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reading spark plugs


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Hi,

 

me and a friend are back from the European TR Meeting.

 

We don't know what's the problem with his engine,

spark plug 1 and 2 look strange, they are NGK BP6HS on a TR4,

last 200 miles before this photo was mainly highway.

 

 

photo deleted because of limited data base at the forum

Any idea? I'm using Bosch WR 78 on my TR4A, they are OK.

 

Ciao Marco

Edited by Z320
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Hi Marco

Try this link Marco how-do-i-read-a-spark-plug

Paul

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Hi Paul,

 

thank you, according to this link ist seem to be a oil problem from the valves guides or from the oil controll ring?

What to check first? Is there a possibility to find out with little effort.

 

What we also see are not only deposits on spark plug #1 and #2 but also "withe balls" on the surface,

mainly on #1 an #2, but also on #3 and #4, better to see with higher image resolution.

 

photo deleted because of limited data base at the forum

Can find no explanation for this. Any ideas?

 

Ciao Marco

Edited by Z320
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Hi Marco

Did your friend use the same refuelling stops as you, possibly contaminated fuel.

An interesting fault.

Paul

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Marco

I am no expert but those last pictures look like they have been very hot and lean.

https://i.stack.imgur.com/VTbgW.jpg

 

Perhaps check the mixture ?

 

As to the oiling if the car is not smokey out of the exhaust and doesnt use excessive oil I would think valve guides. I think you would notice it if it was the rings.

But I am sure others will be along to give you advice.

 

My old man always said its better to run it slightly too rich ( blacker plugs) than too lean. Lean can lead to damage.

 

H

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Thanks for your answers,

we started with 52 liters from different petrol stations, than had refills on the same stations.

But I am convinced 95 octan must be enough, he always takes 98 octan.

Driving behind him shows nothing special, we both checked oil and both engines need a minimum less than 0,5 liter / 1.000 km.

 

Marco

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Hi Marco,

#1 looks lean with an oil leak.

Could the dark stain be pointing at the valve hole and thus getting valve stem leaked oil directed on it. Leaky rings would be everywhere.

 

#2 look lean and very hot.

 

3 & 4 look a little lean

 

Regarding the white specks.

Does your friend have a brake servo AND use silicon DOT 5 brake fluid.

If there is a leak of fluid into the combustion chamber the silicon could turn into a hard sandy deposit at high temp. ( Blame Prof. Pete C for that)

 

Roger

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Hi Roger,

 

thank you but "sorry", he has no brake servo on his TR4....

 

If #3 und #4 are too hot I could lend hin a set of my Bosch plug,

I own them from W5BC (cold for driven hot engine), 6, 7, 8 (hot für cold engine).

 

I drive WR78G (short thread for 4 cylinder) and remenber one looks alway different,

can't explain that because it is the same carburetor, it's #3....

photo deleted because of limited data base at the forum

 

Any ideas for that? Actually I do not bother too much for that.

 

Ciao Marco

 

 

 

 

Edited by Z320
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Hi Marco,

#3 looks weak. You may have an air leak on the manifold close to the #3 inlet hole.

 

Have you got a tubular exhaust manifold ?-

if so it may have a thinner manifold plate than the original cast exhaust.

This will not allow the original pear shape manifold clamps to seat properly.

 

Just a guess

 

Roger

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Thank you Roger - but sorry: I use the original iron cast exhaust manifold,

But you gave me the idea to check if all nuts are tight - but sorry, they are all tight.

 

I could check if the inlet manifold is flat on the engine side, another project.

And I can switch the spark plugs #1 and #3 to see if #3 is different, that's fast to do.

 

Ciao Marco

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