Herald Pinking (again, probably)

[Jon J 1250]

Hi,

I have just been giving my Herald 12/50 some more tests after a long layup and drove it up a nearby hill (for those who know it, Newlands Corner, between and Guildford and Shere, Surrey)

I just find the car struggling with the moderately steep hill on the A25, needed to drop to third, which is expected, but speed continued to drop with some pinking going on, also felt like I'd need to drop to 2nd gear for a bit, but the road started to level out in time.
From memory this car never liked hills, but I want to get the problem resolved.

I am using 98 octane fuel, the engine has had all service components replaced and is in good health, uses very little oil and good compression. It retains original spec manifolds and Solex Carb

Is this just a normal experience for a 60 year old, 1200 Herald, or can it be improved?

Cheers
Jon

Edited June 5, 2023 by Jon J 1250

[johny]

First need to check timing setting and also colour of spark plugs...

[Pete Lewis]

the base 12/50 is well able to  keep up with reasonable traffic  so it cont set the perfomance on fire they are well able to some quite lively easy running 

so something is   not right 

agree with Johny recheck the timing  there is little of the downdraft carb apart from fuel supply 

do check the short pipefrom the top of the tank this is hidden in the boot and often gives  air leaks 

Pete

[johny]

Apparently the official test for acceptable pinking is: under full acceleration on the flat in 4th the noise should end on reaching 2000rpm. If this cant be achieved and all settings are correct then the fuel octane has to be increased or the timing retarded....

[Jon J 1250]

9 minutes ago, johny said:

Apparently the official test for acceptable pinking is: under full acceleration on the flat in 4th the noise should end on reaching 2000rpm. If this cant be achieved and all settings are correct then the fuel octane has to be increased or the timing retarded....

Ha,

I have heard this before, should be interesting, will have to work out/look up what road speed 2000rpm equates to with the standard 4.11 diff.

I can imagine there'll be plenty on tinkly sounds from the top end of my engine.

 

Something else i've noted is the car really struggles with the short steep ramps up to my garage, the other day it flooded and died while i was driving it in, however the car performs absolutely fine on the flat.

Edited June 5, 2023 by Jon J 1250

[johny]

Hmmm might be worth checking the carb float level setting and condition 🤔

[Josef]

2 hours ago, Jon J 1250 said:

Newlands Corner

I used to live in Merrow and definitely know Newlands Corner, and it happens to be the place Agatha Christie’s car was found when she disappeared for a week or two!

[PeteH]

Cafe at the top of the Hill?. On the old A25?. Vitesse used to whiz up it, back in the 80`s. on the way the Redhill Before they opended that M25 Section.

Pete

[Jon J 1250]

1 hour ago, PeteH said:

Cafe at the top of the Hill?. On the old A25?. Vitesse used to whiz up it, back in the 80`s. on the way the Redhill Before they opended that M25 Section.

Pete

Yes, that’s the place.

[Jon J 1250]

Had an hour to spare so sorted investigating, plugs look about right colour, I’ll re gap them.

Points gap fine, dizzy looks in good nick (57k miles) well oiled and no lateral movement on shaft.

Interestingly, I think the rotor arm is very old, may even be the original one judging by the divot worn in the middle.

The three nos Lucas replacements I have are a different shape, no counterweight!

Will have more time tomorrow so will start looking at timing.

[Wagger]

Do as others suggest first, then, if no success, check the valve timing. Camshaft could be retarded. I had a Dolly 1500 that was gutless uphills due to cam being two teeth retarded.

[AndyTV8]

Those plugs look very lean/hot to me - I’d be checking the timing, could well be overly retarded.

………. Andy

[Wagger]

As a sequel to my last post, advancing the ignition when the cam was two teeth retarded resulted in more power but severe pinking. That was on 4 star leaded too.

Sorting the cam timing cured all of it.

It was very easy to get the cam timing wrong for me as I was used to BMC 'A' series where keyways point at one another for correct cam timing. This is not so with Triumph engines. See workshop manual.

 

 

 

 

 

 

[Pete Lewis]

if you read the manual its quite easy to check valve timing by using large tappet gaps and TDC  just follow the words in the manual 

the cam sprocket has 4 holes  and if you turn it over more 4  each set gives incremental adjustment of 1/4 tooth 

many are hopelessly mal adjusted and power loss is inevitable,  

using the rockers is simple and doesnt need any strip down  just a set of feelers and your eyes 

i can spell out how too  but best you read the manual or get one for fathers days wish list 

pete

Edited June 6, 2023 by Pete Lewis

[Jon J 1250]

4 hours ago, AndyTV8 said:

Those plugs look very lean/hot to me - I’d be checking the timing, could well be overly retarded.

………. Andy

Thanks, I think it is the LED light making it look blueish, in natural light the colour is a sandy brown, very similar to the normal picture in the good old Haynes guide.

I'll give the Solex Idle/mixture screws a tweak though as per the workshop manual.

[Jon J 1250]

Thanks for tip on cam timing too, Wagger and Pete.

I am pretty sure the timing gear has never been apart on this engine, which has 57k miles on it as the first owner prior to my purchasing it in 1995 kept meticulous records, so assume it was set up correctly at the Canley factory.

[Pete Lewis]

what does happen is the links and pins in old chains do wear and this makes the chain effectively a bit longer than a new one

yes the tensioner takes up this excess length by keeping the tension by its spring 

however the worn length is on the drive side of the sprockets not the tensioner side so the cam timing does over the years become late

easy to compensate the timing by adjusting the dizzy but you cant compensate for the worn chain 

fitting and retiming a new chain can make an appreciable difference in the wear an tear brigade 

always worth considering   one day 

Pete

[Jon J 1250]

I've turned my distributor a fraction of a turn anti-clockwise to hopefully retard the ignition slightly and stop it pinking on hills (it already was fully retarded on the vernier).

Now it idles smoothly as it always did, but it is gets very lumpy and misfires when you rev it.

Is this a symptom of retarding it too much?

[Jon J 1250]

Ok, I got it right, actually had to rotate the distributor anti-clockwise and fully retarded on the vernier almost as far as it would go (the limit being the length of the original vacuum tube) to get it to rev smoothly, and the Herald engine is an exceptionally smooth 4cylinder in my experience.
Then have progressively advanced on the vernier it a bit at a time until it just starts to pink on hills, then will backed it off a few clicks.

Power seems about the same (i.e. not very powerful, and I accept that's what 1200 Heralds are) but it will happily climb a hill now, so that's a result in my book.

Thanks all

[johny]

It would be interesting to see where the dynamic timing is set now as even though not pinking you could still be more advanced than design...

[Jbc562l]

I understand that a combination of engine wear, modern fuels and perhaps additives , mean that traditional timing marks from a 60 year old workshop manual are “a place to start at best” .

If I’m right there are no dynamic timing settings quoted for the 1200, so start by timing using the recommended static. Use one of the modern timing guns that will read off the degrees BTDC for you . Using that figure as a starting point advance the ignition until you get a fast smooth idle, you may need to adjust tickover. 
 

Test drive and check for pinking, Agatha Christie’s hill is ideal ! Retard until pinking stops .. write down your bespoke BTDC figure for future use. And try to keep the fuel octane consistent as well. 
 

This worked for me.hope it helps.. 

 

Ps: if I can find where I wrote it down I’d quote my BTDC figure ! I think it was high teens.

Edited June 30, 2023 by Jbc562l

[dannyb]

After a rolling road tune my spit is set too 17 deg btdc. Using high octane fuel.

Danny 

[johny]

1 hour ago, Jbc562l said:

Test drive and check for pinking, Agatha Christie’s hill is ideal ! Retard until pinking stops .. write down your bespoke BTDC figure for future use. And try to keep the fuel octane consistent as well. 

Some pinking is to be expected and is perfectly acceptable. As Ive said before it can pink up to 2000rpm in 4th accelerating hard on a flat road but should have finished by that point.

However theres no point advancing timing beyond the manufacturers figure even if your within the above limit, it wont give you anymore power😞

Edited June 30, 2023 by johny