September 04, 2025, 03:17 PM
Bruce WilliamsMark IV BBC head on gen 5-6 block
Looking for real world experience with using a early style BBC Mark IV cylinder head on a later model gen 5-6 block.
The Mark IV gaskets (Felpro 1017-1) have two large coolant holes at the back of the gasket to allow water flow up into the cylinder heads.
The(Felpro 1047 or Cometic 5330-40) gasket only has one small hole at the rear.
With out drilling/punching a second hole in these two gaskets have you found less cooling due to the one small hole?
Does any one know of other head gasket PN that are suitable for this head/block combination?
September 05, 2025, 10:43 AM
GoobI think it was a Fel-Pro 1067 I used on a Gen V 555/565 with Brodix heads.
It had been originally built o-ringed with a copper gasket. There were no big bore composition gaskets at the time.
September 05, 2025, 07:38 PM
Bruce Williamsquote:
Originally posted by Goob:
I think it was a Fel-Pro 1067 I used on a Gen V 555/565 with Brodix heads.
It had been originally built o-ringed with a copper gasket. There were no big bore composition gaskets at the time.
Thank you
September 06, 2025, 12:05 PM
GoobIt's been some years ago, check the #1057 Fel-Pro also.
As memories come back, there may have been some special instructions regarding the water ports, or the gasket might have been specific for the Gen V block.
I hated everything about that block....weird oil pan, oil pump, timing chain and cover.....etc.

But it ran good, 5.40's @ 128 in a 3000# door car.