stubbs

I was thinking of having it done, but I don't know of any North Jersey shops that do that type of work.
What exactly should I have done? I was thinking of kind of knife edging where the runners siamese apart, any other advice?

1racerdude

Have them Extrude Honed. Pricy but good.

ws6transam

http://www.ws6transam.org/car/tpirunner2.jpg
http://www.ws6transam.org/car/tpirunner1.jpg

Contour the opening on the plenum to match the siamesed runner. Open up the slot, drop it in another half an inch. Knife edge but not too sharp. Dont worry about polishing, just bugg it up with a sanding roll. Buy TPIS big mouth gasket set and gasket match the runner opening and exits to the gaskets, which you will modify by cutting out the divider, just like your plenum and runner. Then open up the intake manifold to match the big mouth runner/intake gasket set. Port the intake if you wish, but I highly suggest you buy an aftermarket intake if you havent already. If you already have the aftermarket intake, just make sure you have a smooth transition at the intake opening that matches the gasket and runner diameter.

stubbs

Wow, thanks for the info and great pics. I already saved them for reference.

stubbs

ws6transam I had an 83 Firebird that was the same color as your 84 I think. I have been looking for the color code, as I have been thinking of restoring an 87 Monte SS and painting it that color. Quick question, my car was like a gunmetal grey metalic, but every once in awhile at night under certain lighting it would almost have a brownish color, it wasn't brown but something of an optical illusion caused it to reflect like that. Does your car ever look that way at night? Is this an end too my long search for this color?
BTW that is one hell of a nice car.................brings back some memories for me.

That big linked pic of your car is now my desktop wallpaper, once again, damn thats nice, and I love it, wish I still had mine, but thats a LONG time ago for me.

ws6transam

Yep, that is what my color does!

Midnight sand-grey metallic. I'll look up the paint code if you want it.

stubbs

That would be great. BTW why the TPIS big mouth gaskets? Are they larger than an SLP gasket? How do I gasket match, just trim to size and port one side and then the same on the other I guess?

stubbs

Also what tools did you use to remove the metal from the manifold and runners?

ws6transam

http://www.ws6transam.org/car/portingtools.jpg

Six inch carbide mandrels, as found in Summit catalog or in a tool catalog.
Standard Abrasives kit, also from www.summitracing.com
Lastly a die grinder. Not necessarily a Ingersoll Rand like mine, but something that costs more than $19.

I used TPIS gaskets because they are nice quality, dont cost a fortune, and TPIS sends them out like same-day. In addition, they are big diameter. I spray some black paint onto the mating surface of the runner, put the gasket into place, then scribe a circle in each of the gasket openings into the aluminum. Then I spray the intake mating surface and do the same thing.

You then use the die grinder to hog out the aluminum up to the scribed line but no further. Then you use the grinder to taper the holes into the intake and into the runners and smooth out the radius. Lastly, you use the SA abrasives kit to sand out your grinding marks and smooth out the transitions. Your runners should now be a perfect match to the gasket and the intake, enabling the air to segway through the induction system into the cylinder head with little interference to the laminar airflow.