paul_mcq
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| posted on 5/4/05 at 06:10 PM |
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polishing?
looking round screwfix came across this, would this be good for the polishing of a cylinder head?
800g. Use grey paste for cleaning and cutting metal prior to polishing. Use green paste in conjunction with a white cotton mop for polishing.
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wilkingj
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| posted on 5/4/05 at 06:54 PM |
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Shesto.co.uk
I used these people. Quick service, and even the mop that had sold out came about a week later..
Been reliable, and reasonable prices too.
1. The point of a journey is not to arrive.
2. Never take life seriously. Nobody gets out alive anyway.
Best Regards
Geoff
http://www.v8viento.co.uk
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NS Dev
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| posted on 5/4/05 at 06:55 PM |
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what polishing are you trying to do to the cylinderhead?
If you mean as in porting and polishing, the you just need abrasive drums for your die grinder, usually known as spira-bands, these give plenty of
polish for combustion chambers and ports.
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RogerM
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| posted on 5/4/05 at 07:24 PM |
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At the risk of being rude I'd have to say leave the head alone for now.
If you want to learn how to performance tune ports, valve seats and combustion chambers you need to start reading.
As you have an interest in the A-series engine you need to buy the following books, "How to modify the A-series Engine" "Performance
cylinder head modification" (I think) and "How to modify your Mini".
All these are available from the Mini specialists or mini based magazines, all are writen by the same man G.O.D. (as in Good Old Dazid ... as in David
Vizard). Once you have read those, twice, and everything makes sense then you are in a position to choose somebody to modify your head for you ......
You will need to do literally dozens of heads, ruining them all obviously before you will start to get good results.
The equipment needed is outlined well in the books and you can get your self properly tooled up for just the right side of £1000 and you should be
able to knock out a decent head in about 40 hours work! ..... That is why people like MED charge the best part of £1000 for a Miglia spec head.
Once you have done all that you will find that you have produced a head which is capable of producing about 90% of the power one of my heads can
produce, which in turn produces about 95% of the power a brilliant (a rare thing indeed) A-Series specialist's head gives.
In short, not worth the time, effort and money it will take to get something good.
I would never have set up just to do head modification, I bought the compressor, aire recievers, die grinders and other, volume measurement tools and
basic flow measurement equipment for other reasons. I have been doing A-Series heads for more than 10 years and am just about now getting special
results, then mainly with turbos because that is where most of my efforts have been focused.
If you want to learn to do head modifications all power to you please don't kid yourself that it is easy and for god sake don't modify the
only head you have got.
Get the books, get practicing.
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RogerM
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| posted on 5/4/05 at 07:25 PM |
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By the way, in common with most engines of that type, a high polish in the ports are the last thing you want!!! Read the books and you will find out
why.
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NS Dev
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| posted on 6/4/05 at 08:29 AM |
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A good argument put by Roger!
I think you have aimed a bit high on the cost side though Roger! it depends on how much DIY you can put in!
A DIY, pretty crappy but ok for comparison purposes flowbench can be done for £150 ish. My die grinder cost me £185 and the old as the hills black and
wrecker drill that I use for final finishing was free. The spira band holders and bands are not pricey and the carbide cutters are cheap if bought at
shows, carefully selected from the big bucket that usually has a few Garryson ones in it!. The grindstones for cast iron heads are pretty cheap as
well. get all my "consumable" stuff from cromwell industrial supplies as we have a very big account with them at work (steel rolling
mill)
My burette was liberated for free, and I now have a 3t arbor press that set me back £30, but I don't know if it will push guides out or not yet
until I get some punches turned up.
All in all, you need to spend a min of £250 to actually PORT a head, rather than just rub at it a bit!
Then comes the fact that it's no willy nilly job. I am currently on the lookout for a nice digital differential manometer as I think the plastic
tube and coloured water flowmeter manometer has met it's match with a coscast vauxhall head, any gains on this are not going to be very large,
looking at the standard state of the ports, which is amazingly good! (hand finished as std)
As Roger said, get several heads, the first one will not be right. Without a flowbench you will never know what "right" is anyway!
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paul_mcq
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| posted on 6/4/05 at 03:16 PM |
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cheers for all the help. the head on the engine all the ports are a bit on the rusty side, will it be best just to wire wool them and leave the rest
alone?
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NS Dev
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| posted on 6/4/05 at 04:49 PM |
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Basically yes.
Smmothing off any rough bits of casting never did any harm, but you are basically limited by available tools.
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