Originally Posted by Kjtw
Found a set of heads from a 76 corvette with ser # 333882 , would these heads help give my target master more compression and hp ?
No these are essentially the same head as the Targetmaster, different casting number but the same specifications for the combustion chamber which is essentially an open chamber of 74 to 76 ccs, the spark plug placed to the extreme of the chamber wall. Corvettes starting in 1972 through 1987 did not get anything special from regular production heads, emissions being the rule no matter the advertising.
1988 saw the L98 head in iron and aluminum these were used on a lot of Corvettes and Z28 Camaros with 350 engines. Lower output versions got cast iron, higher cost and power engines got aluminum. Functionally they are the same whether iron or aluminum. These in cast iron also found their way onto many marine engines. The L98 heads reintroduce the 64 cc double quench chamber of earlier preSMOG heads but with the spark plug moved well into the chamber center as is done on the following L31 Vortec.
The L98 head can be a little tricky as some were drilled for the older 6 bolt intake pattern of all bolts being 90 degrees to the intake gasket surface of the head. Most were drilled with the center plenum side pair of bolts at a 72 degree angle, obviously the intake must match. The factory did not build a carbureted version so carb intakes that fit the 72 degree plenum bolts are rare even in the aftermarket. Professional Products and Pro Comp make a convertible manifold with a flip over gadget that will orient to either plenum side bolt angle. Another head with the same bolt pattern and chamber is the LO5 Swirl Port of 1987 through 1995 truck and some full size passenger car 350's. An overly condemned head for its less than ideal high speed breathing, it nonetheless makes a good grunt head under 4000 rpm.
1995 trucks bring the L31 option Vortec 350. That head is a line in the sand. There's before L31 Vortec performance and there's after which is a whole new look at performance. This head has been copied and improved on by the aftermarket available in iron or aluminum from affordable for the average guy imports and some relatively modest priced domestics to outrageously priced race only toys. Generally the cost of rehabbing a old set of heads with rebuilt seats and valves, conditioning the guides and dressing the gasket surfaces is about the same price as new set of L31's or import heads.
The L31 actually draws chamber and port concepts from the 1992-1996 LT1 and LT4 heads of these reverse coolant flow engines. These heads don't fit conventional coolant flow blocks without a lot of expensive head modification, doable but hardly an economical modification. Been there did that, yes they rock, but you need to be or have available a damn good welder and machinist.