425 Cad

Ok i just read the thread 425 cad good or bad?, I have a 425 cad with a 400 tran that is in great condition. I want something beefier than that though, i have heard that the basics such as the block are the same in the 425 as in the 429, 472, and 500, so i was wondering can i transform it into 500 or do i need to start from scratch. Any advice would help

 

Caddy work is expensive. If you want a 472 or 500 I'd sell the 425 and buy one IMO

 

Bolt in the 425 the way it is and drive it like that while your looking for a 500 or a 472,you can wake up the 425 with a camshaft swap and an edelbrock intake manifold + a decent carb or rebuilt quadraflop,the cam and the intake can be swapped onto the 500 when you find it.
Look up maximum torque specialties (MTS) for the best prices and parts selections

 

Nope....
For starters, the 429 is the same as the earlier [390 style] cad block. The 472-500 was an entirely different animal.

The 425 does share the basic architecture with the 472-500, but it's not really the same... It's sort of a light weight late 70's "emissions" version... They may look the same on the outside, but on the inside they are as different as night and day.

On the short block, you can use the pan and oil pickup off the 425, as well as the front timing cover, oil pump, brackets and pullies from the 425 to put on the 500.

The heads will physically swap between the two motors, but they will not work!
If you put 425 heads on a 500, you end up with 13:1 compression and runners in the heads too small to feed the engine.

If you put 472-500 heads on a 425, you get 6:1 compression........ Probably make a nice foundation for a turbo or blower motor, but NOT something you want on the street.

The 425 really isn't a bad motor at all. While it is a light weight [compared to the 500], it's still quite powerfull and robust, can be made to give good economy, and is very easy to work on.

Unless you just HAVE TO HAVE a 500, I'd say the 425 is a good engine to start a hot rod build with.