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Porting your intake

Performance Mod 
8K views 12 replies 8 participants last post by  Dr. Johny Dodge 
#1 · (Edited)
Been meaning to get to it for too long. I found the lost photos so here we go :D

To start, the tool list.

Dewalt DW887 grinder. Worth every penny
non ferrous bits, the cutters. I buy long and short versions and cut the 6" units to 4-5". 3/8" tree shape is my favorite.
1/2" x 2" 80 grit and 120 grit sand rolls, the fat ones bend mandrels.
Mandrels for scotch bright balls and the sand paper rolls, long and short versions.

Burin Japanese chisel Antique tool Metalworking hand tool Drill accessories


The bit on the left is for aluminum, on the right is for iron.

Tool Tool accessory Cutting tool Metal Titanium


Taking great care to line up the holes with the gaskets mark both ends. Then look at what you did, you often see core shift at this point which is fine. Get your bits ready for cutting. Always use short, easy to control bits for cutting to the edges. Long bits are used only when you can't reach as they fail to easy.

Auto part Automotive engine part
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Always make sure to have light in the runners and they start cutting. Make sure to use the C clamp to hold the manifold.

Auto part Engine Automotive engine part Pipe
Auto part Steel Metal


I like to use the 80 grit sand paper rolls and both length mandrels at this point, this end of the intake goes pretty fast. I widen the manifold down into the runner. I make a nice inside turn in the manifold too to help flow. Then sand the whole runner as far as you can.

Auto part Tool accessory Machine Automotive engine part Pipe


The head side is the toughest. The bumps are long on the inside and don't match the outside. So you need to pinch the dents / bumps to check thickness. I can handle this by touch, if you don't feel safe you can buy testing clamps cheap. The top is easy, see how wide it is between the injector hole and the top of the runner? Split the difference and blend back at least an inch. Then widen to the gasket, easy but go slow. Blend in 3" on the sides. It is ok to leave a little ridge from the cutter on the bumps at this point.

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now switch over to 80 grit and sand the whole runner, going long and short mandrels.

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Then do the same thing with the 120 grit.

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Auto part Metal


Next up is the polish balls, I like to use medium and fine. Tough to get medium in the ports lol. The fine ones seam to work best but don't hit the rough spots as well.

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Next I use the belt sander, very lightly to sand the surfaces. This cleans and flattens them.

Machine Machine tool Tool and cutter grinder Tool accessory Tool


Lastly I stick the plenum on and check my work, nice funnel into the runners, no sharp edges or corners for the air to get in is key.

Light Ceiling Metal Aluminium Steel
 
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#3 ·
Yeah you go to the gasket for a plenum. I didn't add how to port a top piece, but it isn't much different. The lower piece though doesn't get cut much, I just take 1/16" off all the way around and then sand them. Shadow goes to the gasket and then opens the top to the plenum that big. He mentions he really hogs out the top. I believe that the world of plenums is here to stay, so learning to deal with the top piece is going to become if not already a waste of time.
 
#4 ·
After there is more questions ironed out I'll move it to the FAQ section with other mod threads.
 
#5 ·
I think the explanation of why you wouldn't port out the lower half of the head side of the ports should be explained here; No? :shrug:

I understand the theory behind it but, to be quite honest,
I've ported a few of these and, have had no issues.
I took the lower(head side) right out to the gasket.

But, on that same note, the heads I was mounting them to were also ported such that the transition was a smooth one.
There IS a "dip" in the path of flow but,
IMHO, it's better to keep the area larger for volume of flow.

I have no flow comparisons or, any data for that matter but,
the cars with the manifolds I've ported ran WELL.
 
#7 ·
The pinch point in the intake that kills flow is at the injector. So when porting the intake your making it wider and taller in that area. But as the 78, 287 and 445 heads don't have the larger port you don't lower the floor.

Dropping that floor is only done with the 655 heads and requires welding, but this is different as you increase the volume of the intake in flow to match the heads ports. Doing it to the other heads doesn't work the same.

As discussed before, the G heads got a lower volume runner and a raised floor to increase velocity in a NA engine running low volume for more power. NOT a turbo charged engine with 4 times more volume moved.

Another thing about physics here that many don't bring up is that density increase lowers flow volume. This is why you build wet intakes much different than a dry intake. You add a 1050 Dominator carb to a single plane intake on a street small block and the engine falls on its face and won't run. However, a 1000 CFM 4 barrel TBI and injectors at the head and all of a sudden that intake has lots of mid and some low end power again. When you port the manifolds and the heads you increase the volume, but when boost goes up the density goes up. Then the physics of fluid flow come into play alone with "wet" intake design.

When you flow bench a small port head, the flow is getting killed off above .500" lift on the flow bench with big valves. At that point the port is not enough to feed the valve. When testing the 655 that is much different, the head can handle another .150" more lift for flow. The larger port isn't trying to stall at really high lift. Add that to a high density mix from pressure and the port move more air under pressure before the port becomes a restriction. The Ford 2.3 guys have killed the 2.2 people a long time, there heads don't look that great on the flow bench but there ports are larger than our 655 heads. Which BTW have the same size ports as the Neon head.

Should also mention that with this intake it is designed to move high density with the polishing, but that isn't best shoving fluid though there at low volume. So if this thing had a carb sitting on it it would puddle fuel. But of course were not running carbs lol. But you always hear some one bring up, "but it's too shiny" BS that read that some where in a book for building muscle cars :drinking:
 
#9 ·
maybe I should show a stock intake next to this one? Didn't think about that lol. But there are before pictures I suppose with marking the manifold
 
#10 ·
great write up. it would be nice to see a "before" close up picture of the head side port before you started so it would be more apparent (to us novices) of the work that was done. inserted as the first pic where you currently show the first two shots of the partially ported port.
 
#11 ·
I see things done, before I start. In construction or porting. Maybe another manifold on top would be nice or side by side.
 
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