Talk Morgan Forums Community Vehicle Talk (non-Morgan) TDC and tappets

T`was not until I was involved with Lotus/Jaguar that I discovered that lovely quiet valve clearances were indeed a sign of danger ahead and the possibilities of burned valves and seats, for it seems for whatever reason Jags valve clearances may be prone to closing... Don`t ask me how that might come to pass, I just remember finding tight clearances were the cause of a hard to start Jag I once owned and also tight clearances on an Elan.. Go figure..?

Where is Spanner Juggler AKA Colin when you need him, Colin was ever the one who kept us informed as to the shortcuts and tricks of the garage trade...

He is here George, just been busy with daughter buying a new house and moving and grandad duties.

OK, quick scan through some of the posts on this subject so forgive me if I miss something or get the wrong end of the stick.

In no particular order, valve clearances closing up, mainly down to valve seat erosion and valves pocketing in the head, because of the ratio of cam lift to valve movement even a small amount of valve pocketing can close a valve clearance considerably. As an aside I never bothered with valve noise on a competition engine and used the valve clearance to regulate the valve timing on individual cylinders. So long as the gap never went below the minimum stated a few thou extra to ‘phase’ the valve timing with a clock gauge and DTI was the way I set them up. It’s amazing how much inaccuracy there is in even brand name camshaft lobe phasing!

Ascertaining TDC for checking valves, again not that critical as the clearance is set on the back of the cam so when the valves are ‘on the rock’, you can achieve exactly the same effect by (on a petrol engine) turning the engine with distributor cap off and setting the clearance for both valves on the cylinder that’s firing (it will be very close to TDC and both valves on the heel of the cam.

On a ‘Satans Fluid’ engine it’s more difficult but if your struggling to turn it over don’t forget unless it’s an automatic you can pop it in top gear and rock it to observe the valves and get them on the rock for adjustment. Just use care that you don’t bump start it, if it’s ancient pull the stop cable out, if it’s modern crack open the injection pipes.

Hope that helps, back to entertaining a 6 and 13 year old…… they may end up on eBay 🤣

BR
Colin

PS

Forgot to say that many old Satans Fluid engines use a ‘Ricardo Comet Anti chamber’ and the diesel is injected into this and starts to burn there before the flame spreads to the main combustion chamber. Because of this popping a piece of wire into the injector or glow plug hole to feel the piston doesn’t work.

BR
Colin

Hi Colin, always good to read that which you type, I hoped that topic might grab your interest.. I had forgotten all about valve seat recession... Duh ! Perhaps made worse when unleaded fuel arrived on the scene.

Sorry to drag you away from the entertaining the kids....

Not heard from you for a while Colin, how are you doing sir ?

Still here just not online so often these days. It’s hard after selling the Morgan after nearly 22 years.

BR
Colin

Good to hear from you Colin!