I have a '88 IROC-Z with the L98 350 TPI motor. I am looking to replace the origional heads with a slightly better than stock approach. I have found some cast iron heads for around 600.00 a set fully assembled but I dont know the specs of the origional heads to compare everything to. I'm trying to make sure i dont take a step backwards by choosing the wrong valve size, CC, ect. I'm looking to find everything out i can about these heads, i have a gotten conflicting info from my search so i want to try and get it all in one place. valve sizes, spring set up, CC size, Ect. Hopefully this can become a reference for everyone on here.

 

They're nothing special, really. 1.94/1.50 valves, 64cc chambers, "standard" location intake and exhaust ports. Springs are 1.25" installed on a 1.75" nominal installed height (rotator/retainers used on the exhaust side). Typically they provide about 70 lbs. seat pressure and about 220 lbs. over the nose. Intake bolt pattern is typical 87-up with the two center intake bolts "stood up" at a steeper angle. The cast iron L98 heads used on the F-body L98 motors (-083 casting number) also have functional exhaust crossover passages, unlike the aluminum Vette L98 heads.

A truly bolt-in better head than stock in an 88' L98 application would be something like the Edelbrock Performer heads. Slightly larger valves, springs and ports, plus they're aluminum heads which saves some weight. They are definitely nothing like "race" heads. Just a mild improvement over stock but truly bolt-in (unlike many aftermarket heads).

 

i have looked a lot into the performers, but unfortunatly the budget peaks at around 700.00 so I found a set of RHS cast Iron heads, through an autozone of all places, fully assembled for around 600.00

 

Just to clarify are all 87-up intakes made with the steeper angle or was it just a TPI quirk on that specific intake/head matchup?