So I have upgraded my engine with 062 Vortec heads, cam, and GM TBI Vortec intake. Cam is mild and not radical. Dynamic EFI computer upgrade,

I have eliminated the EGR on the engine. Before I get the legality issues involved with that, classically titled vehicles in this state can have Mods made without it being illegal. That aside, my question involves vacuum lines on the TBI unit. With the elimination of the EGR valve how do I setup my vacuum lines. I know the large port in the center goes to PCV, one goes to the Vapor cannister. Can the AC and EGR vacuum ports be blocked off?

I also am adding a VAFPR to the TBI. Do I need to tap the manifold for a vacuum port since there is only one port on the intake.

Any help appreciated.

Julie

 

The port that goes to the vapor canister is important in the sense that it is 'ported vacuum.' The throttle blades need to be open some to get vacuum at that port. So it is dedicated to the CCP canister solenoid.

Either of the other two ports can be used for the VRFPR. With the unused one capped off.

Someone recently (I thought it was Schurkey) posted a picture of the front ports with them being labeled. However I can't find the thread. It may have been someone else that posted the picture(s).

RBob.

 

Thanks RBob, that answered my question.

Another quick question. With the engine mods I have made I should be around 325-350 hp. Should I go with 46mm or 50mm bored intake? I am just worried that if I go with the 46mm bored TBI, that the cfm flow wont be enough.

Any input appreciated.

Julie

 

I would go with either a Holley TBI intake or a carb intake with an adapter plate. The stock intake and the Edelbrock TBI intake are too restrictive at that HP level.

IIRC, the Holley TBI intake is already at 50 mm.

RBob.

 

RBob, do you know how that Holley stacks up (no pun intended) to the stock manifold where installed height is concerned? We have so little hood clearance on these cars, I just wondering if this intake made the use of an aftermarket air cleaner a necessity.

 

So the GM Vortec TBI (12496821) intake is to restrictive even if it is bored to 50mm?

 

those numbers are very optimistic, most of the people that run 062 Vortec heads, LT1/4 hot cam, and GM TBI Vortec intake. are claiming dyno number around 250hp at the rear wheel, it is basically same setup for my build, like RBob said, it's because of the intake.

https://www.thirdgen.org/forums/tbi/...ck-3704-a.html

 

Optimistic? I thought I was being conservative. HP at the rear wheels will not help with determining cfm needed on the intake side.

Stock 1988 TBI 350 was around 170-180hp. I had the engine bored .040, some internal oiling mods, mild voodoo cam (446/448 lift), vortec 062's stock int/exh, exhaust headers with 3" dual system. I thought i would see at the minimum of around 300hp at the crank. I could be wrong.

I figure I would need a minimum of 528cfm at 6000 rpm. Openeing the GM TBI Intake to 46mm should get me close to that number. The TBI unit has been bored to 46mm and all other modifications possible done to the TBI for maximum CFM's.