trucks with a 400 emblem had a 402 big block. No big block was available in a Blazer, ever.

[pound41]

No small block 400 in blazers. You will need to find the stamped number on the block with the vin part on it to tell if its original. My 69 RS/SS camaro has a block number that was originally listed for chevelles and Novas.
It was later learned that 6 were put in camaros. Through my camaro research and a book called Chevrolet by the numbers I learned that when vehicles came down the line if they didn't have a block or part because of shortage
They grabbed some comparable. Since your blazer is a 1970 first year they really pushed the blazer you never know

[RLONG]

They started putting sb400 in the trucks in 72 and maybe some 71s i do remember that but i think in 70 it would have been a 396 that was called 400bb

[71swb4x4]

I am with Blazer1970. No 400 small blocks in 67-72 trucks. I have never heard of it, and never seen a documented case.

Am I saying it's impossible that the factory did it? Well, a lot of things are possible. From what I have seen there hasn't been anything to make me believe that any small block 400's made it into the 67-72 trucks.

[pound41]

The probablity is not great but this is how a 400 block would have ended up in a blazer. They had small block 400 in monte carlos and chevelle etc in 1970 I owned a 70 monte with one. Blazer rolls down the line we are all out of 350 blocks what do we have on the line next to us small block 400 monte carlos grab one and stamp it. Which would be a true small block 400. Motor assembly area for Blazers. We are out of 350 Blocks. What are we going to do. Shut down the Blazer assembly line for a day while they cast more blocks
What do we have plenty of Small block 400. Put a 350 crank in it its now a 350 stamp it and get it out. I had a heart attack when I first checked the numbers on my matching number RS/SS. Checked Chiltons and other books all said Nova Chevelle 350. It wasn't until I got Chevrolet By The Numbers and found the info there. Which this was 12+yrs ago. The guy who did the book got to see all GM documents and he got to interview line workers who said when we ran out we grabbed what was next line and made it work. Again probably a swapped in 400 by a previous owner but you nevver know

[losangelesk5]

Yea thats what I figured, I guess I was hoping I had the Rarest Blazer in the world. Thanks for the info Everyone.

[72blue]

A SBC 400 has different main journal size than a 350. Could not have put a 350 crank in it with out welding it up to the 350 size and machining it down to specs.

[too much stuff]

Not aware of any 400 small blocks in these trucks, blazers or burbs until after 72.
Not so sure about the 6 engines put in camaros with different numbers either. I am not saying it didn't happen, but highly unlikely IMO.

[JMac11]

Relating a story I have told before......1967 My dad is a mechanic at the Chevrolet Dealer in Brunswick. He was lucky enough to get alot of performance training and was the go to guy on the hipo stuff. GM has/had a plantation nearby so the local lot kept all the prize Chevys. A young exec drops in, picks up a Chevy II SS L79. Well, it promptly spins a bearing and the exec is steamed. Pops picks the Duece up on the hook, and they snatch the motor. Long story short..... correct VIN stamp on a 283, not Double hump head 327, this car had < 25 miles on it. Exec starts detective work, busts an inside theft ring swapping reject engines for the good stuff. So could it happen, yes.... rare at best.

[pound41]

This is from the Book Chevrolet by the Numbers 1965-69
Engine Block Indetification Chapter page 67

Block#3932388
Very little is known about this block. It was Tonawanda cast and built. From all indications the block is identical to #3932386. It has been found in passenger cars with the 350/300HP engine code stamping. At LEAST 4 SS 350Camaros were built with this block, with casting dates ranging from L208 to B199. Atleast one Camaro was built in September 1969 with this blockOther cars could have recieved this rare block, but it is unknown which or why.
Most #3932388 blocks are dated from September to December 1968.
Newer information says 6. Mine is in my driveway

[RLONG]

Sounds like it is a 350?

[losangelesk5]

The numbers on my block are 3951511

[pound41]

Tonawanda plant 400 4 bolt main used in monte carlo stock 265hp

[D.PASSMORE]

Check the vehicle vin and see where the truck was produced. Could be a match,maybeee....

[m6z]

Originally Posted by RLONG

They started putting sb400 in the trucks in 72 and maybe some 71s i do remember that but i think in 70 it would have been a 396 that was called 400bb

Originally Posted by too much stuff

Not aware of any 400 small blocks in these trucks, blazers or burbs until after 72.
Not so sure about the 6 engines put in camaros with different numbers either. I am not saying it didn't happen, but highly unlikely IMO.

so yes or no? Any documentation to support a 400 sb in a 71/72 truck?

[too much stuff]

Originally Posted by m6z

so yes or no? Any documentation to support a 400 sb in a 71/72 truck?

I am still saying no. No 400 small blocks until after 72.

[m6z]

Originally Posted by too much stuff

I am still saying no. No 400 small blocks until after 72.

Ok. Thanks. That is what I has always thought as well.