23 replies to this topic

[Bluenose]

Hi all,I'm the proud owner of a l reg 1994 Mayfair.upon starting it up you'd get some blue smoke,after researching the problem I put it down to the valve seals going.anyhow on taking the head off I realised that the valves would need replacing too.now here's the stupid bit!!!!I discarded the valves before measuring them,what a div!!I didn't realise there was quite so many different types.it's a 1275 cc engine and the head is a standard 12g940,it's also got 2043n or 2043h stamped by the thermostat housing.hope one of you can help

[Turbo Phil]

The standard valve sizes will be 33.3mm inlet & 29.4mm ex, triple groove retainers. A basic measure of the seats will tell you if bigger valves have been installed by somebody, the most common being to upgrade the inlet to a 35.7mm valve.

[Guess-Works.com]

or in English..... 1.15" exhaust and 1.3" inlet

http://www.theminifo...showtopic=19385

[icklemini]

to be honest, if you are buying new valves for it.. have a word with your local engine machine shop, they will probably be able to get them cheaper and will recut the valve seats to suit (something that you should do anyway!)

TTFN,
Dave

[bmcecosse]

Fit new valve guides if buying new valves - I'm surprised they ALL need renewing. Im also surprised you have lost the valves - I don't think I have EVER thrown away a valve - got a box full of them !! And -don't be surprised if this doesn't sort the oil/blue smoke problem....... It will be oil coming up past the piston rings.

Edited by bmcecosse, 12 January 2011 - 09:07 PM.

[Bluenose]

Thanks for the quick replies.but it seems that my query has solved itself.i found the valves :lol:they had been put somewhere safe,(you know that safe place you put things and never find them again)well i did yipee.what an incompetent fool eh?

icklemini:i live miles from anywhere so going to a engine machine shop sadly isnt a option.its 13 miles to the nearest supermarket.

bmcecosse;no offence but i hope your wrong

[bmcecosse]

Still think you should fit new guides anyway - fingers crossed for you...........

[Bluenose]

is fitting guides an easy job?looked on minispares and theyre not expensive so i think ill take your advice.

[bmcecosse]

You need a stepped drift to bang the new ones in without damage. May help to heat the head in an oven - and guides in the freezer. May cause some domestic anxiety.......

[Turbo Phil]

If fitting new guides, you will need to recut the seats.

[Bluenose]

Is a stepped drift known as something else?can't find one on the net anywhere.also reguarding the guides-it's the steel ones I want?as the bronze type ones are stated as being for competion use only??and last question for now.I seem to remember it saying on mini spares that the exhaust guides would need to be bored out??

[Turbo Phil]

The iron guides are standard, yes. This is all you need. When fitting new guides it is essential to ream them to the correct size, both inlet & exhaust to ensure no seizure occurs.
As I said you'll need to recut the seats to.

[Bluenose]

Thanks Phil.nothings ever as simple as it first seems is it.im going to use one of those lapping toolsyou attach to a drill fir the seats.how would I go about reaming the guides though?sorry but im a complete novice at this.

[MRA]

Dont use a reamer on a valve guide as it will be oversize..... look up the correct use of a reamer to confirm this

valve guides must be honed to size...... next people will be saying after a rebore don't forget to ream the bores

Also bashing them in is a sure way of damaging them, do you have a vice ? or a G clamp.... better still a press but definately not a hammer.

Cast iron guides can crack and bronze guides will deform

[bmcecosse]

Ideally - you would use a reamer..... However - the only problem with the guides is likely to be slight swelling where they are banged in - and in the past i have simply used a small scraper to remove any slight burr there. If the head is hot and the guides cold - very little banging is required anyway! I argue if the guides are properly made - the hole in the centre will be concentric with the outer diameter = no need to recut seats........ The valves will certainly meed to be ground in.

Edited by bmcecosse, 13 January 2011 - 07:09 PM.