Since our LSx engines use rubber o ring intake seals. We can no longer use the old fashion intake gasket as a templet method when port matching. Is there a "best way" to port match LSX Plastic intake to LSX heads?

 

I am curious also.

 

Did your intake leave marks on the head from the rubber o rings? Mine did. You can open them up to just shy of the marks. Or you can simply widen the intake runners up by about .050 on each side. The top wont gain you much flow, and the bottom varies too widely from head to head , especially if theyve been milled.

 

I wonder if if you could assemble the intake without the O-rings...if you put some bluing or some sort of die on the heads(machinest speak up here) then remove the intake and remove material accordingly.

It's a hassle, but the only way to get a true picture of port intake/head.

 

i would think that you could just get a big piece of paper, lay it over the head and tape it down, scribble over the ports and scribble over a reference point(s) (you know...the way you did in grammar school with crayons and leaves) - then cut out the marks on the paper, lay it over the intake, match up your reference point(s) and grind away - in theory that will work

 

OK, I'm with you, but how do you get a good reference point? If your heads are milled at all they'll sit lower etc...the only way I can think of for sure is what I described. Since I'm planning on doing this I would love to know an easier way.

 

I found this TIP in the advanced section concerning porting the FAST intake.

Quote "After talking to Tony Mamo I learned that the best way to match the floor of the manifold to the heads is to epoxy the manifold floor to match the heads. The manifold has a smaller corner radius at the floor than the port in the head. You will lose a little flow if you grind the heads to match the manifold. The corner radius at the floor needs to be kept large. Steve" Unquote

I am guessing "Try to grind and epoxy the intake manifold only" especially if your cylinder heads intake port locations are CNC'd much like AFR's. What kind of epoxy do we use?

 

There's a ton of ways to match the ports. The most accurate ones are a lot of work, which I can describe if needed, but for a one piece manifold (see other posts for FAST 2-piece) here's one similar to iam...'s suggestion that should do a decent job with being too much of a hassle:
1. Spray or brush a thin coat of light-coloured dye or paint around each manifold port opening.
2. Tape a thin sheet of cardboard (e.g. cereal box) to each head's manifold face.
3. Mark and cut clearance holes where the manifold bolts go through.
4. With a dirty finger, rub firmly around the port openings to leave a dark outline/guide.
5. Use a small ball peen hammer to tap around the outline, hitting at 45°, onto the edge of the underlining port opening.
6. The sharp metal will cut through the cardboard, leaving a perfect cut-out of each port.
7. Make sure the patterns are properly centered and that they accurately show the exact position of each port and then scribe, paint, etc. witness marks so you can see once the manifold is installed that they have not moved.
8. Apply several dabs of contact or weatherstrip cement to the manifold faces where they will touch the patterns and carefully lower the manifold down close to but not touching them.
9. Screw a manifold bolt in a few turns at each corner as a guide, then lower the manifold onto the patterns.
10. Press it firmly into place or snug down the bolts to allow the patterns to bond to the manifold, checking the witness marks to see that they have not moved.
11. Carefully remove the manifold and, holding the patterns firmly in position, scribe the port outlines on the manifold faces.
12. Remove patterns and cut/grind the last inch or so of each runner out to within about 0.020" of the scribe marks, blending the cuts smoothly back to the untouched portions of the runners.

Notes:
1.For smooth flow, it's far better for the runner to be somewhat smaller than the head port than even slightly larger.
2. Better too that the manifold ports should bee too small than that you should break through the wall of a runner!
3. In the highly-unlikely event that the port openings in the heads are smaller than in the manifold, it is worthwhile referencing the mismatch seen between the patterns and the manifold ports to determine how much metal to remove in order to flare the port openings to slightly larger than the manifold ones.
4. With the heads in place, this can be done by stuffing paper towels down the ports, followed by a squirt of shaving cream to seal the port to ensure no grindings enter the cylinder. Afterwards, it can be sucked out with a shop vac.

 

Good info

 

1.Tape over cylinder head intake port openings using Blue low tack painters paper tape. You can use one 2" wide piece per intake port.
2. Gently trim out intake port openings with sharp Exacto knife.
3. Apply brush or spray contact adhesive per can instructions to both the plastic intake opening port area and taped area around intake opening on head.
4. Bolt down intake.
5. Remove intake. The tape should be attached to your plastic intake showing you where to grind and/or add epoxy.
6. Remove tape and contact adhesive from plastic intake using lacquer thinner.
7. Clean intake, add seals, install intake.
8. In theory KICK ACE!

 

What kind of epoxy works best for our plastic intakes? Tony?

 

To The Top

 

Epoxy isn't a mandatory situation for good results but you could use the gold standard JB Weld which is easy to come by (usually found at most auto part stores, machine shops, etc.....dont get the stuff that sets quickly), or you can use a two part epoxy called "Splash Zone"....nicknamed for its ability to be used and actually cure underwater. MUCH more difficult to find...

Tony M.

 

just take one of the o-ring gaskets out of the intake and lay it over the intake port on the head, this will give you a very good reference

 

You need to know the relative location as well as the size of the mating openings. That's why a procedure like gollum's*, mine or about half a dozen other similar ones are necessary. *(must admit his has simplicity going for it; I'll have to think of some redeeming features for mine...)

 

If you've got access to an old ls1 intake laying around, just take a hacksaw and cut the side off it... Then you can lay the section right on the head and see exactly what you've got. I found that the left bottom side of the port on my heads hang over into the intake port just a bit.

http://mtfba.org/board/showthread.php?t=4320

 

I think the FAST intake will allow you to port match simply by removing lid and installing lower black portion of intake to heads for visual inspection. Look here.
https://ls1tech.com/forums/generation-iii-external-engine/461568-ported-painted-fast-90-pics.html