Where next for timing on 1360?

[CarlM]

I still have some pinking in top and third when going up hill.

Firstly cooling side: I’ve had the radiator re-cored and run the engine with thermostat removed and observed good flow across radiator with cap removed. I run an 82 degree thermostat.

On engine/ ignition side: I’ve fitted a new distributor, double/triple checked the valve clearances and confirmed consistent and good compression on all four cylinders (160 psi).  I’ve confirmed that the distributor works in the sense that the timing advances with rpm.  Someone kindly posted a 1360 Lucas advance curve on the internet and i’ve set the timing both static (10 degree btdc) where pinking is worse, and dynamic to about 15 degrees advanced at 1500 rpm.

Plugs are correct NGK BP6ES and the plugs look good and even colour across all four cylinders.  I run the car on Momentum or Shell/Esso version of E5 fuel.

I’ve retarded using the vernier and still have some pinking when going up hill, in fact I’ve probably retarded it too much as it starting to struggle to get up the hills.

Not sure what to do next….any sage advice most welcome, the only other thing I noticed was a slight temperature difference when measured across cylinder head as shown below, with measurements in degrees celsius and spark plug numbers shown. Could be a red herring!
Thanks for listening

Carl

[johny]

What exactly is 'some pinking'? Triumph said if set correctly there should be pinking UP TO 2000rpm in top when accelerating hard on the flat. Obviously this will be worse up a hill, four up with luggage😁 However these days it is a bit unusual as people seem to be finding that with ethanol they can even advance beyond factory setting without pinking - me included as I used to use octane booster Millers VSPe but now find its not necessary...

[CarlM]

Simplest thing to say is that when running up hills, estimate 1 in 10 to 1 in 15 and even with a run at the hill say 40 mph trying to maintain speed by depressing accelerator causes pinking, and depending on hill dropping to third will also.

[johny]

If it falls below 2000rpm then pinking is permissible. However a weak mixture (especially manifold air leaks) will make things worse so try a little richer. I know its a new distributor but it might also be worth checking its advance with a strobe at different revs to check its curve matches the manual's...

[Pete Lewis]

just what /who's dizzy have you fitted ???is this electronic or mechanical points ????

and  are you sure this is Pinking, not piston slap or little end clatter or exhaust fouling with engine on torque ???

note that in most dizzy test data will show this is tested decelerating !!!!  thats quite important 

what coil is fitted should be a 3 ohm non ballasted coil  not a 1.5 ohm (across the blade terminals ) 

 

 

[CarlM]

Good questions. I obtained a Powerspark distributor, which I run with mechanical points. The coil is original, and can’t see a ballast.

pretty sure this is pinking as it disappears when easing off accelerator and sound like a tinkling noise.

I’ll ask about the curve for the actual distributor. 

[johny]

Also carbon build up in the combustion chambers can cause pinking although reckon that would have needed a previous extended period of poor running to form...

[Pete Lewis]

do you still have the old original dizzy to fit for  a test run comparison??

what problems did it seem to have ???

Pete

[CarlM]

Yes I still have the original distributor so can refit it.  Must admit that with the original one I thought that wear and tear and maybe weakened springs were giving me the problem so investment in new distributor.

I also invested in a £10 endoscope thing that works off phone, so I’ll pop that in the cylinders to take a look at top of pistons at least. May also invest in some STP fuel system cleaner on the basis it can’t do any harm.

[johny]

To test the weak mixture theory you can try a little choke when you next get pinking. Not too much but just enough to see if its worth pursuing the idea.....

[Pete Lewis]

so were you getting pinking sounds with the old dizzy fitted  ???

and you changed the unit to find its stiff   a problem ???

has the head been skimmed at some time in its life ??

excess fuel will give a wet pinking just as weak gives a dry one 

has someone fitted air piston spring  the 13/60 like the 1600 doesnt have one

this can richen the fuel ratio  when running   when at idle its fine 

Pete

 

[CarlM]

Pete/Johny

Many thanks for posts. A good few thoughts here, to try and answer some of questions.

I’ve only had car for 18 months so details sketchy on work that has been done, in fact sketchy is stretching it, the service book last entry was 1976 and no other details on purchase.  The cylinders pressures measured on warm engine are consistent and high. No idea really if head has been off and skimmed.

Yes the replacement distributor has the same issues as the original, in that pinking experienced with both, so that bit can be ruled out.

I’ll check the carb diaphragm and double check there is no spring present (although I haven’t looked myself discussion with garage at the time of fitting new metering needle confirmed this, but never assume!).

I haven’t checked the mixture, but was advised that it was set a bit rich, but probably a good opportunity to get the colour tune out!
 

I can check for air leaks on the inlet side, but on a quick glance there is nothing obvious there as all gaskets look good.

I did check and giving it a little choke did take the pinking away, this being a while ago and before making other changes.

I’ll also use endoscope to look at top of pistons etc.

regards

 

[johny]

What were the compression readings Carl - have you still got them?

[CarlM]

Yes Johny on a warmed up engine from gunsons tester they were consistent at 160 to 170 across all 4 cylinders.

 

[Pete Lewis]

that means your comp ratio is over 11 :1     far too high for a std  13/60 

you just need your ears to listen to mixture adjustment , turn the jet screw to give the best idle 

but without double checking the results  you are looking at a replacement cyl head 

Pete

Edited September 17 by Pete Lewis

[johny]

yes it depends on the instrument but that seems quite high on a warm engine and I wonder if as Pete suggests its had a heavy head skim. So, if all other measures arent successful dont discount raising your fuel octane level higher - either with a premium fuel or additive as I suggested... 

[CarlM]

Thanks for this, a few things to try and a likely solution. I was feeling happy with consistent compression numbers sitting in the ‘green’ range on the gunsons gauge, but now I’m not so sure……

[Pete Lewis]

the excess loads due to the high comp. can crack the piston crown at the ring groove 

that will give you similar to pinking noises till the crown breaks loose 

this problem is not a timing basic issue  , think  its elsewhere thats giving the pink 

can you borrow a gauge to reconfirm the high readings or dispel them ????

 

 

Pete

 

Edited September 18 by Pete Lewis

[CarlM]

Yes Pete, that is an easy first step and I’ll follow up at weekend. Thanks to you and Johny for pointers….

[Pete Lewis]

have you checked some muppet hasnt fitted air piston spring ??????

Pete

[CarlM]

Thanks Pete, I’ll be taking top off carb at weekend and checking condition of diaphragm and that locating lugs are in the right place, and no spring present!

[Pete Lewis]

we await the clues    Ha 

Pete

[CarlM]

I managed to accomplish most things on my to do list.

I’ve checked the carb and no spring fitted and the locating lugs are in the right place and the diaphragm is in good condition, not wrinkly and no holes etc.

I regapped the plugs and points and set timing to factory/workshop manual spec.

I obtained another compression tester and on warm engine got:

cylinder 1 - 130 psi, cylinder 2 - 130, cylinder 3 - 130 and cylinder 4 133 psi, so readings from original compression tester can be disregarded.

I also used endoscope and phone to have a look in the cylinders/top of pistons and presence of carbon detected! Images attached.

I added some STP full fuel system cleaner to a tank, on basis of it can’t make it worse, and it cleaned up the plugs nicely! And tickover a bit smoother. Appreciate this is a temporary expedient. 

forgot to mention that the car has only done 35000 miles, so wonder if head has been off at all.

last thing on the to do list was to adjust mixture, which I can do next week….