Coked Up?

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J

jasonmarks

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Tring
Hi -
I've started to get what I think to be some pinking even when I retard the timing. I assume (wrongly??) that it might be that my engine (2 1/4l petrol 40 yrs old) is a bit coked up.
Other than taking off the head and doing a full de-coke, are there any other (simpler!) remedies? Are any of the liquid additives advertised actually recommended?
Any advice would help - thanks.
Jason
 
Start with the simple things and set the valve clearances/contact breaker points gap(or dwell angle if you can). Set the static ignition timing as per the book for your model.
How old is the fuel ? modern petrol can go off in weeks. I have made a new carburettor slide for my vintage motorcycle to get it to run rich enough on the present ethanol laced fuel. How long since the vehicle was driven a good distance on a main road?
Do the above and drive a good way before reaching for the spanners, modern fuels and oils do not tend to coke up engines.
 
Thanks for reply - the valves, dizzy and timing are all set well and the co readings are around 2% so i'm happy the set up is ok. It runs well (driven daily so new fuel about every 10 days!) and has for years, but just recently i'm noticing some pinking so I retarded the timing slightly but still exists. It gets driven about 30 miles a day, most of which on motorway. Would taking it for a longer run help you think? If so, how long we talking??
 
try a 20 or 30 mile non stop main road or motorway run then remove a spark plug to see what the colour looks like. That will tell you if mixture and running is OK (looking for a nice light chocolate colour)
Have you got any crankcase pressure problems ? You say that you have retarded the ignition so that should eliminate fuel issues. I have not had pinking on a low compression engine since the 1960s but a lot of short trips may have sooted things up a little.
 
Good point re distributor wear. I re-bushed the distributor on my V8 engined 110 defender, really made a difference to smooth running.
 
I would not strip for a de-coke, modern fuels just don't seem to cause coke in the same way so you'll probably find very little. I'm a fan of "Marvel Mystery Oil" - its an engine cleaner. I did a bit of research looking into the ingredients of engine and fuel system cleaners. There's one ingredient that dissolves burned on carbon, (I' forgotten what - not helpful) and this stuff has the most in of all the ones I looked at. Its pretty strong so you'll need to do an oil change after a while.
 
kurtjohnson10 said:
I looked at the title of this thread and got excited
Click to expand...
- sorry I was hoping the click bait would get more responses!
kermit_rr said:
Check for wear in the distributor and check is functioning properly?
Click to expand...
kermit_rr said:
Also are you on points or electronic ignition?
Click to expand...
- It's an electronic distributor - fitted about 4 years ago so don't think it'll be worn. Valve clearances are all as per the book and I think the mixture is set right as I put a gunson digital meter on it when doing it. would it pink if mixture is too lean? If so how would I adjust that as the carb screw is just for idle mixture isn't it??
I'll take it for a long run next time I'm off work though and then check the sparks as suggested and see what happens. Meantime
rob1miles said:
I'm a fan of "Marvel Mystery Oil"
Click to expand...
- will take a look and see if I can get hold of some as it can't hurt can it to run some through?
Cheers all so far..
 
A lean mix could result in the early onset of pinking. Get the spark plugs out an check colour.
A sure sign of carbon build up in an engine is the engine running on some after you have switched off the ignition.
Which carb do you have ?
 
tottot said:
A lean mix could result in the early onset of pinking. Get the spark plugs out an check colour.
A sure sign of carbon build up in an engine is the engine running on some after you have switched off the ignition.
Which carb do you have ?
Click to expand...
Engine stops cleanly. It's a Zenith carb - other than the idle screw is there anything else that might need adjusting the would help?
 
divie said:
try a 20 or 30 mile non stop main road or motorway run then remove a spark plug to see what the colour looks like. That will tell you if mixture and running is OK (looking for a nice light chocolate colour)
Click to expand...
took the landy out for a good run and pulled a plug as suggested - it looks to me like the right colour? (see pic)
IMG_6554.JPG
Not sure what else I can try??
 
So there's a slight 'ticking' noise at idle (which to be honest may have always been there but i'm now paranoid about the sound of the engine that I've been listening closely and can't remember if it always sounded like that! I think it probably did).
The noise I am assuming is pinking is a sort of, well, pinking noise when under load - say in 3rd pulling up a hill 25-30mph before changing up to 4th. When 'cruising' I can't hear the sound but there's so much noise through my, er, well ventilated cab, that it's hard to say if it's there or not. There's a definite pinky/ gravely rattle with high revs but only when driving. I can't get the same noise when I just throttle it when stationary.
Am i making any sense? I can try and run some more thorough tests tomorrow if that would help diagnose things?
cheers
 
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