13-05-2025, 05:48 PM
John, I wouldn't lose sleep over the odd bubble at the plugs, unless they are totally failing to hold pressure.
If you suspect a valve isn't closing / sealing properly that certainly merits further investigation.
You'd do well to acquire the art of checking the tappets - with feeler gauges - 'blind' - it's a bit of a fiddle but beats removing the engine from the car every time you want to check them. Feel for the head of the tappet screw and slip a suitable sized gauge across it. If it won't go in try a thinner gauge. Making sure you've got the correct tappet and the correct position on the stroke, of course!
If the tappet clearance is good, it's head off, visually check the valve seat and lightly grind the valve in as required. Then re-set the tappets.
It involves a bit of stooping over the car but it's all do-able with the engine in situ.
If you suspect a valve isn't closing / sealing properly that certainly merits further investigation.
You'd do well to acquire the art of checking the tappets - with feeler gauges - 'blind' - it's a bit of a fiddle but beats removing the engine from the car every time you want to check them. Feel for the head of the tappet screw and slip a suitable sized gauge across it. If it won't go in try a thinner gauge. Making sure you've got the correct tappet and the correct position on the stroke, of course!
If the tappet clearance is good, it's head off, visually check the valve seat and lightly grind the valve in as required. Then re-set the tappets.
It involves a bit of stooping over the car but it's all do-able with the engine in situ.