Back firing

[easo]

G'day All, well just came back from taking the 'old girl' for a blocky. Come around the corner a she started to die, cough and boom.

Got her home, slowly, and took out the spark plugs. Found No 3 to be blacker than two black things. So I'm thinking that one of the valves is crusty.

Hey JohnE remember that valve removing tool?? The one the scrappys took?? Think I might need it now!!

Easo

[JohnE]

mate thats a bugger,
i know we should have put the bits we got out of the kombi into the back of the orange beast.
i have one but distance is a problem atm.
anyway mine is a made up one.
years ago when i did up my first motor ( a 250 ford) I needed one, the price of the valve spring compressors was a bit rich.
So I used an old sliding g clamp,with a couple of modifications and still have it today. used it on the ser 3 the other day to get out a burnt valve. I have used it one 5 motor rebuilds with no problems, the last one was the fergy tractor.
I'll take some photos for you, they are easy to make.

john

[JohnE]

"blacker than two black things' what does this mean, really black!!

ah the morning funnies,
just went out a took a photo or two

the old motor is on a block on the side of the shed with no concrete( just in case someone points out the dirt.)

here it is sitting on the block.

just to get dimensional size.

the measurements are 400mm long the top strap is 170mm and the web side to side is 1 1/2 inches .


http://i178.photobucket.com/albums/w248/JohnE_1/HomePhotos331.jpg


here it is inserted, the movable section round sits on the top of the valve
and the notch on the washers that sit on the springs

http://i178.photobucket.com/albums/w248/JohnE_1/HomePhotos332.jpg

all you do is slide it up to contact and screw the handle , pushes the washers down and the fiddly bit is getting the collets out, just like a bought one.


across the flat with a valve stem in the middle to show how much you cut out
http://i178.photobucket.com/albums/w248/JohnE_1/HomePhotos334.jpg


the top section sloped down so i had to cut it out for the valve to protrude.

http://i178.photobucket.com/albums/w248/JohnE_1/HomePhotos338.jpg


and jim was my uncle, this thing has performed flawlessly for years for me.even used it on the motorbike top end rebuild

cost was nothing.


john

ps just noticed the valve see the two large chunks out of it , really burnt out and it was no 1 cylinder

[easo]

Well I have taken the head apart, the vale is ok. So Ive re-set the timing.

Looking for my feeler guages now to check the clearances.

Easo

[JohnE]

good one mate,
not such a problem after all,
it could have been a fuel problem too, did you check the carby possibly the float level or maybe, backfiring maybe a leaking gasket.
over riching the mix and flooding it?? just a guess.


john

[easo]

Carby is in a desprat need for an overhaul. It makes a weezing, squaling sound at idol.

[JDNSW]

Carby is in a desprat need for an overhaul. It makes a weezing, squaling sound at idol.

These carburetters are a bit noisy at idle, helped by the quietness of the engine, but I suspect that the noise is mainly coming from a leaking, worn throttle spindle and bearings. This is a common problem with old carburetters of any type, and the Solex does not have as long a bearings as does the Zenith that replaced it.

And an intake air leak such as this is a prime suspect for backfiring. The problem is, you set the idle mixture, but next time the throttle closes, it is in not quite the same position due to the wear, and more air leaks in, giving too weak a mixture.

Could also be an air leak on either the gasket between the head and the manifold or carburetter and manifold. A squirt with WD-40 or similar in the suspect locations will help diagnosis - the light oil will temporarily block the air leak unless it is real bad - then it will give clouds of blue smoke from the exhaust.

John