1972 Rover P6 3500 V8 Wont start?

Hi, It sounds a bit like the coil, Have you run a new 12v feed to the coil or are you still using the ballasted supply?

Colin

I know you say you have checked things but if it were me I'd check them in this order. I'm sorry to try to teach you to such eggs but this method hasn't really failed me. Otherwise you can end up spending cash you reall don't need to spend and potentially causing problems later ;I've had issues sourcing good quality coils for example, and in my Stag caused a problem because of that.

As we all know, you need three things to make an engine run; Compression, Spark, and Fuel. Having them right is key to making an engine run well. Now

1) Was it running lumpily previously? Does the engine sound like it has compression when being turned over? If not it could be flooded. In which case, start it as you would a flooded engine, preferably changing the spark plugs if you can or cleaning them. Otherwise, get a compression check done, unless of course something has broken (timing belt/chain for example, but the engine will sound 'strange' here if that has happened.

So, that's the compression. Next? The Spark.

1) Check to see if you have 6-9V (if it's a ballasted system; your workshop manual will give the voltage here) or 12V for non-ballast system. That will be with the ignition at No. II. When cranking the voltage will drop to whatever the battery drops to (10-12V). If it's stays at 6V or a ballast system or you have nothing at all that will be a wiring or ignition switch problem. Temporarily puttong 12V to the positive side of the coil will rule that out.
2)So, you have a working coil. Next, check the points? Does the gap look around right? If it's closing up or too open there is a good chance the car may not fire up. Adjust
3)See if you get a spark at the end of the King Lead, with a screwdriver/nail/plug in the end of the king lead? You don't It's like to either be the lead (a new lead can sort that) or the coil has packed up.
4) Grab a spark plug, pull a lead off another plug and see if it sparks as you turn it over. It doesn't? You have a spark problem. I'd also check one of the plugs in the engine to see if they haven't failed. If you have a spark at the lead the chances are either the firing order is completely wrong, the timing is miles off (unlikely to make it hard to start IME), or you have no fuel. Move on to fuel.
5) So you don't have a spark at the lead. I'd now check a few things. Check the dizzy cap. If the central carbon bush has gone from the middle of the cap the car will never fire up. You'll need a new dizzy cap. Also test the rotor arm. I've seen a few pattern ones fail and give a non-starting issue over the years, particularly ones from a company beginning with I. If it's not the cap check the leads.

So, fuel.
1) Can you see fuel going into the carb. If not you either have a blockage like a collapsed fuel line or a blocked filter. Otherwise it could be a knackered fuel pump. If it's mechanical it could be also down to the plunger arm or cam wearing (this is very rare however). On an electric pump it could be down to the wiring. Check these first before condemning the pump.
2) So, you have fuel coming to the carb. Can you smell it? If so, it could simply want setting up or you could have excessive fuel pressure going to it. Going to base settings here will work as per the workshop manual. On mechanical pumped cars it pays to crank the engine over a good few times on the key prior to trying to fire up. This IME makes a mechanically pumped car easier to start. Of course this is a little easier for those owners on electric pumps.
3) If you don't have fuel the carb again may want setting up, or the float may be jammed. Sometimes knocking the float will allow it to start again as the float unsticks itself.

If your case I'd be tempted to check that the dizzy is back to where it should be on static timing; is it clamped down well (i.e not moving).

I wouldn't rule out massive vacuum leak either. The car IME will generally run with a vacuum leak but badly.