I plan on installing vortec heads on a 327 Chevy using the factory TBI and installing the motor in my 1989 4x4 that currently has a 4.3 liter vortec. Everything that I have read says that this is an easy swap and everything should bolt right up.
I ordered the Heads from JEG’S for a little over 500 dollars for the set. After weeks of research by reading everything I could get my hands on dealing with porting and polishing cylinder heads. I applied what I had learned and worked a set of 882 and 193 Chevy heads. I wanted to get some experience before I attempted porting the vortec heads. Once completed, I used a hacksaw and cut the heads in half. I closely inspected the walls to see just how close I was to going into the cooling ports. I finally felt confident enough and I pick up a Dremal and started to grind the vortec heads. I numbered and removed all of the valves. My next move was to grind the valve heads down on two old valves. I then placed them into the chambers to protect the seats and started to polish the combustion chambers one at a time. I didn’t remove much metal just enough to smooth out the surfaces, after all I do not want to change the compression ratio. I figure I will have ten thousands shaved off just to keep the chambers at 64 cc. My next step was to grind down the exhaust bosses, port the bowls, and to remove the rough casting surfaces in the exhaust ports. I did not remove very much metal on the short side, just enough to get the surface smooth. I also didn’t gasket match the exhaust ports I retained the stock size. From there I went to the intake ports and gasket matched them. I did not remove any metal on the floor or the sides of the ports, once again just enough to smooth out the surfaces. The entry points on the intake were opened up quite a bit on the roof and on the short side of the intake. All of the walls were made the same and they all have the same matching angles and bevels. I then went to work on the intake bosses and ported the intake bowls. I proceeded to polish the exhaust ports, and then smooth out the intake runners. I did not finely polish the intake runners and bowls. I have heard that that would cause the fuel to puddle up. I ended up with mirror finishes on the chambers and in the exhaust ports. The very last thing I did to the heads was to smooth up the inside and underneath, all of the places where the oil likes to puddle up, clog up, and solidify after several thousands miles of use.
Take a look at the pictures and see what I have done to these heads and please give me your honest opinions. Has anyone swapped a 4.3 liter for a V8? I plan on keeping the stock TBI system, but I am going to installing the bigger TBI from the 350. I want to run full length headers with after market Catalytic converters with duel exhaust. Retaining the stock engines EGR valve, Oxygen sensors, and smog equipment. After all I need to keep the motor smog legal for New Jersey vehicle and emissions inspection
The TBI manifold for the vortec is very pricey. I have seen where some guys have used an after market vortec four barrel carburetor intake (which is half the price of the TBI intake) and made up a plate that bolts the throttle body to the intake. Would this cause the engine to run improperly or rob the engine of valuable torque and horse power?
