Maybe somone over here can tell me is a small block 400 a good motor?? what cars did they come in?? Anyone no where to get a core block???

thanks

 

The small block 400 was a pretty poor engine. Almost impossible to get any power out of them. Came in cars & trucks in the 70's.

Now, if you're willing to take out everything that the factory put in them, that's a different story. New heads, cam, rods, pistons - they'll scream.

Until the block cracks.

Best bet is to start with a new Motown 4.125" bore block. Fixed everything the factory did wrong, makes a great base to build a great engine. Prices start at around $1900. Then you get to put in the crank, rods, pistons, bearings, core plugs, heads. . .

 

400 small blocks are the ****.. you dont need aftermarket block unless ur lookin for something nasty.. so just put aftermarket heads on an new internals an u got ur self a 500hp monster

 

Hopefully the tongue implanted in cheek was obvious.

However, you don't want to start with a factory 400 block that is already .030"-over. The factory didn't put a lot of meat in the cylinder walls. I know 2 racers who have lost their 400-based engines to broken cylinder walls - one was an all-out set-up, the other one was a fairly mild 377. In addition, my dad bought a '70 Impala that had been traded in after the block cracked with 50k miles on it - the dealer put in a new block using the old internals. At 90k, it had to be redone for a broken piston. After that the engine went a long time, but just another example of poor factory reliability.

4-bolt main factory blocks are notorious for cracks in the main bearing web.

Can you build a good factory-block based 400? Yes. But, be careful, and invest a little extra in pre-machining work such as Magnafluxing and sonic wall thickness testing.

 

I would go one step further and say that the magnafluxing should be mandatory. I wouldn't purchase or build a 400 unless the block was magged. Most of the 400's came in trucks. In the 70's and early 80's, trucks weren't babied as they are today. They were horse whipped mercilessly! They were also last on the maintanance "food chain".