Originally Posted by Port333@aol.com
I have a set of LT1 Small block Heads the casting # tells me they are from a 1992 to 1997 LT1 Gen 2, I would like to use them on a 1979 350 Small block Z 28 Engine. I notice that the cooling ports are different
Will these heads work and what do I need to do?
The large coolant passages on the deck ends have to be welded closed, otherwise they will gush coolant into the interior (oily part) of the engine. Then since this distorts the gasket surface and leaves a glob of weld above the surface the heads have to be milled to restore the surface. Then the head has to have a regular coolant hole drilled partially into the patched area.
Then a coolant return hole has to be made in the front of the head for fittings to bring coolant to a collector box you'll have to fabricate or make by modifying a catalog item similar to what you need but not quite right. On the back of the heads is located a vent hole this needs to be either plugged or exploited with a fitting that can feed the heater bypass circuit.
You will need to purchase a carb style LT1/4 intake this is a GMPP kit that isn't too cheap, it's made to modify the LT1/4 from EFI to carb with a conventional distributor so it includes some stuff you don't need to terminate the Opti-Spark system of these engines.
Over the years I've done a few of these and in fact run a conversion on my S15. There really isn't a foolproof and inexpensive way of rerouting coolant to return via a conventional Gen I manifold. To do this still requires the plugging, drilling and milling on the gasket deck plus adds drilling into the forward cooling jacket and welding in a passage to route cooling to the manifold face that doesn't leak into the oily parts and at the same time provides a top end head oil return, so this adds a lot of complication and cost to the simpler way I discussed above.
I'd recommend you either sell these heads to a collector or buy the bottom end that fits them. However, I so love the LT1/4 that I recommend you sell the heads rather than buy a short block that fits them. This engine is a difficult and unique aberration on the SBC that is expensive to maintain and is really unconventional at most every problem it tried to solve. It's just a PIA unless you're really into these things and have the time and/or money it takes to mess around with them.