Technical I visited the land of Fiat - Timing problem

[rawill]

We spent 3 weeks in Italy, loved it, difficult trying to figure out the road rules though. An Italian lady told us "road rules are only a suggestion"

Anyway, my trusty 84 Uno 1300 pings far too much, I set dwell to 58, timing to TDC, it has 50% 91 octane and 50% 95 octane in it. I put in Wynns Race Formula octane boost but it made no difference. I used the ball bearing pointer on the flywheel to time it. What have I done wrong?

 

[SteveNZ]

How are the plugs?
How old is the gas?
Is the dwell correct? I have no idea.
Does it have vac advance, working?
does it advance properly with RPM?

Ignition timing can be done off the front cover, there should be TDC 5 and 10 degrees.

 

[rawill]

Gas is new (above), plugs good, dwell 58 (above) timing set at TDC, mechanical and vaccum adv seem fine but am going to check again, no adjuster on my timing light to wind the light back and get a good reading, have to go to local garage.

 

[Chas Uno]

Gas is new (above), plugs good, dwell 58 (above) timing set at TDC, mechanical and vaccum adv seem fine but am going to check again, no adjuster on my timing light to wind the light back and get a good reading, have to go to local garage.

Timing should be 10 degrees at idle, with the vacuum advance disconnected and the vacuum pipe plugged. You loosen the base plate bolt then rotate the distributor to adjust the timing. If you've set it at TDC that might be what the problem is. Use a timing light to set it dynamically at the correct setting.

 

[rawill]

Setting it to TDC means it is retarded, which should stop pinking (in my thinking). Yes 10 BTDC, (before top dead centre) is the correct timing as you explain. I am going to run the petrol down to empty and put in 95 and see how it goes. I am confused as to why setting to TDC doesn't stop the pinking.

 

[SteveNZ]

Preignition due ot carbon, hotspots etc

 

[rawill]

Mmm, maybe. It was also suggested that the timing mark could be in the wrong place, it has been known to happen but I reckon it is a longshot.

 

[alexGS]

Mmm, maybe. It was also suggested that the timing mark could be in the wrong place, it has been known to happen but I reckon it is a longshot.

You're right - TDC should have stopped the tinkling (and drastically reduced idle speed and top-end power...)

I agree with Steve - carbon buildup inside cylinder head as a result of rich running over a prolonged period (not unknown with the two-barrel carb). I always use the timing marks on the flywheel, through the window in the clutch bellhousing - they are either exactly right or out by 180 degrees, since it is possible to fit the flywheel upside-down...

-Alex

 

[jjhepburn]

Is it easy to start when the engine it hot? If it has difficulty turning over when hot then I would definately think its a carbon buildup. Take the car for a big long trip.

 

[rawill]

Sorry a while since I have been back. Yes it is easy to start, either hot or cold. I gave it a bit of a hiding the other day, like a real caning through the gears!! blew some gunk out the exhaust. Still pinking though, will run it right down in fuel and put 95 in and see what happens. I will see if I can set it back to to 10 BTDC without it pinking.

Thanks for your interest.

 

[rawill]

I am running out of ideas now re the pinking!!
I have just run the car down to less than a 25% full of fuel and filled it up with 95 octane. It is still pinking with it set on TDC. I am wondering if the cambelt could be a tooth out. If it was could this be the reason I can't get it right. I have heard of this kind of thing before. And to JJhepburn, it usually is fine turning over when hot, but sometimes, very seldom, it sounds like it is too far advanced when it is hot, but it also inconsistent.