15 replies to this topic

[benspickup2011]

Hello, ive got a few standard1275 heads lying around. one of whick ive smoothed all the sharp castings off in the ports and polished all the casting smooth. Is there a noticable difference when driving the car once this is done or is it a wast of time. Anyone done it themselfs and wished they'd just gone down the pub instead? Cheers Ben

Edited by benspickup2011, 09 February 2011 - 07:19 PM.

[Big_Adam]

Polishing is seen as fairly pointless, getting rid of BIG lumps and generally opening up the ports isn't.

I'd suggest picking up David Vizard's How to Tune the A-Series engine and giving a good look to the cylinder head chapters. Much you will learn from them.

[MRA]

smoothing rather than polishing the inlet & exhaust tracts

However polishing the chambers is worthwhile as it presents a smaller surface area for the heat to escape, the heat which is a form of energy is better converted in to Potential / Kinetic energy to drive your
pistons down

However does it outway the benefits of going down the pub ?

Edited by mra-minis.co.uk, 09 February 2011 - 07:56 PM.

[AndyMiniMad.]

Buy Mr Vizard's yellow bible, take it down the pub and dont leave untill you have read and understood the chapters on cylinder head mods.....Actually thats not a bad idea!!!!!Wheres me glasses.....

[bmcecosse]

Good work can be done - especially in the valve throats and generally widening the throats. Vizard is indeed the best source of information. Take care to protect your lungs when doing the work - use an old vac to take away the dust - and wear a decent mask.

[MRA]

Spot on info from above, the dust, just in case you want to run the risk and "take a chance" will have carbon which I am sure we don't need to tell you is a carciogenic ...... cancer bearing by product

Don't take the chance with your health make sure you have the correct mask and DOn't work in a confined space.

[liirge]

Spot on info from above, the dust, just in case you want to run the risk and "take a chance" will have carbon which I am sure we don't need to tell you is a carciogenic ...... cancer bearing by product

Don't take the chance with your health make sure you have the correct mask and DOn't work in a confined space.

Urrgh, carbon itself is NOT carcinogenic, otherwise everything (nearly) we touch would be such, think about it CO2 a form of carbon is a natural product of the air we breathe and an output from respiration.
Just mentioned that as to not miss lead people (look at the top of the page, bit in that pinky colour) but i do realise it is off topic

Edited by liirge, 09 February 2011 - 11:01 PM.

[MRA]

You are right.... especially as we are carbon based lifeforms

Ok so please enlighten us with your knowledge

[liirge]

You would wear a mask to stop small metal particulates entering your lungs and damaging the sensitive tissue in you Alveoli.

Edited by liirge, 09 February 2011 - 11:15 PM.

[MRA]

Waht about all the nasty soot though is that not also dangerous ?

[liirge]

Soot is dangerous (Well sort of, but in basic terms yes, and stay away where possible), but you wouldn't get that from this job..

Edited by liirge, 09 February 2011 - 11:19 PM.

[Cooperman]

What you get if you don't use a mask is big, black 'grollies' up your nose and a very dirty handkerchief!
It's a general case that the first bit of work you do on a standard head will make a big difference, but once the main items are sorted - the smoothing out of the 'short-side radius', removal of the valve-guide boss intrusions, de-masking the inlet and exhaust valves and cleaning up the casting steps around the valve seats - it's a lot more work to get a further small improvement.

[bmcecosse]

It's not so much the 'carbon' that would be carcinogenic (although undoubtedly unpleasant) - but the various hydrocarbons that will be mixed up in it from the combustion processes. Best avoided.

[smileytony]

Ok so I had a conversation with someone once (he's from the hot-rod community) who said polishing was pointless. He said the same RE getting lumps and bumps. However he was of the opinion that my 'roughing' up the inlet surfaces it caused better 'mixing' of fuel and air...just thought I'd mention!

[MRA]

It used to be common practice to polish the inlet and exhaust tracts, these need to have a roughness, that promotes a tubulent boundary layer to the main laminar flow of the fuel/air mix and the exhaust gases, so yes pointless, however polishing the combustion chamber is effective and raises the efficiency of the engine.