The effects of modern fuel on old engines. Many questions...

Post by **bmcecosse** » Thu Feb 08, 2007 8:12 pm

Aye - it was over-lubed - but that shouldn't have caused the valve to fail like that.

Post by **Dominic** » Thu Feb 08, 2007 8:37 pm

A local supplier (not the one that sold me the head) advised that it was probably carbon build up that stopped it (valve) seating properly, leading to overheating until failure. There were signs of overheating on the inlet valve stem too, beginnings of seizing up.

Post by **minor_hickup** » Thu Feb 08, 2007 9:52 pm

rayofleamington wrote:
Funnily enough I seem to get 2k from brake light switches before I take it back to the supplier and they declare
You could try getting an original one from a scrap Minor. That could possibly outlast the next 10 brake light switches you get from this supplier.

I did post in the wanted section, but alas to no avail.

On a high mileage A-series, things like a failed valve are a pain in the rear but just part of the 'character'. Valves used to fail in the 70's when we had good old leaded fuel - long hard runs are a major factor to cause this.
Despite an uprated unleaded head the risk of failure is never reduced to zero (although it is reduced significantly) and also the materials used in new spare parts are not always as good as they could be.

I think its pretty good going for what the car does, given the age and the fact the angine has never had any major work except for the unleaded head.

Post by **rayofleamington** » Thu Feb 08, 2007 11:34 pm

I did post in the wanted section, but alas to no avail.

Ah -ok . Good plan.

There's a couple of people breaking their Minors - it might be worht to chase them up if/when you need another.

Post by **minor_hickup** » Sat Feb 10, 2007 1:06 pm

I think thats what I'll do, cheers Ray. I think I've got another 1,000 left on this one yet

Post by **Kevin** » Sun Feb 11, 2007 9:31 am

Doesn`t modern fuel contain more Benzine that the old style fuel which is why many classic cars suffer from old style rubber fuel lines suffering from leaks especially older fuel injection systems, and petrol used to be a recomended way of cleaning old parts but the modern fuel is not due to its chemical makeup.

The previous owner of my car ran it on pure unleaded for (I assume) about 5 years and I continued to do this, using the car everyday. I do tend to hammer it a bit, using full throttle to accelerate a lot of the time.

When the tests were done on the fuel additives it was found that valve resession on the `A` series only really started at speeds above 55mph, so if the previous owner didnt drive above this speed much so he got away with it, until it passed into a more enthuiastic driving style owner