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So you want to port your intake manifold?

tweakedlogic

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I am no stranger to porting. I have ported every intake and head that I have installed on my vehicles. So while I was fixing a coolant leak from the lower manifold behind #6 cylinder, I decided to get the die grinder out.

First let me state that if you decide to port, you assume all risks.

I do not recommend you do this with a dremel. It can be done. But it takes longer, it is harder to reach deep, and you will use many more sanding rolls.

Most people think of porting as gouging out the head for massive flow. This is not true in most cases. the best method is to simply smooth the flow for less restriction. Keep the ports as close to stock as possible to maintain high velocity of the intake charge. Really all I do it remove casting imperfections and irregularities.

This is not something you can do in an hour or two! It took me two hours just to get the lower intake manifold off. I spent about 3 hours porting the lower manifold. Patients will pay off in the end. try to rush things or use a bit that is too aggressive and you will damage things or make you motor run poorly.

We are not reshaping or enlarging. Only smoothing things out. Primarily I pay most of the attention to the outside bend of the port. That is where the air will be flowing. Kind of like a weight on the end of a string. That is the most important part of the port. I don't care what the outside of the intake looks like. And i spend very little time on the inside of the bends. I only want to improve flow while keeping velocity high.

First you will need a mini die grinder (variable speed). They cost about $30-100 depending on the brand and the store. Snap On is very proud of theirs. you will also need sanding rolls, the shank for said rolls, and some 200 grit emery cloth.

I use the $22 package of rolls from Harbor Freight. The kit includes two shanks, tapered rolls and straight rolls in two grades, 80 and 120 grit.
image_3691.jpg


First remove the lower intake manifold. I will not cover how to do this. If you don't know, buy a manual.
Separate your sanding rolls first by type, then by grit. you will not need the 120 grit until you are 80% finished.

Clean, clean, clean. All of that oily carbon will clog your rolls. It has to go. It is best if you have an adjustment to control your top speed of the die grinder. if you spin it too fast, the rolls don't last as long and they fly apart.

Start at the top of the lower intake manifold. I left the fuel rail on. I did this because it does not line up perfectly with the ports. i wanted to correct that as much as I could. Plus it left me with an extra upper intake gasket i can use later.
IMAG0027-3.jpg

this is a pic from the top of the #6 port before porting. Note the bulge on the very back of it. the other ports don't have this. Do not try to remove all of that bulge. there is not enough metal. We will shape it slightly to reduce the restriction.
Begin with the 80 grit straight rolls. One port at a time. You are only going to rough in the port at this time. Don't worry about the corners of the port until you have finished with the straight rolls. Get to 80% finished with the straight rolls, then switch to tapered rolls. It does not take much at all in the corners.
Don't over do it. you will not be able to remove every imperfection. Think of it like this... Your truck was running fine with all of the restrictions before right? no need to waste time. get it close and be done.
IMAG0028-1.jpg

you want it to look about like this for now. this is about 80%. Perfect for where we are. Make every port look like this before moving on.

IMAG0029-2.jpg


See the line all the way around the top of the port where the fuel rail mates up? and the divot in the middle of port? Leave those. They are nothing to worry about. I know it's on the outside bend. But trying to smooth that out would take too much material away.

IMAG0031-1.jpg


To be perfectly honest, I cheated here. I used a stone with a very light touch to knock down this bump a little. Unless you are experienced i don't recommend you do this. Stick with the sanding rolls. All you want to do is reduce the bump and smooth the flow over and around it. It should look like this.
IMAG0056-2.jpg


Now we are finished with the top of the ports. On to the bottom part. (head side) Still using 80 grit and still only sanding to 80% finished port. I found it best to use a bench vice with soft jaws (wood) and clamp the mani on it's side so you can get to the ports without it scooting around. work one side at a time.

I took a worn out roll and scuffed this port so you could see what it is we are really doing hear. All of the shiny parts are high spots. We are only removing the high spots.
IMAG0044.jpg


Remember, a smooth delicate touch.
This is 90% finished.
IMAG0051-1.jpg

IMAG0052-1.jpg

IMAG0049.jpg


Nearly there. Patients.
You now have the entire lower intake manifold 80% finished. You can go ahead and install this for some minor gains (after cleaning). But why stop here? Another 30-45 minutes and it will be perfect.
it is time to switch to 120 grit rolls. Same deal. start with the top do every port with straight rolls, then switch to tapered. Then repeat with the bottom.
It should look like this when you are finished.
Top
IMAG0055-2.jpg


IMAG0056-2.jpg


Contrary to popular belief, you do not want a mirror shine. I we say polish, but if you get it too slick you will hurt performance. Think of the port surface like a golf ball. those little dimples help the ball to spill air around it to fly faster and farther. So with that in mind you can consider this finished. Just because I was taking pictures and making a write up, I decided to use little pieces of 200 grit emery cloth on the end of my finger. to remove some of the sanding scratches. It takes another 30 minutes to do this.
IMAG0058-2.jpg


I was hoping this pic would turn out better. You can't really see inside the ports, but you can see the studs I placed in there to hold the gasket for the valve covers. Nice little tip that will prevent much frustration.
IMAG0063.jpg


So now you are finished. I have not yet ported my upper. this isn't a big deal to me now because i have an extra I can work on later, and I already have a spare gasket. I will add that to this write up when I finish it.

Use brake parts cleaner and compressed air to really clean your parts before you reinstall. Every nook and cranny must be free of the dust and grit you just created. Use your die grinder with a 3M scuff pad on the gasket mating surfaces first.

Congratulations, you have improved air flow and cleaned of all that carbon.

Ideally, you would also port your TB, upper intake, heads, and run headers with a 3 angle valve job. But all of that is not necessary. Just your intake will improve flow and volumetric efficiency. I would ported my heads, but there was no reason to remove them and I needed my truck back for the camping trip this week end.
 


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94Gexplorer

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ill have to try this on my spare intake
 




Spdrcer34

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Nicely done....Looks Good!

Ryan
 




9blackex1

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Fantastic Write up. being a performance science junkie I'm glad you mentioned the golf ball comparison. exhaust can be polished through and through all the way out to the tail pipe, but intake needs to have some turbulent flow to properly mix and vaporize the fuel. Great write up really made a complicated machine shop job something a techie can do in his garage over a weekend.
 




Spdrcer34

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9blackex1...On a Direct Port Injected Engine, the intake can be polished to a smooth finish. Only on TBI or Carbed engines do you need to leave a little roughness on the intake tract, to prevent puddling of fuel as it makes its way to the cylinder.

Ryan
 




9blackex1

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I stand corrected, now that i think back to the conversation i was having when we where discussing that we where talking about a typical Small block 350 obviously with the carb. on a side note "puddling of fuel" was the phrase i couldn't think of when i posted the First reply, dont know why either ha ha
 




Spdrcer34

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Quite a bit more material can be removed from around the injector boss. Removal of the injector will allow you to measure exactly how much more you can remove. Leave about .100-.125 there.

Ryan
 




tweakedlogic

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Quite a bit more material can be removed from around the injector boss. Removal of the injector will allow you to measure exactly how much more you can remove. Leave about .100-.125 there.

Ryan

True. There is a lot of material around the injector. For my porposes i chose not to since I'm not porting the heads at this time. Perhaps when i build the new heads i will.

I can say that throttle response and pulling power are improved from this mod. I'm running 31s with stock gears (5 speed)and now i'm thinking I don't need to regear until I fit the 33s. I can't give fuel economy numbers because my fuel gauge doesn't work and the speedo is off anyway.
i am very happy with the mod. I have also noticed it running cooler. I can't say that the mod had anything to do with this difinativly, since I was chasing a coolant leak. but it is definatly running cooler than the last 5 years I ahve had the truck.

I know it will improve further when i finish the upper manifold. I wish there was a dyno near me so i could get some numbers. Oh well. Maybe the wife is ready to move this year.
 




jd4242

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Quite a bit more material can be removed from around the injector boss. Removal of the injector will allow you to measure exactly how much more you can remove. Leave about .100-.125 there.

Ryan

when i had mine done there was all most nothing left of the injectors boss walls and all so he had to bust the sides out off a couple of the runners to make them more straight and get them to flow better.there was a TON of materiel that was removed from the lower intake and the harsh 90' bend into and out of the head ports.i had my heads done first with stock valves and 410cam,then i had my lower and upper intake done later on and i DEFINITELY felt a BIG difference,but also went to SI portflow valves and 422.
 




baggedexploder

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Awesome thread, I'm going to go port mine right now lol.
 




Joe Dirt

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Nice write-up tweaked!

Just a question- do you like the rolls better than flap-wheels? I've always used flap wheels and haven't tried these before...

Flap wheels for those not familiar:

546017.jpg


This intake was on my Mustang, done with flap wheels, but the rolls seem like they might be more flexible:

DSCF0636.jpg
 




RustySJohnson

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Holy time consuming

I have a whole new respect for those who do this for a living. Wow, 8 hours into the sanding and I only have 4 1/2 ports complete.




I hope it's worth it. Does it look right? Anyone..........?
 

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jd4242

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I have a whole new respect for those who do this for a living. Wow, 8 hours into the sanding and I only have 4 1/2 ports complete.




I hope it's worth it. Does it look right? Anyone..........?

I would trace what ever lower gaskets you are using on there so you know how large to port them.looks good;)
 




explorinitup

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Nice write-up tweaked!

Just a question- do you like the rolls better than flap-wheels? I've always used flap wheels and haven't tried these before...

Flap wheels for those not familiar:

546017.jpg


This intake was on my Mustang, done with flap wheels, but the rolls seem like they might be more flexible:

DSCF0636.jpg

where did you find thoes flap wheels. i used the rollers but i would like to try out these wheels??
 




jd4242

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where did you find thoes flap wheels. i used the rollers but i would like to try out these wheels??

Ii used the flap wheels on my dremel when i did all my sc porting.i got my at granger
 




wood1

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Cool write up. Did the heads/intakes in my stang back in the day. Very time consuming indeed. I polished the intake to a mirror finish (more of less) as it flows just air. I left a rougher finish in the intake port of the head to help with fuel atomization and a mirror finish again in the exhaust port. That with a cam, headers etc it dyno'd at an honest HP per cube. Other than the fact that it would barely idle I was pretty happy with the result ha ha...
 




RustySJohnson

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16 hours and still not finished

I've broke 3 Mandrels and used almost 2 boxes of 80-grit sanding rollers from Harbor Freight so far. Removed roughly a pound of Aluminum.

The entire weekend and one evening's ate up. Going at it again tonight with the finishing touches and making them all match.

This is a chore, I don't care if I ever do this again.

I don't see those flap-wheels working out well, I don't know how you'd get the corners or some of the tight spaces with those.
 

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jd4242

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I've broke 3 Mandrels and used almost 2 boxes of 80-grit sanding rollers from Harbor Freight so far. Removed roughly a pound of Aluminum.

The entire weekend and one evening's ate up. Going at it again tonight with the finishing touches and making them all match.

This is a chore, I don't care if I ever do this again.

I don't see those flap-wheels working out well, I don't know how you'd get the corners or some of the tight spaces with those.

For my sc stuff i used burr bits first then the flap wheels.burr bits to remove material and sand paper bits to smooth/polish.there shouldn't be any real tight spots or sharp corners.you can also shape them into triangles and they will get into tighter spaces.looking good tho.
 


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Tnashua

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I Keep forgetting to post picts / ask questions on this matter... I ported the heads and need to port the lower intake manifold. I have it marked out to "port match" it, but haven't started yet... I would like to remove more from around the injector bosses than the pictures show, but wanted to know if anyone has done that? I would taper it so that there is about an 1/8 or 3/16" left at the head side, while it retains more of the intrusion further up... Thoughts?
I intend to use my long reach carbides to get started, moving to the short ones for the outer edges, followed by the 80 grit rolls & then perhaps the 120... Since the fuel isn't introduced until the end of the intake it should be alright to polish it, but as most of the previous posters realize- this is already a super long endeavor & I honestly doubt that the additional polishing will yield enough of a difference to warrant the extra time...
I'll try to get my act together & get this stuff done soon (hopefully remembering to snap some photos along the way). Please let me know about the injector boss- anyone have pictures of their heavily ported lower?
 




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