Porting Practice

[Paul Fithian]

Learning some new skills and practicing on a scorched cylinder before I carve up a modified 026 44mm. Any tips to suggest?

Intake first

 

[MemphisMechanic]

Stop slipping and gouging the cylinder wall, that would be a great start.

It also looks like you chamfered the port edge with a fairly rough burr and left it. I progress to a bit of sandpaper and/or a polishing wheel until the port edges look like wet chrome. Anything you can do to prolong piston / ring life is worth taking the time to do.

 

[MemphisMechanic]

Oh. Also…

Did you do the intake port from the inside with an angled handpiece? Do intake and exhaust from the outside, reaching in through that port.

I very much prefer that to working from inside the bore. You can’t really hit the cylinder wall, for one thing.

 

[Paul Fithian]

Great, thanks! I'll do that on the next stages.

 

[Mastermind]

Those double cut burrs are junk. Look up Buckeye Carbide SE-51NF on Ebay.

 

[Outback]

I don't know anything, but you might want to try drilling holes in it see how thick the metal is and how much you want to remove depending on what your doing. This is something I pulled out of a box from 8 or 10 years ago when I started playing cylinders so don't mock me too much.

 

[Mastermind]

This is a 044 jug.....but what I'm showing you here the sort of shape you're looking for. Symmetrical and neatly done. This is just a rough in of it as well.

 

[Paul Fithian]

Thanks Randy!

In addition to the Buckeye SE-51NF Egg shape burr, any other suggestions? I'll order direct from their web site.

Professional results require professional tools, right?

 

[Mastermind]

Thanks Randy!

In addition to the Buckeye SE-51NF Egg shape burr, any other suggestions? I'll order direct from their web site.

Professional results require professional tools, right?

Use your right angle with a diamond ball to do your bevels with. That gives you very good control. I use 80 grit emery cloth or a sanding cartridge to knock off the roughness of the burr....and a worn out 80 grit for finish. Don't get hung up on a shiny finish. A well shaped port, and a good bevel is more important.

 

[isaaccarlson]

I like single cut burrs. I use a cylinder radius end, taper/flame/tree radiusnd, and egg.

I use a diamond bit/file on my chamfers along with some fine wet/dry paper.

 

[isaaccarlson]

 

[Redfin]

If you are trying to use a template for durations, time it off the band not the base.

 

[drf256]

This is what an 024/026 intake port should look like IMHO. The outer is matched to the intake boot. I actually cut an oem one apart to allow me to see where it hits the snout. Common area for a lip, which will cause fuel to puddle while idling.

The roof is beveled and misshaped from the factory. Have to remember where the lower ring pin stays tucked. Safest to leave that corner of the roof rounded. IIRC, it’s on the PTO side.

 

[drf256]

Another tip, don’t hog everything out.

Think of a garden hose with the valve wide open. Nearly volume of water with or without a nozzle, but adding a nozzle makes it flow faster and further even if volume is slightly reduced. No nozzle makes it lazy, even with more flow.

I try not to make the opening in the plating for an intake port not bigger than 125% of the throttle plate area, sometimes even smaller. A big one may make more top end power, but throttle response becomes sluggish because of lack of speed.

 

[drf256]

Here’s an 044 intake, like Randy showed, for illustrative purposes only.

The 044 is good to show you the general shape because the intake tract is centered. Many jugs, like the 026, have that offset port with the flat side wall.

 

[Paul Fithian]

Beautiful work fellas, thanks for sharing. I’ll embrace these tips as I learn more.

I ordered a couple of Buckeye burrs and will update progress after having another go at it.

Learnings so far:
- Use the right tool
- Draw a line and grind to that
- Sharpen corners a bit more
- Grind from the outside where possible
- Sand a bit to smooth after grinding

 

[Paul Fithian]

Thanks Doc, those reference pictures of the intake you posted are a huge help and will be my guide. Do you have similar examples of your surgery for transfer and exhaust ports on an 026?

I want to make sure I get this right on a few scrap cylinders before I touch the one you shaved the base on.

 

[Ketchup]

Here’s a couple things to think about:

Measure carefully after your base and band cuts. Make sure your new port shapes won’t free port.

Set up a little station with nice overhead light and keep a small flashlight handy.

Cutter speed- sometimes you need a lot, sometimes not. The pedal is a tool.

Cut in sweeping strokes with careful start and follow-through. The ends of a stroke are usually where I make mistakes.

Keep your burrs from loading. Have a small vessel of WD40 or similar close by that you can dip the burr in frequently. This makes your cuts more consistent. And makes them last longer.

Don’t take the burr in or out of a port while it’s spinning.

Watch how your burr interacts with the plating. Cutting from behind the plating can lift and chip it.

Sometimes I’ll just place the burr in the port and move it as though I were cutting before I start. This helps me visualize angles and proper burr shape. I mostly do that for transfer uppers.

Blow the ports out frequently. Especially once you’re close to your lines.

Try to have your port shape smooth and nearly finished slightly before your lines. Correcting irregular edges or lumpy cuts is usually how I end up going past my targeted height.

Do the transfers when you’re fresh. Shaky hands or bleary eyes are a great start to a botched job.

If you haven’t, go read all the links in the Porting Threads sticky.

Have fun!

 

[Paul Fithian]

Thanks Ketchup, great advice that I will follow

JimBear kindly sent more practice material, an OEM 044 and AM 026 P/C’s, thanks James!

 

[drf256]

Beautiful work fellas, thanks for sharing. I’ll embrace these tips as I learn more.

I ordered a couple of Buckeye burrs and will update progress after having another go at it.

Learnings so far:
- Use the right tool
- Draw a line and grind to that
- Sharpen corners a bit more
- Grind from the outside where possible
- Sand a bit to smooth after grinding

Transfers and a pic of stock vs ported ex port.