Port and Polishing cast iron

[DougsfastZ]

Going to porting my stock downpipe elbow in the Buick soon and need some info or porting and polishing? I do have an air compressor but no die grinder, the problem is, the air compressor is small (15 gallon) and I'm afraid I won't have enough air. I do have a dremel but not sure what bits to buy? I heard double cut carbide burs should do the trick, but how long will they last? Is there any other bits I need? For polishing should I use 120 grit flapper wheel? I can't seem to find any of these bits locally.

Any help would be appreciated.

Doug D

 

[UNGN]

I get mine at work, but here is a place on the web:

http://www.american-carbide.com/default.aspx

If you let the burr do the cutting (and not use pressure), a dremel will have no problem doing the material removal. Were it has problems is polishing large areas that require larger tools, more pressure than a dremel can take.

Not "polishing" the elbow will mean it will rust sooner, but polishing doesn't improve the flow as much as getting the shape right. The shape can easily be done with a dremel and Carbide burrs.

If you don't abuse it, 2 burrs can do a pair of heads.

 

[Nashty]

Go to a local tool supply place, they'll have something for you reasonably priced. Get a flame tip (the shape, not a heat treat) carbide single flute cutter. Only get one with a mandrel as long as you need.

If you're planning on cutting aluminum ever with it, then get a double flute cut one. They let go of the shavings better.

Just imagine a thick liquid is flowing out of the passage you're porting and visually try to make it flow out easier.

I port all my own stuff now, heads, intake, exhaust... It's not difficult but it is CHEAP, my kinda work.

 

[DougsfastZ]

Thanks guys.

The website above shows 1/4" shanks, will that fit my dremel? I only thought dremels did 1/8"?

Is single or double cut good for cast iron?

Doug D

 

[UNGN]

Thanks guys.

The website above shows 1/4" shanks, will that fit my dremel? I only thought dremels did 1/8"?

Is single or double cut good for cast iron?

Doug D

They have 1/8" shanks, too. You just have to look for them.

A 1/4" diameter burr with a 1/8" shank works pretty good in a Dremel.

Single cut will cut better than a double cut burr, but the shavings will be little micro needles that stick in your skin and hurt like hell (until they rust away). Double cut shavings are more like a cornflake. You can swim in them and not scream in agony.

 

[Nashty]

10-4 to the agony part. WEAR PROTECTION !!

A dremel will be slow and a bit more uneven in my experience (I have done both, now the dremel collects dust).

Your little air compressor will work but give it some rest, don't buzz away for an hour while your compressor melts down.