i thought i'd start this because there are some differences in 5k & 4k blocks.

 

the 5k has 2, the weak one has a welsh plug under the water pump and welsh plugs down the camshaft side of the block. only ever seen one.

 

4k's, there were 500 made that had no strenghtening around the welsh plugs on the maniflod side.

i've struck 2 of these blocks in 15 years and both cracked through the plugs, one was in our rally car in NZ and the other was when i worked for an engine reconditioner here in brisbane, i told them about the problem, but they went ahead and reco'ed the engine, 2 weeks later back it came, you guessed it, cracked though the welsh plugs.

 

 

anyone else???

i had one of those unribbed 4ks. i had no idea they were so rare :P it's now slowly decomposing at ballina tip. the last pic here is the motor which is in my car as we speak

 

3k block

 

4k unribbed

 

4k ribbed

thats the best place for it

the other type of 4k block can be bore out to 5k, how to tell which block::

in one 4k block water flows between the cyls, on the other it doesn't.

the one that doesn't can be bored out about 5mm+

 

hope this makes sense