sudden increase in engine pinging and overheating

[alfheim]

Hi guys. 
I've had my P5B saloon for about two seasons now, and have driven it a bit and I'm really liking it. I guess I've done something like 2000 miles over the last year and have had few problems in that time. 
When I bought it, the guy I bought it from installed an electronic ignition before I picked it up. (I do not know the type, but I guess I should be able to find out). Anyways, from the get go there was a bit of engine pinging/knocking when pushing the accelerator hard. I've been running on 98 Octane fuel, with a lead replacement which to a certain extent should also boost the octane, by how much I don't know. 
Last autumn I had a mechanic look over it, and asked him to adjust the ignition also, as there was some pinging, which I think he did. I believe the pinging was reduced, but not 100% gone. 
However, on Sunday, there was suddenly a lot more pinging/knock from the engine almost regardless of engine load, (any touch of the accelerator lead to pinging) and the engine came very close to overheating (moving into the red, and starting to let out steam) after just a 10 mile journey. 

I'm assuming the overheating was caused by the knocking, not the other way around. 

Anyways, I was just wondering if any of you had any ideas as to what could cause this sudden increase. I checked the distributor, and it seems to be well fastened, so I don't think it has moved. Just looking for ideas as to where to start my investigation. 

Suggestions I have received so far is to do a compression test as a blown head gasket could lead to water entering the cylinder and increasing compression. I would have thought that would lead to more significant coolant loss though. But will check that. anything else I should be looking at? Will check the timing of course but, just don't think it has moved. 


Regards 

[enigmas]

Try and discount the cause of your car's issues first by reasoned deduction alfheim.
These seem to be twofold.

1. Engine Pinging under most throttle settings (light & heavy)
2. Overheating.

First off...the electronic ignition won't cause the engine to ping, if anything it will provide more accurate and consistent firing cyl to cyl.

OVERHEATING.
Possible Causes:
* Cooling system/radiator clogged/damaged.
* Thermostat stuck closed or incorrectly rated thermostat. (180°F or 82°C is a viable operating temp)
* Silted up engine block.
* Retarded ignition system.
* Choked exhaust system.

PINGING.
* Over advanced static timing.
* Centrifugal advance occurring to early. Missing internal spring on weights/incorrectly setup.
* Vacuum line to advance capsule on distributor incorrectedly plumbed.
The vacuum line for this unit is plumbed in front of the throttle blade (air filter side...known as 'ported' vacuum) It should not be plumbed from behind the throttle blade (manifold side...provides full vacuum as soon as the engine starts) otherwise it will fully advance the capsule on closed or light throttle.

Note: The vacuum capsule should only provide additional advance during steady state cruise conditions...this improves both the fuel burn and fuel economy.

[lagain]

When my engine was badly rebuilt by a supposed specialist, after a while a head gasket went. I accelerated hard to pull out in front of a line of traffic and they disappeared in a cloud of steam, so usually visible from the exhaust. Another sign is when removing the radiator cap when the car is totally cold and it hisses.
If your car still has high compression pistons it will pink more and some brands of petrol are better than others.

[Welsh Warlock]

If it has an ignition module on the side of the distributor try changing that.

My car used to pink with the old unit fitted but I changed it (after trying to set the timing many times to try and eliminate it without success) and its fine now.