Bought myself a wee project

Mattius

Mattius

Mattius

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18 Oct 2002
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Edinburgh
while the spitfire is in gettin the new gearbox shoe horned in i decided i needed another new project. So i picked up this for it.
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Its a spare cylinder head which has take me all day to clean up to this state. Im reading up about porting it. Anyone done this before?
the chambers are shockingly rough from the cast.
 
nooooooooooooooo dont do diy headworkd if you dont know what your doing


you'll loose power and make it undriveable.



leave it to the experts

most i would recommend is just to give it a decoke and match the ports using the gaskets and the manifolds.
 
im not doing major head work, just polishing the chambers and taking off the rough casting marks, then later it will be going away to be gas flowed and have the head skimmed to boost compression.

if you want pics there are here
http://www.mattinglis.com
 
Yep I did my 100E head and it makes a massive difference. Despite what sormicroft said on an oldschool head like that it does make a big difference. Grind down all of those rough casting flashes inside so they are flush and smooth off the walls of the ports. You want them smooth but not polished, because it uses a carburettor if you polish it the fuel forms droplets on the sides and upsets the mixture. Don't bother opening them up unless you're using bigger valves.

Get some old-style valve grinding paste and regrind the valve seats which will improve the sealing. The tool you use for this is like a stick with a sucker on the end and you spin the valve backwards and forwards in its seat. Put some new rubber valve guide seals on top in case it is letting any oil by and put a set of new standard valve springs on as the old ones will have softened a bit through use. You'll need a valve spring clamp to release the valve spring retainers which is a bit like a G-cramp with a forked end. Make sure you number the valves so they go back in the right holes.
 
I ported my own mini head, the best way to do it is with a dremmel or a small sanding drum in the drill. To start with though use a rotary file to remove 1-2mm around the port. Then swap to the drum sander and get it nice and round and smooth. To finnish up get a very fine sanding drum with some oil or wd40 and smooth it out. When you are removing thne majortity of the material keep the port as cylindrical as you can and then measure your inlet manifold and flare to top out to around this diameter. Thats how my dad said to do it when i did mine. Ohh also dont forget to smooth the throats of the port or it will not be as good as i could be. Take AGES grinding in the valves with loads of grinding paste this will ensure the best possible seal. Apart from that all i can say is take your time and remove the material tiny ammounts at a time measuring as you go, use a dial bore gauge to determine hw much more you need to take off and good luck, it takes a while maybe 6-7 hours so better off oing one port at a time.
 
sormicoft said:
nooooooooooooooo dont do diy headworkd if you dont know what your doing


you'll loose power and make it undriveable.



leave it to the experts

most i would recommend is just to give it a decoke and match the ports using the gaskets and the manifolds.
Click to expand...

What tosh.

Get the grinder out and have a go.

As Johnny and others have said, get rid of the casting flash and smooth up the ports.

PPC showed you how to build your own flow bench using an old vacuum a few months ago...

*n
 
im not gonna give flowing a shot, that is one thing i agree is best left to the experts.
finally got the head stripped bare, took me a while to get the valve guides out.
the basics im gonna do is clean up the casting marks, smooth the ports, polish exhaust ports, remove ridges inside the head, match the ports to the gasket.
then this head will be built up on the bench using all the latest trick bits and machined bits, like lightened rockers and shaped valves. so no need to number them or keep them in order.
then in the summer just before heading to the spa classic it will be switched over whilst im replacing the camshaft.
should give me plenty of oomph for the german autobahns.
 
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well im progressing slowly but surely but the polishing is a nightmare, i can't seem to get the grind marks out.

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Looks good to me, much better than it was out the box. Like I said you want smooth, not polished. Grinding marks will be fine. Only polish if it's fuel injected.
 
Mattius said:
well im progressing slowly but surely but the polishing is a nightmare, i can't seem to get the grind marks out.
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As Jonny says, don't even try. A polished finish is not what you should be aiming for unless it's to stick on your mantlepiece and admire. A ground finish will help keep fuel suspended in the air rather than forming drops on the port walls.

The port finish is also the least of your worries, the port shape is far, far more important to airflow. You also want to think about getting the valve seats cut with three angles to improve low lift flow. Going mad with the grinding paste to get a good seal just recesses the valve and makes the valve seat very wide, spoiling the air flow at small lifts, if the valve seats are very pitted they need cutting before grinding anyway.

huzeeee said:
I ported my own mini head, the best way to do it is with a dremmel or a small sanding drum in the drill.
Click to expand...

That's only the best way if you enjoy wasting hours of your time. The best tool is a die grinder with a carbide cutter or grindstone. Dremels are puny little toys in comparison.
 
yeah im getting the valve seats cut to serdi spec (tripple angle) also new guides, new valves (slightly larger) and having the head skimmed by 0.08" to boost the compression ratio slightly. im not meaning polishing i was meaning smooth out.
 
used powerfull degreaser, then wire brush in a drill and dremel to get all the rust and crud of it.

im using tungston carbide burrs to do the grinding work. unfortunatly im too cheap to buy a compressor or an electric die grinder so im having to use the dremel which is taking time.
 
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