Gen. IV, V BBC's

[tiger9297]

When did they become Gen V's?

I have heard that you should not use a Gen IV head on a Gen V block b/c the water jackets were moved. Is this correct? Is anyone doing this?

 

[ARAMP1]

I don't think they moved, they were just different shaped. My buddy has been running into this problem. I wish I knew more about it.

 

[nvrenuf]

You're right there is a water jacket problem with this combination. Someone makes a conversion head gasket but I can't remember who.

I believe '95 was the introduction of the Gen V motor.

 

[hack500]

according to my book on big-block chevy's mkIV went to '90. '91 is when the Gen V was introduced. mark IV block has a 2-pc rear main seal. GenV/GenVI use 1-piece rear main seals.

I'm not entirely certain but iirc, stock heads can't be interchanged with different type of blocks. (i.e mk IVheads on a GenV block)

however, there are aftermarket heads that will work with either block - edelbrock and World Products come to mind.

 

[1-ton]

'91 is when the Gen V was introduced.

1991 was an odd year (as I know, that nvrenuf knows from first hand experience ). I did some research, and I have found that the Gen-IV and Gen-V where both available in 1991. The Gen-V Big Blocks went into the newer body style C and K series models (actualy it may have only been C series models), while the last of the assembaly line Gen-IV Big Blocks (L19 option code) went into the last of the old square body style R and V series of trucks. I wish I could find a good web site with definitive info on the different Big Block Generations, and their design differences.

 

[tiger9297]

I should have put this in my original post but the casting numbers on my engine are:
block- 10114182
heads- 10114156

www.moretec.com just says 91 & up for both. However, on the head it does say Gen. V.

The reason I'm asking is that I don't know if these "156" heads are worth a crap or not. I was wondering if some heads off of an older engine would be better. A buddy of mine has a number of heads including one 049. He has two 236s and according to 3 of his manuals they have the exact same specs as the 049s. I don't know why they would make the exact same head w/ different numbers but it appears that way. Anyway, I can buy these pretty cheap IF they are better than the ones I have and will work on my block.

 

[tiger9297]

You're right there is a water jacket problem with this combination. Someone makes a conversion head gasket but I can't remember who.

I believe '95 was the introduction of the Gen V motor.

I'm still relatively new at this but if the water jackets on the heads are in a different place than the ones on the block how does the gasket solve that problem?