Race Engine Forum UK

Guy,
I am finding out that my hand filed ports get better results than die ground ones. I think that this is because its impossible to produce 'high frequency' features on the the curvature with files - where as it is very easy to end up with little peaks and troughs and 'roughness' with the die grinder.

Given that this is a highly laborious task, I was just wondering if you knew of any machinery that could reduce the burden? I'm thinking of a reciprocating file system or similar. There are systems out there but all the ones I've found look too bulky to use in a port!

Thanks
Iain McL

Just my take but i think thats going to prove impractical really.

I use Guys suggested Metabo die Grinder with integral speed control with the Metabo flexishaft and its by far and away the best/easiest/fastest method ive used thus far.
If you use moderate pressure and dont run the grinder too fast ( i usually go about 7000rpms-minimum speed setting) and keep the burr in motion it cuts nice and smoothly.
Using ATA bands and the split fork deburrer ensures you get a uniform finish that immediately shows up any surface irregularities, not that youll get very many if you use the same tools and methods as Guy.

Sorry Iain,

I have no knowledge of a suitable powered tool for that.

G

Many thanks chaps.

I'll look into the Metabo, but might have to 'put up and shut up' for now if its expensive.

Iain

Recipricating file and stone power tools are common in the mold/die making feild for polishing and contouring. Very costly though so I don't think it is a good way to go.

Google mold polishing stones and files. Many sources

Using a "flapper wheel" after grinding will take care of any shallow bumps as well. As others already stated, don't cut deep in the first round, but gradually work your way until you are close to where you want to be. Finish the last few tenth of a millimeter with more refined tools and flapper wheels.

:-) the Mk 1 finger can work wonders before a flapper finish

1NRO wrote::-) the Mk 1 finger can work wonders before a flapper finish

I think your finger will wear a lot quicker than the material the cylinder head is made of. ;)

:-) true, if there's no abrasive on it. SSR's are easily gouged/flat spotted with rotary tools, the defects show up straight away when the hands are used.

You can finish round ports with a small Flex_Hone, any diameter or grade you choose. *

Don't know why I didn't mention this before, I use them on tortuous inlet manifolds quite often. I oil up with Duck Oil or WD40 or even do them in the Jizer wash tank. Wear protective glasses, the oil splashes everywhere.

Here's the link to the UK agent, old friends of mine:

http://pacehigh.co.uk/category6767/flex-hone-reg.aspx

G

* be careful with Flex-Hones - you get 'hooked' on them and start finding all kinds of alternative applications to use them on..

Once again thanks everyone.

On the flapper wheels, does anyone know a good supplier in UK?

And on the flex hones guy, there is a worrying range of options available, I'm guessing that I choose one that is slightly bigger than the hole I'm working (controlling section is 24.6, so choose 1"?), but wouldn't really know how to choose the type of abrasive or grade!!

Its just an aluminium head and machines very easily.

Iain

You want just a modest degree of compression for the hones so get dead size or fractionally under/over. If they are bit small you just tilt them in operation to assure surface contact. They will scar the outer face as they go in if too big and just shed abrasive balls. Phone Pacehigh and ask for their advice on the honing.

Cromwell Tools are a good local source for flap wheels, or else MGB Supplies (see links)

G

I've ordered a 1" Flexhone.

So thats finishing sorted out, but something that I've been meaning to ask for ages is, how do you bore out controlling sections to a defined diameter?

Iain

By hand with burrs and abrasives, measuring as you go: you just need to practice and develop those skills.

For those who are not familiar there is a huge amount of step-by-step photography in my new book on this.

G

I appreciate the advice Guy.

My wife doesn't know it yet, but she's going to buy me the book for my birthday!

On the grinding front, I can't afford the Metabo, so am going for a cheapskate solution to augment my 3.2mm Dremel. Basically, i'm going to use my wood router with a flexi-shaft. This way I can use bigger burrs and flappers (based on 6mm shafts) to reduce the chance of troughs and peaks etc..