Originally Posted by Red neck blazer
I have a 79 4 bolt 355. And was wanting to stroke and bore a little more. But can i get a set of vortic heads that my holley 4bb in take will fit. Or if i go vortic then do i have to buy a diff 4bb intake. Or is all this just wishful thinking and ill have to go fuel injection with the vortic. And how hard would it be to wire up a vortic in my 86 blazer. And what is some of the other things that would have to be changed in the truck to make it work? Thanks guy i kno that yall will know the best way to go. Thank agian
There are three GMPP Vortec heads and a few variations individual sellers make available as semi-production mods.
125508060 is a part number of the original 1996 & up production Vortec. It can be made from either a 10239906 or a 12558062 casting. The difference between them is that the 906 uses hard seat inserts and the 062 uses induction hardening. Scoggin Dicky among others sell a modified version for cam lifts over .45 inch at the valve. This head requires a specific intake that has raised runners and the Vortec unique bolt pattern, GMPP and Edlebrock supply units for a carb. Keep in mind this head does not have a provision for exhaust heat to the intake and if you need EGR it has to be externally plumbed.
GMPP has also released part numbers 25534421 and 25534431. These are Vortec style heads with heavier casting thicknesses and larger 2.02 and 1.55 inch valves, they accept higher lifts without modification and feature a 180 cc intake for the 421 and 206 cc intake for the 431. These are complete ready to run heads, they are also available under a different P/N as machined but bare. The original Vortec "060" heads all use 1.94/1.50 valves with a 165-170 cc intake port. These use the standard Chevy bolt pattern for the intake but the intake still needs to be a raised runner type.
Putting a complete injected Vortec into a non injected, non computerized vehicle is a big project, not impossible, but a challenging effort. You need the computer, wire harness, sensors, injection pump and lots of detail parts. Additionally, the computer needs information from the transmission and about the vehicle that older vehicles can't supply without modification to the transmission, installation of A to D converters or replacement with a Vortec era transmission. There will be problems with instruments such as the speedo, requiring a converter, or outright replacement to an electronic unit. Like I said not impossible but an extensive and technically challenging swap.
Unfortunately, the Vortec injection isn't that great, any type of performance work and for general reliability these systems are usually back dated with port injection parts from older TPI systems.