3500 Intake Manifold Porting

[jmgtp]

I keep reading that a stock 3400 intake manifold/plenum flows better than the stock 3500 (LX9) unit - however with a little port work apparently the 3500 manifold blows the 3400 away.

Where is the restriction in the 3500 piece? Is this something I can take care of with a 1/4" die grinder and some stones/bits? Pics, info, anything welcome.

Getting about that time where this motor is getting a lower intake on up gasket refresh. This motor is staying fairly stock but if I can squeeze a lil more flow for not much work I'd want to do it.

Other question...
Does the TB opening on the 3500 plenum have a large and unvarying diameter? I'm planning on fabbing an adapter to use a stock 96 LQ1 Tb (I believe 63mm).

[SappySE107]

64mm is the stock 3.4 DOHC TB size. Gasket match the upper and round off the inside. You have to port the lower and upper to the larger 3500 gasket size to have the most flow possible.

[robertisaar]

i wouldn't use a stone since it would get stuffed full of aluminum pretty qucikly and become completely useless.

[IsaacHayes]

Stones do suck. Trust me spent way too many hours with several......

I think the LQ1 96+ TB has the same bolt pattern as the 3.5L DOHC LX5 TB... so that adapter sold in the store *might* just work for it. I haven't had anyone reply back if it has the same bolt pattern or not. Sure looks REALLY close. Even looks like the same TB aside from the vacuum ports being a different size...

[jmgtp]

Ok I'll be sure to use a bit rather than a stone.
I'd send it your way Ben but I need to try to save some money on this swap without cutting corners.

What is a good bit made out of? High carbon steel? I had a cone shaped one that I used once and it wore out really quickly. I can't remember if I had been using it on steel or aluminum though. It was probably steel and I was probably being impatient and applying too much pressure. Any suggestions on what kind of bits to use? I'd like not to spend TOO much on a bit/bits.

The LQ1 TB is a 3 bolt and I'm prolly going to make an adapter out of steel since I have some thick plate lying around.

[SappySE107]

I have never worn a bit out on aluminum. Broken them on iron though. A carbide burr meant to cut aluminum would be best.

[IsaacHayes]

Felpro:
LQ1 TB gasket: 61029
LX5 TB gasket: 61304

Looks VERY close. I overlayed them in GIMP and the bolt holes were like a mm off, but the pictures may not be perfect... One has ports opened up for stuff the other doesn't. Either way a flat adapter with a hole for the bore is the only hole needed.

I bet you could use either TB... Need to pull these gaskets up at the parts store and find out...

[pocket-rocket]

This is the exact set I got back when I had the good intentions on helping Ben as best I could with porting at stuff. I also bought an aluminum cut (which cost almost as much as the 8 double cuts), but even on scrap pieces, that thing is too aggresive for my liking when it comes to material removal. It mows through aluminum like a fat kid on a batch of fresh double fudge brownies. I went as far as to get another air compressor hooked up out in my oversized shed, regulator with auto-oiler and all. That 8 piece set does do nice though. Just do like Ben suggested to me and get some WD-40 to dip them in to help keep them from getting clogged with aluminum.