hey guys, what' sup, new to the board here. well i'm doing some work on my friend's 87 iroc z, 305 tpi, and well at first he wanted it rebuilt, but then i told him parts for a 305 are hard to find and now have convinced him to go to a 350, well we both work at a gm dealership and a month ago a 98 van came in with a oil consumption concern, 350 in that so we took that. now besides having to change the eprom, knock sensor, and injectors, what else needs to be changed? and what the difference between the 305 heads to the 350 heads back in 87?

Welcome to the board.

'98 van 350? Hummm, Vortec by any chance? The differences between 305 and 350 heads in 1987 3rd gens were basically chamber volume (58cc vs. 64cc) and intake valve size (1.84" vs. 1.94"). This '98 van engine, if it is actually a Vortec engine, has a different intake port/bolt pattern entirely from the '87 version.

305 parts aren't hard to find. It's harder to justify the expense of 305 rebuild parts (okay, the expense of rebuilding a 305) vs. the power gain from going to a 350.

What you could do is rebuild the '98 350 block, rework the '87 305 heads by doing porting work and the 1.94" intake valves, new valve springs (screw-in rocker studs a plus, too), open the chambers up slightly by unshrouding the valves, use a thick head gasket, and bolt them onto the later block.

Headers would be a good idea, too.

yeah, your right, i just got to rippin into the donor engine and i totally forgot about the vortec not having the egr ports in the head, oh well, if i feel like gettin tricky i might bore a hole in the head to open up the exhaust ports, but who knows, maybe i'll just work those 305 heads or get a different set.. any ideas on what to do? who makes some good computer chips for these cars with a set of 96 LT1 injectors (24 lbs) or a set of 30 lbs injectors?