295 Head - what's the benefit?

[stuart_k]

I keep toying with the idea of fitting a 295 head to my 1098 engine because I read it is a worthwhile improvement. But I do wonder what the actual benefit will be. Is there a noticeable improvement in umphh for the driver behind the wheel or just an improvement on rolling road figures to boast about?

And if by some miracle I win the lottery this evening is this head http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT
worth aspiring to or is it over engineered for a Moggie?

[linearaudio]

Fit a 940 head! Much better flowing, bigger valves, higher compression (~10:1) as standard fit to 1098 block without needing skimming to acheive it! Stronger head, more common/ cheaper, etc etc....

[stuart_k]

940 bolts straight on but it requires a bit of work to sink the valves, may need to change water pump depending on the bypass being present or not doesn't it? And didn't I read somewhere that a different rocker set may be needed? I don't want to have to do any work as I'm not sure I can do what is needed so any adjustments are going to have to be done at extra expense. If I can pick up a pre-skimmed 295 it will bolt straight on won't it?

Any way doesn't answer my question. Is there a tangible noticeable difference in power when using either of these heads?

[bmcecosse]

Yes - fitting a 295 head (after skimming to raise CR) will give additional power if fitted with a decent carb/manifold and exhaust manifold and system. The MG1100 was rated at 55 bhp against 48 for the normal 1098. The ebay head is stupidly expensive! It has been fitted with slightly larger (+4mm) exhaust valves, although the inlets are only very slightly larger (+1mm). The head has NOT been highly modified - the valve throat pockets are virtually unchanged - and the guides have not even been 'tapered' as they should be for best flow. He says no need for pockets - but I would be wary - those larger exhaust valves could clip the cylinder wall - especially on a standard bore 1098, and almost certainly on a 948. You will get far better result - for MUCH less money using a 12G940 head. You 'may' need to sink the exhaust valves into the head by 40 thou (but many find after taking the measurement that this is not necessary), you probably need to spend 2 minutes filling a little off the top flange of the water pump casting - and yes - you want the later sintered rockers of which many examples are always on ebay. Or - you can re-set your own 1098 rockers on the shaft so they act directly over the exaust valves - a 30 minute job that is actually quite satisfying to do properly! To benefit from either head you need an HIF 38 carb on an MG Metro alloy inlet - and a better exhaust manifold and system will help, but is not immediately necessary - it can be added later.

[stuart_k]

Thanks. Sounds like the best way forward is to find a half decent 940 and work from there. I think I'll try to source one and treat it as a long term project rather than doing anything this season. I can collect the other bits and pieces as time and funds allow that way.

Having never worked on a cylinder head before I am unfamiliar with the processes. How exactly do I sink the valves? Does it require machining in a shop or is it something that can be done on the kitchen table? For the benefit of my wife I'll just clarify when I say kitchen table I mean that metaphorically speaking

[bmcecosse]

Very definitely the kitchen table is the place - just sweep all that cooking stuff aside..................... at your own risk! IF the head needs the valves sinking - then yes - it needs machining. Mine took all of 10 minutes with a pillar drill and a 45 degree countersink. Any competent machine shop will do it for you - and it will certainly cost much less than having a 295 head skimmed. But - many have found there is enough clearance without doing the 'sinking' - so it's a case of measuring up and seeing what clearance you have. The valve lifts 320 thou (actually 318 - and then less the 15 thou gap = 303 thou) so if you have 320 thou between head of valve and surface of head - there's plenty of clearnce, because the gasket adds another 30 thou or so extra clearance. Don't pay a LOT for a 940 - I have paid as little as £10, but for some reason ( ) recently the value seems to have risen slightly! You should get a good one for £40 plus post of course - just keep checking ebay, and of course if you can get one near you without paying post - that's a good bonus!