Difference in V6 blocks
 

What is the difference in the engine block from 305 to 351 to 379 to 401? Is it just to cylinder bore diameter. I understand that heads will be different as well as carburetor options. I'm wanting to know about the block only. Thanks for any incite.

Re: Difference in V6 blocks
 

305, 351 and 379 all use the timing chain. 401, 432 and 478 do not as they use a gear style camshaft drive. This means there is a difference in the main oil galley to supply oil to the middle idler gear. However, a 478 or 401 is easily modified to take a timing chain.

Also my 478 has extra oil drains for accessories and governor oil connections. Bellhousing bolt patterns are the same as are the front cover bolt patterns and motor mount connections. Main and rod bearings throughout the range are the same except for the 73-74 478 which have larger mains. Pete Chronis told me this.

Re: Difference in V6 blocks
 

This is good information. So, I can take a 305 block and bore it to a 351 or a 379 and all I would need to change is the pistons?

Re: Difference in V6 blocks
 

You would have to improve aspiration.

Re: Difference in V6 blocks
 

351 and 379 pistons have different piston pin height - same diameter but different compression height and longer rods.

Re: Difference in V6 blocks
 

Unfortunately, it isn't that easy. This would require sleeving the block, otherwise, the cylinder walls will get too thin. The castings are different for each block because the bores are different.

If you want power, your best bet would be to obtain a 351 or 401 with a 6 bolt flange (if you want a direct swap into a pickup)