Thread: 1955 2l spreadbore blow by or valve seals

I have a 2l with a Weber 34t carbie.

Jet open 1 1/2 turns...

Tried 2 turns and slightly better acceleration

Read post where other is open 2 1/2 turns? Big difference.

My exhaust is sooty black indicating rich mixture and plugs dry with black/brown colouring.

Do I keep opening it? And does bigger jet opening transpose to increased fuel useage as you would suspect.

(Consumption is within range- almost twice that of the Tdi)

Originally Posted by Brad110

Symptoms

Slight blue smoke from rocker vent

Oil (not smoke) being thrown out of oil filler tube at high revs

Little/ occasional black smoke from exhaust on acceleration

Slight puff on startup (could be fuel?)

Good engine braking and power.

Cannot feel any pressure at rocker cover

Exhaust pipe dry but sooty



What is likely problem valve seals or blowby?

Is there a symptom to detect if its the valve seals? Or do we look at this once we discount blowby with a wet/dry compression test? Or is a leak down test useful?

That should be enough.

High probability that the inlet valve stem seals have gone hard, so replace those first and then with some long distance runs with a couple of quick oil changes with a mild detergent oil could free up stuck rings.
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Originally Posted by Brad110

I have a 2l with a Weber 34t carbie.

Jet open 1 1/2 turns...

Tried 2 turns and slightly better acceleration

Read post where other is open 2 1/2 turns? Big difference.

My exhaust is sooty black indicating rich mixture and plugs dry with black/brown colouring.

Do I keep opening it? And does bigger jet opening transpose to increased fuel useage as you would suspect.

(Consumption is within range- almost twice that of the Tdi)

Sooty = rich setting, there is more power is produced up to the point where it is too rich and then the power drops off quickly after that.

This is all wrong, for a properly tuned engine shouldn't be running rich, look for a light brown - grey deposit on the spark plug ends as it is a good indication of the correct air fuel balance .
The Solex carburettors were nicely tuned for those 2 litre engines, those carby's were well set up for slow running but because of that they didn't have a lot of top end performance as a result.

.

Originally Posted by Brad110

Symptoms

Slight blue smoke from rocker vent blue smoke is burning oil

Oil (not smoke) being thrown out of oil filler tube at high revs Quite normal; means the rockers are getting lubricated properly.

Little/ occasional black smoke from exhaust on acceleration Rich mixture; check that the choke butterfly is fully retracted i.e. no sticking choke cable.

Slight puff on startup (could be fuel?) Be more concerned if this happens with a hot engine.

Good engine braking and power.

Cannot feel any pressure at rocker cover A good sign but not necessarily conclusive.

Exhaust pipe dry but sooty You are correct that the mixture is rich.



What is likely problem valve seals or blowby?

Is there a symptom to detect if its the valve seals? Or do we look at this once we discount blowby with a wet/dry compression test? Or is a leak down test useful?

1. Do a compression test first; dry then wet on a hot engine with the throttle wide open and the coil disconnected. Record the results.
2.If the compression gets better in the wet-test, the rings are either stuck or worn out.
3. If the compression is good on both tests, it points to worn valve seals and perhaps valve guides.
4. Road test the car with a friend following behind; when you let you foot off the throttle on the over-run, a puff of blue smoke will indicate that the oil is getting in through the valve guides. No puff of blue, probably means the oil is getting past the rings.
Before pulling the engine to pieces try an oil-flush-treatment for the recommended time; Nulon and Cost Effective Maintenance make good ones that will free stuck rings.

If the valves are the suspects remove the head and investigate.

I don't know enough about the Solex but it may be more than mixture setting, so do a search for carburettor information on servicing and over-hauling; Mike from Gippsland has posted lots of useful info. over the years,

Cheers Charlie

PS Is the ignition system in top condition? Look for a fat, bright-blue spark at each plug; a yellow spark would help to explain unburnt fuel as well.

was in the same situation...and although no solution ,a lot of my blow by / sooty exhaust was only an issue during winter {condensation and a stored engine?} seemed to pick up a lot during the heat.

The valve guides are an hour job and easy to get{if uve had the thermostat housing off before.....} and you can touch up the valve seats while the heads off.

Another issue i had was buggered ht leads ,it ran but was quite changeable smoke/tune wise day by day
good luck
mark

Originally Posted by chazza

1.Mike from Gippsland has posted lots of useful info. over the years,

.

Thanks Charlie. I almost lost my sanity trying to fix the rich running problem . The only thing that worked was changing the main air bleed jet to a larger size ( the jet you see on top of the emulsifying tube , it's easy to see and remove it ) . The factory did this mod to the 32 when the spread bore motor came out ( as seen in the official solex notes ) , this may indicate that the earlier cars had a rich running condition . I now have a brown spark plug , not sooty black YEAH

I posted 2 topics together but it seems that I have things to go on.

I wasn't clear but I have a Weber 34ct. The plugs are a brown and exhaust sooty black which at a lean opening seems to contradict.

Didn't say but I have electronic ignition and new dizzy, rotar, cap and leads.

I also didn't mention that the car had sat for a long time prior to me purchasing it.

Flush and oil with detergent seems a goo idea. I was planning on taking sump pan off after long run ti inspect for sludge.

What oil with detergent is advisable. I only use 20/ 50 usually?

I think all engine oils have detergent in them now.

It is a good idea to clean the sump first. Use one of the specialised cleaners so that the carbon on the rings can be dissolved; and the engine will have to get nice and warm, whilst being driven on the road to make it worthwhile.

Have a look here Cost Effective Maintenance have a good read of their website and the testimonials as well. The fuel treatment transformed my petrol Disco

Cheers Charlie