I'm heading out to a couple of area junkyards with acres of cars with engines still in the vehicles. I know from mortec.com that these can be found generally in 1970-1980 model vehicles. Which vehicles should I concentrate on for finding one??? I would think the heavier monte carlo types, big vans, and 3/4 ton trucks...

Any advice is appreciated

 

Well, my 400 came out of a '74 Impalla. According to a book i have 400's came in some full size cars b-dodies, Chevelles, Monte Carlos, Bel Airs, Caprices full size truck K-10 to 2500 C-20 to 3500. I would look for the years between 1970 to 1980. Most of the cars quit having them roughly around '76. so anything between '76 and '80 i would look in the truck.

 

A helpful quick glance check is the 400 will have a round buldge just in front of the motor mount area to accomodate the larger bore. Kind of like a regular SBC on steriods. Not a large buldge but it's noticeable. Other SBC castings are flat in that area.

 

I have an '80 casting 400 in my bird. Don't waste money on a 4-bolt main block. They are known to be weak, since so much material is drilled out of the bottom end.

 

Four bolt mains aren't bad necessarily but don't pay more for it than a two bolt block for the reason Ward said. If you do get a four bolt, you can use main studs instead of bolts and you'll be fine to 6000 rpm. Studs pull evenly between the cap and the main web instead of pulling mainly on the web with bolts. Studs take alot of pressure off the web.