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I am about to start my first porting job on a 1300GT head.

I'm thinking that mounted stones might be a bit more friendly than HSS burrs. I have obtained a flexible shaft and will be running it off an old variable speed router - sticking to fairly low speed in deference to the cheap flexible shaft

Can anyone advise a source of good quality coarse stones and sizes to obtain for porting work. Loads on Ebay but I imagine they will last no time. Should I completely rule out using Garryson burrs or might they be okay for metal shifting?

I have an Aldi dremel type copy which I will use for finishing with the small sanding belts, I am mainly looking for the best way that a first timer might shift bulk metal safely and efficiently.

Cheers

Jon

You'll be at it for weeks with stones, you need tungsten carbide burrs to remove a serious amount of metal. Plus you really need to be turning them above 10,000rpms.

The aldi dremel is a serious piece of kit. Much better than a dremel-dremel.

Long reach mini air die grinder is a good weapon for shifting meat. I would recommend a aldi one (with really expensive stones). Take your time and really do it like an artist would. Remember vizard's trick for not breaking into waterways.

It's all about the stones. You need a meaty machine for mega meat removal and a "pen" one for the art.

You should be able to get a superduper mega-head done on the cheap.

I tried making my own rimflow valves as well......fail.

I agree with Smithy, Carbide burrs are a MUCH better bet than Stones of any type. Using stones you will be there until doomsday.

This is the type of thing I use.

http://www.ebay.co.uk/itm/Tungsten-Carb ... 20ee4c2f2d

Not that I have done a head in years.

Yes, the stones "shine" and then it's game over.

I've just done my first ever using Summit Racing porting kit from ebay
with an air die grinder,very pleased with the result

Everyone will have their preference. I treat this like any other finishing operation, start with coarse cutters for heavy material removal, then progress to finer media for detail work.

The double-cut burrs Mark provided the link to are great for roughing. I assume the Summit kit that Coop12G295 referred to includes fine and coarse sanding drums and points for use on long mandrels. If so, they work very well for details. Remember that while you may wish to polish chambers, you don't want super shiny ports.

Wear a dusk mask or respirator regardless of which abrasive/cutting media you are working with. Remember that extended shank burrs and mandrels will want to walk out of the die grinder collet. Stop and tighten it frequently or you may create serious damage before you know you are loosing control.

I just got a die grinder from screwfix, £25 or so. Problem is it needs 2 compressors in tandem to keep up. But with a garryson burr shifts metal like you wouldn't believe, fantastic.

Oh, and I'm practising on a scrap 1000 head first to get a feel for it.

Cheers guys and thanks for that link Mark - just bought 3 of those burrs.

I've invested in an Evolution electric die grinder as well - my compressor is too small to run an air grinder.

I will post up some progress pics in due course

Jon

Btw, be careful when porting - it's easy to go way too far and remove too much metal. I learned porting two-stroke motorcycle barrels... and a few were definitely wasted!

Also, skip the Dremel - I highly recommend a quality rotary tool like the Foredom:

http://www.foredom.net/

I'm sure you will find the burrs great for shifting large amounts of material, but as other people have already pointed out the little twisty bits of abrasive paper are best for final polishing. I didn't make this clear in my last post.

The flexible drive grinders in the link above do look fantastic, but are probably a bit over the top unless you are planning on going into the head modifying business full time.

But then again Mark, you don't want polishing. That's soo 18th century on a Mini

Looks good though.

I'd say the polishing thing is academic. Realistically, you're going to have a dynamic equilibrium set up with stuff on the walls and stuff not on the walls. Polishing merely reduces the surface area. You're not going to get enough local turbulence to take stuff off the walls with that degree of "roughness".

Besides, when you are roaring along, there will be a net fuel in = fuel out with some being resident on the ports.

I don't imagine a dyno would show much difference. If it did, I imagine it would be miniscule.

I use die grinders occasionally for my work and am experienced with them for sculpting. Just a word of warning, hold on tight and concentrate, don't get complacent as when they go bang its not good at all. I had one a couple of years ago (rupes 30,000rpm) get stuck when I lost concentration and it took out the collet as well as the carbide burr, it went off like a grenade and all I had left was a broken stump in the neck of the machine, I was lucky nothing hit me in the face. Also not good if you accidentally let go when the burr bends and its running around the floor. Make sure you always have somewhere for the waste material to go, don't plough it in all in one go as it will jam. I mostly use pneumatic now as they stall easier.

Cheers for all the comments, most helpful

The grinder has turned up and looks to be a very good bit of kit if a bit on the heavy side. What impressed me was the accessory kit - 4 burrs, 4 flapwheels and a bunch of cutting discs - all Garryson branded. I probably need not have bought the burrs highlighted by Mark (I assumed the bundled accessories would be rubbish) but they will come in handy for the next job. £107 for the grinder and accessories delivered

Vizard book now borrowed from the library, Dewalt safety glasses - check, dust masks - check, dust extraction 'system' - check.. so now off to the garage

Updates to follow.

Jon

Good luck, let us know how you go.

Remember take it steady & let the cutters do the work.

To all of you who are having a go at this.......well done!
I sub this job out as I would never have the guts to try it

had a had a go with some burrs, and it does remove metal well. be carful when going through the valve hole not to hit the seats.

i had a play for 15 minutes, and then decided to send it out to someone who knows what and where to remove from to gain the best out the head.

i ended up taking it to brett sims, in new milton,
when i showed him the head i had ground too much on the inlet port and worn through into the push rod hole,so he had to be sleeved,

when i got it back it looked amazing, and very happy to pay the money for the amount of time, skill and know how, worth every penny.

but nothing wrong having a play yourself, i am all for people who wants to learn skills , i like to do it,

Brett is indeed a real artist.

I have cut my own heads & in general they have worked fine. However I have not done one for some years now & consider the money spent well worth it.