I am working on getting a 1995 454 54mm TBI unit together for the 383 I built, which has an Edelbrock 2912 Victor Jr 2 barrel Vortec intake on it. Issues I have come across are:

-In comparison to the small block tbi on my 92 Camaro parts car, the vacuum nipple going to the MAP sensor on the rear is not present, nor is the nipple for the EGR on the passenger side.

-The intake has no provisions for any vacuum accessories. On the stock 92 Camaro intake manifold, there is a brake booster hard line on the drivers side, and a fitting on the rear feeding a hose that runs into the wiring harness.

My questions are:

-How can I remove the rear vacuum nipple for the MAP sensor from the 305 TBI unit? It looks as though the big block TBI would take it as is, just the hole only goes down so far and then stops. I think all I'd need to do is drill that hole the rest of the way through, and drill a hole from the underside between the throttle bores. What do you think? Here are 2 pictures of mine, last picture is by dctrumpet on here:




-What is the rear vacuum nipple to the intake manifold on the 1992 Camaro going to? Can this be run from the port for the heat riser on the TBI?

-Am I overlooking anything by drilling and tapping into the plenum of my intake for the brake booster? I installed the intake onto the engine before realizing this.

Thought I'd ask before I go and potentially ruin a bunch of stuff. If you can help me, thanks!

 

Anyone know how the hose nipples are held into these? Can I heat them up and pull them out?

 

I wouldn't expect success heating the tube and trying to pull it out. Heating the casting..maybe. Overall, don't count on getting the tubes out while still being in any condition to re-use.

You're better-off to make new ones from double-wall seamless steel tubing--sold at every parts store in America for brake and fuel plumbing. The stuff is sold in "sticks" of 2--3--6 feet, or coils of 25 feet and longer. You'd do fine with the shorter lengths. Not expensive at all.

Cut the factory flare off using a brake-tubing cutter. Use your flaring tool to begin a double-flare, but don't squeeze hard enough to complete the flare--just enough to put a bead at the end of the tube to retain the hose. Then measure back from your bead to get the length of the nipple, plus the amount pressed-into the casting. Cut to length as needed.

Drill the casting to suit the OD of the tubing--3/8 for PCV or brakes, smaller for other vacuum accessories. Push the tubing into the casting with a bit of thread-locker to hold it in place, and to seal it.

 

They are just press fit into the casting. You MIGHT be able to twist and pull to remove them, but you'd likely just mess them up.

Schurkeys idea is best for putting into your new TB. You don't HAVE to flare the tubing, if you're running NA, if the hose is a tight enough fit for vacuum.
you'll also probably want to under size your drill slightly if you're drilling by hand or you might not get a good fit of the tube, but you'd be at a press fit this way.

 

Thanks guys! Good idea with the tubing. It is the little nipple on the back, I'll have to take a measurement tomorrow and see what I can do.

 

Got a vacuum nipple out the rear for the map sensor now. They didn't have stainless tubing at O'reilly, so I used this 1/4" green coated stuff. I put the line into my flaring tool sticking out about half as far as I usually would to start a double flare, and only pushed the button into it to get it to look like this:




Had to drill the passages through to meet, checking depth frequently. My tube measured .252" od. Went in stages up to 1/4" drill where the tube was inserted, using a D drill before final size and went in about .600" deep and the tube fit the hole pretty tightly. Put a little red thread lock on the tube and tapped it in fully with a brass hammer. I'm pleased with how it came out. Thanks again for the suggestions, guys. Saved me a lot of hassle.

I don't recall what sizes the small drills were, just sized the passages to whatever drills fit in the 305 tbi unit well.