Originally Posted by crussell85
I'm looking at installing vortec heads on my 93 k1500. Engine is the stock 350. I was looking at intake manifolds and the only thing I'm seeing is the Chevrolet Performance tbi manifold that will work with vortec heads. The manifold is just north of four bucks. My question is if I use the performer intake that I have on the shelf with a tbi adapter would everything work correctly? I know I will have to deal with the egr but besides that.......? Talking with my uncle he thinks I might have fuel distribution issues using a throttle body on a carb intake. He said cylinders 1&2 would always run leaner ( maybe to lean) then the other six.
Another question out of curiosity. Does the gm tbi system have better, worse, or the same distribution issues as a carb?
TBI adapter on a 4 barrel manifold works as fine as things work on a carb style manifold the adapter offers little disturbance to the TBI or the manifold. This is very commonly done given the gold plated price of the GM TBI to Vortec intake. Number 7 is by far the worst running cylinder on the SBC, not 1&2. Solution is either the old Duntov Z intake by Holley ( this steals some mixture off the excellent running #8 to crutch #7) or reroute the exhaust tubes on the headers so that 7 goes to the right side collector and 8 comes to the left side collector. The 7 to 4 switch cam just moves the 5 to 7 problem to the other side making a 4 to 2 problem. The TBI intake is very weirdly modified by the factory to try and correct the feed problems on the low side passages. The performer uses more rocket science than the factory's rather brut approach. You want to modify the coolant return when using the Performer to emulate the facory's 4 corner coolant return. GM uses a passage on the TBI intake to connect on the left side to the right which then becomes the bypass by way of the heater core or 3 way valve if equipped with AC. There is a flow restrictor on the intake, be sure to use that in what ever you come up with or be prepared to buy a lot of heater cores and clean up the coolant mess iin the cab.
I'd have to assume the Performer you have bolts to the Vortec's unique intake bolt pattern and will cover the raised intake ports sufficiently to get a seal.
EGR can be a problem the 93's TBI intake does not shuttle echaust between sides it only feeds exhaust off the right bank into a pocket that feeds exhaust to the EGR valve. If you have the 3706 than all you need to do is construct an exhaust feed from a header tube to the intake or use the 96 left side exhaust manifold and feed pipe for the L31 engine. If the intake is the non EGR 2104 then you'll have to fabricate a stand alone system. This is most easily done by building a mount for the EGR off a header tube. Drill the TBI adapter plate to provide a passage that accepts a fitting on the out side edge then divides into two passeges to feed each side of the TBI. Connect the exhaust mounted EGR valve to the adapter with a tube.
Running without EGR will require a custom chip that understands that the function is removed, the mixture between off idle to just short of WOT (where the EGR functions) must be richened by the reprogrammed chip or you'll fry a piston or two.