Displaying items by tag: XK

A club member was having trouble with his XK series engine as it refused to fire up after having the carbies overhauled, new points, plug leads etc. put into the system along with a distributor overhaul. The engine refused to run and wouldn't even do the courtesy of giving the occasional backfire or cough. Club member was getting a bit frustrated with the whole thing

Enter yours truly and a few basic points were looked at. Spark plug removed from the front [number 6 cylinder in Jaguars] and a crank over to the compression stroke showed that the distributor rotor arm was pointing at the lead going to number 1 cylinder i.e. all of the leads out of the distributor cap were 180 degrees out. The spark plug leads were reattached in the correct order but still no signs of life when cranked. Careful checking of the float levels in the SU HD8 carbies showed no major discrepancies. There were lashings of sparks as yours truly got inadvertently zapped while holding onto a plug lead and noting that the spark would jump a ½ inch or 12 mm gap. A rough check on the timing showed it to be within the general running range of a few degrees before top dead centre. The fuel strainer bowl was checked for water and it came up clean so basically we had fuel, ignition and compression but still not a running engine.

When all else fails suspect any thing so I pulled the plugs out which were decidedly wet. I can only presume this occurred as petrol evaporated causing water condensation on the plug insulation. After washing them in petrol and drying with an air gun they were reinstalled. A dash of ether start assistance had the engine firing but refusing to idle. Keeping a fairly wide open throttle setting helped keep it running and eventually it stabilised at 1500 RPM, - still not right.

By now it was obvious there had to be a major air leakage in the inlet system as no amount of fiddling with the main jet enrichment system was having much effect on the idle. By sheer luck while suspiciously looking at the engine running from all angles I spotted a joining hose on the starting carbie pipe inlet system that had become disconnected and had left a significant opening for air to bypass the carbies. Apparently the hose had been installed but the hose clip wasn't tight and a backfire in the inlet system had most likely caused it to come off.

Reconnection of this pipe brought some order into the system and after this final mechanical skirmish we had the car idling. There was still a little leak somewhere in the inlet system as the engine was happily idling with both carbie idle air bleeds completely shut off! The best way to chase these leaks is by using a piece of thin hose held to the ear while the other end is moved around the inlet manifold and carbies. However time was running out and I had to leave this up to the owner to pursue.