Tappet like noise

My x1/9 1500 has developed a tappet like noise
Any advise appreciated. How difficult is it to check tappet clearance
replace shims or could it be broken spring,
Thanks

If you remove the rocker cover you can access the tappets. The problem is that engine is inclined towards the bulkhead making it a bit more difficult to see what you are doing. The Haynes book details the procedure for checking the clearances.

Incidentally, I once had a tappet like noise on my earlier 1500. It turned out to be a leaking exhaust manifold gasket.......

As Andy says tappet like noises can come from many unexpected sources. If you buy a engine stethoscope that will help you track down the location. However, the valve clearances once set should not need a adjusting for at least several thousand miles and so any rapid increase in noise is likely to be from another source. If it does turn out to be the tappets then you need a special tool (not that easy to find) to hold down the valve bucket/shim arrangement while you retrieve the shim to change for another of a different thickness if, after measuring, the clearances are out. Its a tricky job with the engine out and more so with the engine in. You'll also need to budget for ?? number of new shims after you've worked out what new thickness's you need.

Thanks for both of your advise.
I used a stethoscope yesterday I am now convinced it is not valve clearance.
The Stethoscope was loudest when held on engine mounting bracket by the timing belt. I checked tension bearing and all pulleys on the trimming belt, bearing all smooth. I also checked alternator which was also smooth.
Did not have time to investigate further.
Any advice would be very much appreciated.

Update
Used stethoscope all over top of engine and all areas I could reach.
As soon as engine reaches running temperature the tappet type noise stops, so will have to go under car with engine running.
Why do we love our x1/9 when hey always have the last laugh.:evil: :evil:

Might be worth taking a closer look at the exhaust manifold gasket as Andy has already mentioned. If the gasket has split, once it gets hot and the gasket expands, it will effectively self seal. It is a common issue with the Fiat Coupe, albeit caused by a cracked manifold rather than its gasket.

Would I not hear noise with Stethoscope held on exhaust manifold ? This I did and no tappet like noise.