2.25 pinging

[wozapinin]

I’ve recently purchased a 1971 shorty I’m trying to get running sweet but I can’t stop it from valve bouncing under load (even high revs stationary it pings) I can adjust to run sweet at idle/low revs but retarding it so it runs like a dog it still pings.
The previous owner said the head was rebuilt to accept unleaded so shouldn’t be issue.
I have tried new coil, plugs, converted original Lucas distributor to electronic, replaced that distributor with brand new Lucas (back to points). Fuel mixture screw on carbs needs to be wound in almost all the way before needing to back it off half a turn.
Any ideas as to were to next?

I lost my dad late last year and he was the man when it came to land rovers and anything mechanical. Had a way of seeing things from a different perspective. Didn’t always make sense to start with but he was usually on the money.

[JDNSW]

As a general rule the only time that this engine will ping is when the ignition is too far advanced.

I can see a few possibilities:-

1. You are misidentifying 'pinging', and it is something else, possibly an issue with the timing chain.

2. It is fitted with plugs that are far too hot. I have never had that with this engine, but did years ago with a two litre.

3. You say the head was rebuilt - it is possible the head was skimmed to increase the compression ratio to where it needs premium fuel - try that.

4. Less likely - vacuum advance is not working.

5. Need to take off head to check - something, possibly a result of the work on the head, or damage during fitting, has left a bit of metal in at least one combustion chamber that gets hot enough under load that it will ignite the fuel. Could be either a still attached cutting from the machining to allow fitting of hardened valve seats or a part of the head gasket.

Hope these ideas help

[Aaron IIA]

Have you checked with a timing light to see that the ignition advances with increasing speed, but retards with a sharp opening of the throttle?
Valve bounce should only be a problem above the maximum running speed. It shouldn't happen below 4000rpm.

Aaron

[Blknight.aus]

you could also have carbon fouling thats getting a hot spot.

[Aaron IIA]

When my SIIa ran on petrol, some days I could park it, switch the ignition off, get out and lock the door, but it wasn't until I had walked a couple of metres away that the engine actually stopped. I used to run warmish plugs to stop them from getting fouled with oil.

Aaron

[wozapinin]

As a general rule the only time that this engine will ping is when the ignition is too far advanced.

I can see a few possibilities:-

1. You are misidentifying 'pinging', and it is something else, possibly an issue with the timing chain.

2. It is fitted with plugs that are far too hot. I have never had that with this engine, but did years ago with a two litre.

3. You say the head was rebuilt - it is possible the head was skimmed to increase the compression ratio to where it needs premium fuel - try that.

4. Less likely - vacuum advance is not working.

5. Need to take off head to check - something, possibly a result of the work on the head, or damage during fitting, has left a bit of metal in at least one combustion chamber that gets hot enough under load that it will ignite the fuel. Could be either a still attached cutting from the machining to allow fitting of hardened valve seats or a part of the head gasket.

Hope these ideas help

Hmmm, timing chain. It’s not a quiet knock.

[4bee]

Were new springs fitted?

If the old ones are weak would it not be easier for the valves to bounce ?????????????

[Aaron IIA]

It is possible, although I do take mine to 4000rpm and I have never experienced valve bounce. I have not replaced the valve springs.

Aaron

[JDNSW]

This engine is quite happy to rev at over 4,000rpm, and I have never encountered valve bounce on one.

[ian4002000]

Pinging and valve bouncing are two completely different things.
Pinging sill usually only occur under load and should stop when you lift your foot off the gas.
First thing with pinging is to put fresh and high octane fuel in the tank.
Run the engine and use most of the fuel and then refill the tank with good fuel, BP is probably the best quality, avoid cheapo fuels as they may be a low octane.
If the engine is still pinging you need to check the timing and that the timing advances when the revs increase.
You may need to disconnect the vac advance tube to ensure it hasnt advanced the timing, if it is still pinging after checking the timing then start retarding the distributor and see if this will stop the pinging.
If you cant get it to stop, then you will probably need to remove the head and see if there are any problems with the head gasket or head, valves etc. There may be a lump of carbon on top of a piston.
If the old days we used to do a decoke of pistons etc to remove the unburnt deposits on the head etc.
You should be able to see if anything is wrong or post pictures of what you find in the engine.
I have a similar problem with a friends series 3 and we are removing the head later this week, i am expecting to find the head gasket has a crack in it. This Landy blows white smoke occasionally and runs on sometimes.

Valve bouncing occurs when the engine revolutions are faster than the valve springs can handle and the engine starts running very roughly. Some times a valve can hit a piston and get bent. Valve bouncing doesn't usually happen with a 2.25 but anything can happen.

I hope this helps

Ian
Bittern

[wozapinin]

I’m starting to think fuel? Adjusted the valves today, they where real loose. She runs heaps quieter but not the fix. I can adjust so timing light is showing tdc and it runs sweet on idle but the valves go nuts when giving it a rev...stationary. I can retard it so it runs like a dog and it will stop the noise at stationary...but drive it under load and the valves rattle. Might drop the fuel and put some fresh stuff in.

[Aaron IIA]

Just so that we are all clear, do you have a problem with noisy valves, or pre-ignition? These are two distinct problems with different noises.

Aaron