LT1 Intake Manifold porting...
 

Hey everyone,
I just recieved a ported intake manifold that I bought on E-Bay. The listing said that it was a fully ported manifold that was matched to a 58mm throttle body. Measurning the manifold, the TB openings are anywhere from 48mm-55mm & the holes arent even round. Looks like he opened them up with a hand tool. I have never used or purchased a ported manifold before. I am thinking that the piece I got is a hack job, but I want to make sure that this isnt normal before I start complaining.


Thanks,
Mark B

Thats not good, did the "porter" touch any of the runners?

Yes. All of the runners were worked. Although, to my untrained eye, they look pretty good.

Well thats good, but you should def clean up those two main circles. If you have a dremel get a nice aluminum router type bit and clean up to the full 58mm.

What other mods do you have. The stock intake flows well for the RPMs the LT1 run at ( below 7,000. Portnig the plenum/runners will have very little gains.

Can you post pics?

The front should be opened to match the throttle plates. Internally the runners should be opened up to match the heads. I have stage III porting on my intake and heads, they match Felpro race ports (mine match the Felpro 1207 I think ). Stock the plenum and runners have a semi ruff finish, when ported they would be smoothed.

The key to better flow in the LT1 intake isn't really the runner cc, the plenum isn't that big that it will support excess runner size. What you want is to rework the leading and inward edges of the runners to promote better air flow into the runners. Also the area under the injectors should be opened up to ensure the gas is being sprayed onto the valve and not onto the intake which could cause fuel drops to form (or puddling).

but with all the above said, The only thing you really need to worry about is that the a 58MM throttle body gasket matches the porting is correct, if the holes aren't right you could be close to the gasket edge which could cause vacuum leaks. There isn't allot of gasket surface.

Well at least he didn't go out and buy the edelbrock intake....

LOL!

So what should I do? Return it?

Clean up the intake holes, and slap it on your car. It can't hurt.