I bought a set of MTI heads, and now I want to port my intake. Any tips? Key areas to hit?

 

Do your best to radius the intake to each runner.

Clean up all casting lines.

Match to your throttle body - TB outlet should be slightly smaller than the intake hole, so it never sees a ledge in the flow of the air as it enters the manifold.

If there is anything you can do to clean up and smooth around the injectors, inside the runner, do it.

I recommend a trimmable Felpro intake gasket set, if available. Glue em down to the head side only with gasket cement. Put a little dark grease on the outward gasket face, really try to center and align the intake on the motor and torque it up overnight and you'll be able to see the exact clamped shape and location of the intake runners. The pattern of grease on the face of the intake will show the shape of each port (mark them carefully with a scribe, then get rid of the grease on everything).

Then match the intake runners to your heads. You can open the manifold runners up with sanding wheels (you don't want to cut too fast). The outlet of the intake runner should be kept slightly smaller than the head so if anything you have a ledge there that can help with reversion.

If you feel there's enough material, you can open up the port, as long as you keep the basic dimensions and shape. Removing a lot of material here is not much of an aid, you want smooth flow with minimal interruptions.

Trim the gaskets to the head side. If you're careful and use brand new Exacto blade or razor, you can keep the gaskets on there for good. I like to stuff a paper towel down each intake port to catch gasket shavings when trimming. Then I remove them with a shop vac.

Clean well - do not use the dishwasher for this - don't ask me how I know- and put it back together right.

I found a Sears flexible shaft tool, like a large HD Dremel that works great. It accepts the larger Dremel sanding tools (like 5/8" and 3/8" head size). You can buy the Dremel sanding heads in bags of like 25 for $6 at Home Depot, and turn them around to get a little more life out of them. They come in 3 grits from 60coarse to 240fine. I use good lighting and and extra work light that I shine down the TB hole.

Use WD-40 as a very light lube and keep the sanding disks from loading up. Wear a face shield and have good ventilation and no HW heater or Furnace around.

Don't drink a lot of beer while porting - it doesn't look as good the next day...

With the sanding disks it is difficult to screw things up. The worst stuff I've done is skate the tool across the face of the outside of the intake, and left a mark.

Take your time, be patient and watch the tendency to rush the last 2 or 3 ports.

If you do all this you'll really help maximize your setup, letting those great heads you bought work their best with everything else.

Good luck!

Jim

 

Thanks for the tips man. I just got all my parts back from the machine shop for my 355, so the heads won't be on the motor until after I finish the porting. Sounds like you've got it down to a science. Hope I can get it right.

 

thanks here too, i'll be doing mine in a couple of weeks. :-)

 

is it possible to port the intake holes at the throttle body without taking off the manifold on an lt1?

 

I've seen a few posts where people have done it by stuffing a well greased up rag tucked inside, I wouldn't reccomend it though. If your going to port your intake and do it right like DeltaT explained then pull it. If it's never been pulled and being a 94 model it would be good to give it some fresh gaskets, fresh RTV sealant front and back, etc. GM had a bulletin or something years ago for the leaking intake back by the oil pressure sending unit, it just wasn't sealed good enough from the factory supposedly.

 

You must pull it to do it right. Once it's off you can freshen up like BRETTINATOR said. Good time to check Opti, all that. Might as well port the manifold and port match it while it's off. With all the work, you might feel the difference...

Jim

My Site: http://home.mindspring.com/~jim_fisk/id1.html

 

how do you port match it, you mean like the runners and stuff? just open them up or what

 

See my post up top.

Jim