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MG Midget and Sprite Technical - Valve Guides

My 69 Sprite appears to have bad valve guides. I've determined this (assuming correct diagnosis!) with a vacuum gauge. The engine is freshly rebuilt with one season (8000 miles) on it. It has been using a bit more oil than I'd like and has some blowby. The compression is good; cold and hot; with or without added oil to the cylinders. But the vacuum guage fluctuates from 11-16 at idle.
The head was redone with hardened valves and works fine with the exception of the valve guide leaks. How hard is it to put it valve guides? Can I do it myself? What should be replaced on the head?

Bruce 'ready for a winter project' Hamper
'69 warp speed blue sprite
'59 in pieces Bugeye
B C Hamper

valve guids have to be pressed in place an then reamed to size not realy a job for the diy enthousiast

you say it has been rebuilt
what has been done?

you say the head had hardened valves?
i assume you mean hardend valve seats?
it seems strange to me that a good machine shop would not check the guides as well

it may just be bad valve stem seals
what type did you use the tophats or the ring type?
Onno Könemann

Hey Bruce,

I got to back Onno on this one....Id look at worn or cheapo valve seals....you want the (?Vitro brand???,)

It could be possiable that one or more slipped off...is it briefly burning oil at start up after a good 30 minunte minume to overnight sit still....That would be a good indication

DID you use the brass valve guilds?

If it is valve guilds, hold Up a month or So and Ill come up and we can do a vizard port on your head (there a big ol soft ball)

BTW...DID you place at the St. Louis show?

Prop
Prop

I just looked up the original receipt for the cylinder head work. I had it done in June 06 and didn't get around to using the head until the next year. Here's what was done:
Valve job - clean,check, grind valves and seats
assemble head with new valve seals
resurface head
install valve seats - exhaust

The machinist used the existing valves, springs, etc. Said they looked ok.
I'm going to take it off this winter to port and polish anyway. So this would be a good time for any replacements/upgrades.

And Prop - Here's the results of the St. Louis show! I placed second in the midget/Sprite catagory - Bugeye through 1974 chrome bumper Midgets. It's a tough crowd with a number of very nice examples.
I just came back from the Memphis Eurofest car show and placed FIRST in the Sprite-Midget category. - An even tougher crowd with all years of Sprites-Midgets from 1958-1980. I was pleasantly surprised in Memphis since a number of fine Bugeyes were in the group. Perhaps my 'war stories' of the drive with my wife and I from St. Louis gathered the sympathy vote! In fact, we had a great trip and covered the 300 miles without any problems----unless you really wanted to hear the stereo or carry on a conversation....Oh the joys of a 69 Sprite!

Bruce
B C Hamper

if it is a proper machine shop than the only thing left is the valve stem seals

get the good (viton)top hat seals (as used in the late mini's)and put them on in and exhaust valves
Onno Könemann

This thread was discussed between 08/10/2009 and 09/10/2009

MG Midget and Sprite Technical index

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