Lotus Elan and Lotus Elan Plus 2 Forums

I have finally got the engine back in fine fettle following a battle to get the valve clearances sorted. After a run in for 1500 miles after the recent head rebuild, I torqued down the head (not much movement) and checked the valve clearances. Only two were in tolerance, with the exhausts between 7 & 8thou, and the inlets either too close or too wide by a couple of thou. With some trepidation as I haven't done this before, I removed the cams and miked up the shims - mostly around the 120-130 thou. I sourced replacements for the sizes I needed - with some compromises as certain sizes are not available from the usual sources (QED, Matty's, local workshop). Built up the head & checked clearances - bu**er - all slightly out again! I measure twice, shuffle them around again, rebuild - STILL OUT! I run the engine for a bit, let it cool overnight and try again. The previously measured clearances are the same, so there has been no settlement on running. Take it all apart, re-measure twice, write a little spreadsheet to eliminate my fuddled thinking. Rebuild with new shim sizes -hallelujah! They are all in tolerance. Close up, run the engine and take it for a road test. Bu**er, the engine is flat and gutless - valve timing must be out. Give up for the evening. Next day, pop the cover and check the timing, sure enough, looks like one tooth out on the inlet cam. Get the engine TDC with the cam chain tight on the exhaust side, slacken off the chain tensioner as much as possible, press down on the chain between the cams to max droop of the cam chain. Check exhaust cam is in still correct position using the mark on the cam sprocket. With a sigh of relief, the chain is just persuaded to pop over one tooth of the inlet sprocket to move into the correct position. Close up and road test - hooray! the engine is back to its old rev-happy self.

Tomorrow I will put a new gasket on & seal it all up properly. It sounds so easy in the manual, but then they are written assuming the engine is on the bench! Not stretching your back leaning over the engine bay, banging your head on the bonnet & trying to peer into the minute gap between the radiator and cam sprockets.. Oh well, I have learnt a few more things. Tippex marker pen is a life saver; use a powerful torch (LED) to see into the depths of the engine bay to check timing; and lastly - don't settle for 'near enough'.

Jeremy

Yeah, it's a crap/compromise design.

But surely easier if you whip the bonnet off?

And don't do what I did last time.
Rested the cams above the plugs whilst all the adjusting was going on.

Got everything back together, and was about to fire it up when a last check around
found a cam bearing nestled down around one of the plugs.....

Ralph.

robertverhey wrote:But surely easier if you whip the bonnet off?

Not so easy with a +2. Everything gets easier the more you take the ancillaries away. Timing gets easier if you whip off the carbs; turning the crank to check the clearances gets easier if you whip out the radiator and so on. Soon you get to the stage of thinking its easier to whip out the engine and put it on the workbench!.. Still, the trick with the tippex mark & the feeler gauge makes the problem of the bonnet less of an issue as I don't have to look at the front of the cam sprockets. Took a couple of goes to work that out.

Jeremy