I could probably look this up, but what is the difference between the 66 400 block and the 67 400. And would you prefer the 66 400 over a 66 Toro 425?

 

66 and 67 blocks are virtually identical. Date codes are different.

a 425 is obviously a bigger bore and can produce large power with less work as they did factory.

Both are great engines.

 

To expand just a little, the only substantive difference from 66 to 67 is the switch from B head castings to C head castings. Obviously casting dates on the parts will be different.

The 425 used the same forged crank and rods as the 400 in those years, as well as the same heads. The only internal difference is the pistons for the larger bore (4.125" vs 4.000") and the cam, depending on application. Oh, and the oddball 0.921" lifters vs 0.842" and 45 deg vs 39 deg lifter bank angles. Frankly, even I have trouble keeping those straight.

 

Mainly wanted to know if the 66 400 is a 45 deg block or 39.

 

The 66 400 is a 39 degree block as is the large lifter 66 and 67 425.

 

Pretty much the only differences between 66-67 400's are

The letter B vs C on the heads, and corresponding 6-digit casting ID
the date "year/mold#" digit on the block at the distributor
the exact application stamp in the front of the RH head.

Same intake, crank, pistons, lifters, cam bank angle, exhaust manifolds, water pumps, etc.

The Toro 425 is the exact same engine with larger pistons and some readily altered oil pan/ oil filter mount differences. With a similar design, and +25 CID, and the flagship ultra cautious assembly at the factory... the Toro 425 is the clear winner, assuming pesky details like casting number and application stamps and the like are of no concern. If they are, then change 'em to look right.

 

i think a better question would be ... if you had a 66 and 67 bare block side by side is there a means to tell the 66 and 67 apart ... understand the julian date deal, but since the casting id is the same, i believe there is no way to tell without the heads.

 

No, they are identical, and since Olds didn't stamp a VIN derivative until the 1968 model year, there is no way to tell.