pinking

[poppet]

Hi
I'm modifying my 1963 morris traveller and am having a problem - pinking!
It has a marina 1.3 engine and back axle, 5 speed Sierra box, hs4 carb, 3 branch manifold, straight through exhaust, luminition ignition kit, lucas super coil and 8mm silicone leads.
Under normal driving conditions she drives well but under pressure e.g. hill climb, she will 'pink' until ease I f throttle. It then takes 2/3 minutes to return to normal.
Any ideas?
Thanks

[Packedup]

Fuel pump.

Failing that. maybe needle valve in the float chamber.

[bmcecosse]

Pinking is caused by poor quality fuel and/or ignition timing ! So first try top grade fuel (tends to give better mpg anyway) - and if it still pinks then retard the ignition timing till it doesn't. Pinking can ruin the pistons - don't allow it! It may be that the internals of the dizzy have failed - check the mechanical advance by twisting the rotor arm anti clock - it must spring back, and then check the vacuum advance by sucking the little pipe going to the dizzy. It should be dead-ended (ie possible to hold the vacuum) and the base plate on top of the dizzy should move as you suck and return when you gasp for breath. If it doesn't - then new vacuum advance unit needed.

[Packedup]

It's almost certainly fuel. More to the point, fuel flow.

The car drives fine until put under heavy load, when it needs the most fuel. The car then pinks, due to a lean mixture stemming from insufficient flow. When back to part throttle/ cruising the engine picks up again, as the demand for fuel is matched or outweighed by the supply.

I had exactly this on my Midget, the rear carb wasn't getting fuel under prolonged (long steep hill) load, and so was pinking and eventually loudly backfiring. A new pump fixed the problem straight away. With a single carb the effects wouldn't be as dramatic as two cylinders (one carb) wouldn't be being completely starved of fuel with the other two getting just enough - All 4 would be getting not enough to run properly, but not too little as to die completely.

[bmcecosse]

Sorry - I dis-agree - yours must have been a special case. Weak mixture could cause overheating - which could contribute to a tendency to pink - but 99/100 times it's ignition timing!

[Judge]

I had this problem during the LEO Run........it was timing.

[Orkney]

Niel had a trouble too at idle which was non existent remains of fuel pump points - well worth checking out for the sake of 2 mins.

[GAS]

I would agree with BMC.I have had to retard the ignition on my traveller so much I robbed the engine of a lot of its power,just to stop the pinking(bloody supercharger....)
I was also running rich.(sooty plugs) Super unleaded fuel helped slightly.
A new dizzy with a different advance curve has cured my problems and now the engine pulls like a train.

[poppet]

Thanks to all
I think I'll try the timing first - it has a new pump(fitted near the tank) and I already use top grade fuel.
I had to replace the distributor cap today - the brush and springs seemed to have 'burnt out' - I don't know wether this is significant or not?
I've also only recently fitted the hs4 carb - the fault occured while the original carb was fitted as well.
Any further advice is greatly received

[Packedup]

It then takes 2/3 minutes to return to normal.

This to me is the important bit. Why would incorrect timing fix itself after a while? More likely to be the fuel finally having the chance to catch up with demand after a period of starvation IMO.

Oh, on the issue of a new pump - Was it a pusher pump fitted if it's near the tank? If it was the (standard) Minor type then it'll struggle to get the fuel up front, though not to the extent displayed.

Another random thought that's just crossed my mind - A leaf in the petrol tank! I've heard of such things causing a partial blockage, and when the outlet is under the highest demand the "leaf" (or other such item) is sucked hard up to the pipe, when demand is less pressing the "leaf" can fall away enough to allow enough flow without problem!

[downsey]

I'd have to agree with bmc as well. It doesnt seem plausible that the pump would be able to starve the engine for more than a few seconds. Not to mention he states it is a brand new pump. The hill may be causing the engine to slightly overheat past normal driving conditions. Thus taking 2-3 minutes to cool down. Thats why its advisable to adjust the timing after accelerating up a hill or a mountain road. And retartding, as bmc said, until pinking stops.

[wanderinstar]

I was also running rich.(sooty plugs) Super unleaded fuel helped slightly.
A new dizzy with a different advance curve has cured my problems and now the engine pulls like a train.

I know the feeling. Isn't it brilliant when it all comes together. What dizzy did you use. Aldon by any chance?

[GAS]

I've just removed the Aldon dizzy i got from mini sport.I have now refitted the Dulseta(not sure if that is the correct selling)set up from an old Maestro.The Aldon one i got to try and solve another problem,that turned out to be something else.

[bmcecosse]

Ducellier ?
Did that Aldon have electronic ignition parts internally - or points??

[GAS]

I payed a fortune for it with points and got the electronic ignition later.