MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG Midget and Sprite Technical - replacing valve guides at home

pulled my head (as you probably know) and this evening started removing the valves. seems the valve guides are pretty worn, there is a fair bit of wiggle. it would also explain my wobbly vacuum gauge readings at idle.

is replacing the guides doable at home? just batter them in with a hammer right?! :-D

your thoughts, tips and advice are always appreciated.

cheers
Malc.
Malcolm Le Chevalier

What engine? I've done A series guides a number of times but no experience with the 1500.
David Billington

yeah, 1500
Malcolm Le Chevalier

Id guess they have to be pressed into place

Get a qoute froma real shop...its cheap to do
1 Paper

Before you condemn them wobble each valve across the head direction then along the head if the wobble is greater across the head you have worn guides (rocker arm action causing wear).
Usually guides need reaming after fitting, however most replacement cast iron guides are a little big on the ID and only need the top and bottom tweaking from fitment damage.
Even if you replace guides at home you will most likely have to re cut the seats as guides are seldom perfectly down the middle and wear also occurs on the valve seats in use.
Peter
Peter Burgess Tuning

Thanks Peter, I had not considered that they might not be properly concentric once changed. By re-cutting do you mean actual re-cutting or just some thorough lapping of the valves?

Cheers.
Malcolm Le Chevalier

Here you go malc

Neeway valve cutting kits

http://www.cylinderheadsupply.com/neway-valve-seat-cutters.html?gclid=Cj0KEQiAhNnCBRCqkP6bvOjz_IwBEiQAMn_TMRWdkm-wLaK9Rv251HrsRn6gn_b3oKUBhyKkwARmcDQaAjCH8P8HAQ


Prop
1 Paper

I am as keen to do as much as I can at home but there is also sense in paying an expert on occasions, to me this is one of those jobs.
just my thoughts
P Bentley

Yeah, I like to try and do everything myself, much more satisfying, much better learning experience and only myself to blame if it goes wrong. But yes, it's maybe something I need to concede defeat on.

I might buy some guides anyway (only ~£20) then once I can compare the new guides to the old, make a decision.

Cheers,
Malc.
Malcolm Le Chevalier

Measuring your new guides against the valve stems will be deceiving. The ID of the guides will change when installed. I use to moonlight at an engine shop specifically doing cylinder head work & the number of mistakes I had to fix by well meaning but uninformed customers was amazing. It looks simple, it is not. I admire wanting to do it yourself but this is one of those areas where you could be penny-wise & pound-foolish. I also know that we charged more to fix customers' mistakes since we usually had to work harder to get a proper result.
s1

Malc.

Let me know how forging your own valves works out or casting your own pistons

Haha

Yeah i know what you mean but ther is only so much you can do unless you got a full $million dollar shop plus staff

I did my own porting and push rod hole enlargment and all the design work with ordering rhe parts i was very stoked about that...but i left everyrhing else to the pros...and im glad i did

Cly heads are very complex living species and live real lives

Orginally i wanted to cast my own cly head but it wasnt long before i realized that was never in the cards...it sure was fun to study and think about it.

Prop
1 Paper

Malcolm,

Where are you in Gloucestershire as I have a home made set of 3 angle valve seat cutters that have done a quite few A series heads and the odd FIAT twin cam head. I looked up the valve stem size for the 1500 and it is about .310" so quite close to that of the FIAT valve stem IIRC so I could likely reduce that a bit if required. I you do fit your own I would try using a press rather than hammering them in even if you used a cheap Chinese arbor press as it helps prevent impact damage on the ends of the guides. I've always fitted my own guides to my A series heads and never found a need to ream them but my experience is negligible compared to Peter Burgess's and I haven't fitted new guides for over 20 years so can't comment on current quality.
David Billington

Hi David
We use a pilot which rotates with the cutter when using our MIRA seat cutter, this means we have to ream the guides until the pilot fits. Minimum is tweak the top and bottom of the guide, usual is the whole guide needs reaming as the ID is squeezed when the guide is fitted. If it doesnt need reaming when using a go-no gauge it means the guide was probably oversized to start with. Using the valves to check size of guide ID is not very good as it just shows there is a clearance not what clearance.
Peter
Peter Burgess Tuning

Awww, come on Prop! You are getting wussy in your old age! What about home forged pistons? A block of soft aloominum and a sledge hammer?!

A quick calc of the thermal expansions and I reckon getting the guides in would be easy if I baked the head and froze the guides. Then a reamer is less than a tenner, some valve grinding past and a stick another fiver, the food to power me another £10... :-)

I am in Bishops Cleeve David. So only just in Gloucestershire.

Cheers,
Malc.
Malcolm Le Chevalier

Malc

There was a really good movie about 10 years ago with Anthony Hopkins as a old salty motor cycle racer racing his triumph at the boonville salt flats in the usa back in the 50s

But at the beginning of the film ot shows him in great detail forging his own pistons out of his garden shed...quite interesting id love to try it just to see if it can actually be done

I cant think of the name of the film at the moment... but it was really well done ..if steven is lurking about... he will know the film title

Prop
1 Paper

yeah, the worlds fastest Indian. I enjoyed that film.
Malcolm Le Chevalier

And, Prop, the title was Worlds Fastest Indian because the motorcycle was an Indian rather than a Triumph. I liked the movie too. Remember the scene in the motel room where he is filling the dry rot cracks in the tires with black shoe polish?

Charley
C R Huff

There is some good stuff on you tube about Burt Munro including some actual footage and a documentary very similar to the film. I think one of his records still stands despite many attempts to beat it.

Rob
Rob aka MG Moneypit

Charley

That is one of my favorite scenes....usking the shoe polish ...i think about the scene evertime im about to do something stupid to cut thur red tape

The look of horror on his friends face was just classic qnd then to double down and say so and so that heads the safty commitee will never notice was just the best as now the friends had a dilma to say something or not

Haha... i loved that scene.... i can so relate to that old guy i am him all the way

Thanks for the heads up everone on that the bike was an indian and not a triumph

Prop
1 Paper

And you coming from the U S of A too!
Peter
Peter Burgess Tuning

This thread was discussed between 17/12/2016 and 21/12/2016

MG Midget and Sprite Technical index

This thread is from the archives. Join the live MG Midget and Sprite Technical BBS now