Need to fix LT4 intake

[383z]

Thinking of buying this LT4 intake for a good price, but it was machined to fit LT1 heads.
The seller says, “LT4 intake manifold machined to fit LT1 heads. You will not be able to use the LT4 race gasket as the manifold sits but it will work with LT1 heads and LT4 heads. If you want to use the tall LT4 gasket you will need to have extra material added to the runner where it was machined.”
I just bought AFR 210cc and I don’t know if they will fit "as is" without any problems.

Should I:

• Put the material back on
  
  • How much should be added?
  • How much it will cost?
  
  

I don’t mind doing that because I plan on getting it powdered coated another color anyways.

• If it will fit with no problems which gaskets should I use?
• Should I wait and find another one for more money?
  

[MoeHorsePower]

Not sure if that statement is true I thought it was the other way around, but just get which ever gasket you are going to use, put it on the heads and scribe then do the same to the intake and see how much if any of a mismatch.

[Fastbird]

You can see below the injector bosses on that manifold where it's been milled. Now I've never seen the process so I'm not sure if they add material to the runner to being the height down then mill or what, but that's what I'd anticipate. What you'd need to have done is material added to those bare spots on the side below the injector bosses, then scribe for the LT4 race gaskets and port out to match.

[Injuneer]

The factory LT4 intake has the same port shape as the LT1 intake. There is just extra metal, so the ports can be opened up to match the LT4 heads. GM ran out of money on the LT4 program, and never bothered to change the ports from the LT1 configuration to the LT4 configuration. You have to open the ports up to match an LT4 head with raised runners.

Here's an LT4 intake, ported to match ported factory LT4 heads, for comparison:

[383z]

Thanks for all the info. Buying this intake could save me a lot of money if all I need to do is add material to the runners, because I do want to port, polish, and powder coat the intake. I would like to reverse what has been done to the intake.
Does anyone know how much people take off the LT4 intake to fit LT1 heads?

[Injuneer]

I could try and measure my LT4 intake, but it may be difficult with it on the car. Might need to press a piece of clay over the lip and measure the indentation. I also have a spare LT1 intake in the garage, so I could give you the difference in measurement between the two.

Let me see over the weekend what I can do. Last time I looked, there was two feet of snow piled against that garage door.

[383z]

That would be freaken awesome if you could do that!

[383z]

Ok, I e-mailed Lloyd Elliot and he said he can add material to my LT1 intake and then machine it back flat to seal against the heads for $200 then fully port the intake for another $200 for a total of $400. I like the way this adds up and was wondering which gasket I would use of I go this route? Will I use the LT4 race gasket pn 12367777 now that it will fit like the LT4?

[Injuneer]

Can I assume Lloyd knows how much to add back on? I shoveled the snow away from the garage door, but I need to get some clay to get a measurement with the manifold on the engine.

[Injuneer]

Hard to measure, but it appears they added the 0.100" required to accomodate the LT4 head runner that is supposed to be 0.100" taller. My measurements for the width of the "tab" beyond the injectors, were 0.45" for the LT1 intake, and 0.55" for the LT4 intake.