Race Engine Forum UK

Porting advice required please.

I would like to have a straight path here - as you can see there is a step where the adapter plate meets
the manifold.

I have two ATI Garryson Carbide Burrs (1/2" + 3/8") but I want the walls of the manifold to be round
and all the same size whilst maintaining the taper - which I wont be able to do with the burrs?

Many thanks

hi Mitch,

Difficult to judge from the pictures: is the top of the manifold slightly wider than the adaptor bore?
If yes, then you will not gain much (anything?) by smoothing the arrowed section. I would just leave it as it is.

regards
Tom

As above, but a couple of other things.

If there's any "wobble" between the two, you need to dowel the two together in some fashion, or you'll get a step on re-assembly/disassembly anyway.

You don't say what shape the carbides are. You'll have a better chance with a longer profile one -- it's very easy to dig a trench with ball ones. You may, if the step is small, have better luck with a flapwheel, but take the speed of the die grinder down.

Thanks for the reply - it really means a lot to me.

There is a step where the plate meets the manifold - as it ends with a radiused? edge (arrowed)
Wont this step affect air flow?

As you feel with your finger starting at the entry of of the adapter plate its flat then dips down into a trench then the diameter is
smaller then the entry with a noticeable raised hump.

Entry of the adapter plate is 45mm and im using 45mm carbs - i know the chokes are smaller then 45mm but with my limited
knowledge it seems to me that it could flow a lot better.

Hopefully the image attached helps, my ideal solution is to get my friend to tig into the join in the bores
then port and fettle the area - in effect making a one piece unit.

The burrs are the teardrop shaped ones.

Thanks

Hope this image helps - i will get accurate dimensions when i have access to my tools.

The bores of the adapter plate are tapered (45mm entry / smaller bore as it meets manifold)
I will pin them to make sure they dont shift once fitted.
Thanks for your help with this.

I like your plan. Impossible to quantify the effect (without a flowbench) but I can't see that it can possibly do any harm.

No need to overcomplicate this.

No dowelling is needed. The influence of mismatch is frequently overstated and in this case it will be non-existent. The gian from modifying the OE manifold I can't quantify but it can't do any harm. In many cases I have tested a modest radius has no ill-effect on flow - many 16v heads have such a feature just inboard of the port face. The fact is the flow controlling section is simply the smallest diameter - wherever that is, and it is likely the exit region where the manifold joins the head.

If you want to modify follow the idea in the sketch - form a gradual taper shown by the red lines.

G

Thankyou everyone thats replied - and Guy this is just what I needed to know - the diagram is great and I will follow it.

May I ask what tools / measuring equipment to use to do the job properly?

I know from searching posts on this forum whats recommend for porting heads - burr / Ataband / Split fork
Is this what you would suggest to use as we want the walls to be straight.

All i have at the moment are the Garryson teardrop shaped burrs listed above and i made a split fork tool.


Many thanks and i plan to start a thread on my 130tc soon.

Carbide burrs - You'll really have to buy a few shapes and find out what you like best. Different shapes for different jobs! Ball-nosed, oval, flame get used the most here. I use 6mm shank mainly.

My preferred ones are Garryson and you can buy from MGB Supplies (see links):

http://www.atigarryson.co.uk/Catalog/Bu_Catalog.asp

Their 'aluminium cut' burrs don't get 'clogged-up' so can be used dry and they have the highest removal rate but they are very agressive and can run round the inside of the port making an awful mess if you don't keep your mind on the job.

Standard cut is a nice one but will need spray oil to stop the teeth getting clogged with alloy. The diamond & chip breaker ones are OK but same rule applies and they clog fastest of all esp dry and when worn develop a hopeless surface finish.

G

Many thanks - will post images as i progress.

Using the 1/2" Garryson Carbide Burr with lots of WD40 Resullted in this I then used strips of 60 grit sandpaper rolled like a drum around a slotted 13mm bolt in a drill - a crude Ataband but it worked and resulted in this -
its absolutely smooth and is a straight path with no steps or bumps: Its what I wanted to achieve so thanks to Guy and everyone that posted in reply to my original question. The only problem is - now the inlet manifold is lovely I notice the mismatch / step between the manifold and head.
So my plan is to rebuild a spare 130 cylinder head and continue to learn and apply what I learn to porting and preparing
the spare head - this will be in a new post when I have gathered the necessary parts - headgasket set, new valve guides,
3 angle seat cutter - and of course - everything else one may require.

I want the standard of preparation to be very high - of course - as well as being technically correct I want it to look good.

Nice job.

[quote="mitch strada"]Using the 1/2" Garryson Carbide Burr with lots of WD40

I use bees wax on aluminium with very pleasant results. My favorite is mesquite honey bees wax from Arizona, USA. Start cutting to get some heat in the burr and then turn off the die grinder. Dip the burr into the wax which will melt around the cutter. When you begin cutting the aroma of the honey still in the wax will be most enjoyable. The wax that is spun off the cutter will coat the port so you can continue cutting for quite a while.

Many thanks for the comments - I can report that the car goes like a rocket!

Re. Beeswax - I will certainly give it a try.

Bit quicker than twin 40s aren't they?!

G