I recently started a thread concerning my confusion about Mark IV BBC head gaskets. I learned about series and parallel coolant flow and how to get the right gaskets. My thread about head gasket confusion. (http://www.chevelles.com/forum/ultimatebb.php/topic/9/18506.html)

I found out it would be easy to modify my BBC block from series flow to parallel flow, which is slightly better at keeping the temperatures across the block and heads more even. It sounded like an easy upgrade to be done with a little drilling and the right head gaskets.

Well, here is my block:
http://heartland.chevelles.net/RCstorage/engineblock.jpg

It sure looks to me like my block is ALREADY parallel flow, note the coolant holes below and between the cylinders next to the head bolt holes. Can someone confirm this? I guess what confused me are the two large holes at the back edge of the block which I thought indicate series flow (but which would be partially blocked by a parallel flow gasket). Given the earlier discussion, it appears my block has aspects of both seriels and parallel flow but maybe I'm just confused.

Do I need to drill a parallel flow hole at the front of the block to make it true parallel flow? It might help to reference the gasket photos in the previous thread. Or perhaps I simply have a parallel flow block and I just need to get the right gaskets and be done with it?

TIA.

All you need is the late (parallel) gasket.
You may find that the front hole on the right side & rear hole on the left side don't line up & will need to be oblonged a bit to match the gasket.

Yeah, just exactly what Wolfplace said. All the MK IV blocks have both the big 'n' little odd-shaped holes at the back. A series flow gasket has both rear openings, but not the three along the lower deck between the cylinders. Both rear holes are functional. A parallel flow gasket has the larger goofy-shaped hole blocked off, so only the smaller rear hole is functional, but adds the three holes between the cylinders so those three holes are functional.

The heads should work either way, without modification.

Originally posted by Wolfplace:
All you need is the late (parallel) gasket.
You may find that the front hole on the right side & rear hole on the left side don't line up & will need to be oblonged a bit to match the gasket. I'll certainly check the fit on the block but since I haven't modified the block in any way I assume it was manufactured as a parallel flow and thus should fit well with a parallel flow gasket. But the old saying "never assume anything" when building an engine certainly has to hold true!