Griff 500 engine "pinging" at low revs

[tvroom]

My 1996 Griff 500 Serp "pings" at low revs (below 1500 rpm) when putting load on through each gear. The timing has been checked and is ok. I always use 99/99 RON fuel. Above 2000 rpm the noise totally disappears. Is there something more sinister in the engine of which I ought to be aware ?
Additionally, the engine is lumpy at low revs, and does not accelerate very smoothly. Any thoughts ?

[tvroom]

To all fellow/fellowesse Griff drivers, thanks for your combined wisdom, especially taking a harder look at the distributor and timing issues.

The prospect of a big-end shell being worn does not fill me with glee - the car has only 42,000 on the clock. But, nonetheless, very wise advice about dealing with it.

The settings and behaviour of the ECU are beyond my payroll grade; I had thought of upgrading it, anyway - Emerald has been recommended to me.

I shall investigate all these issues further and keep this post alive as I do so.

[tvroom]

Thanks BritishTvr45o : I appreciate your advice. I am onto the timing and distributor settings, which I shall exhaust before even thinking about the internals of the engine. Because the pinging noise disappears at over 2000 RPM, I have driven for over 1000 miles (on a tour) at normal road speeds. Whether deeper damage has already been done remains to be investigated ! Thanks for your comments.

[tvroom]

Thanks Blaze_away : I am reserving judgment on the engine internals until I am satisfied with a review of timing etc. Your info is good news, inasmuch as it does not need an engine removal and strip down, as I had imagined.

[tvroom]

Thank you, rev-erend.

Your Grace's advice is spot on - I have an appointment with my local TVR specialist tomorrow, to review options.

I trust that it is "electrical" and not "mechanical". All of the possible mechanical faults are inconvenient and expensive.

More to follow ........

[tvroom]

Problem(s) solved !

A deeper examination of timing settings revealed that it was way out; that was easily remedied.

The other aspect of lumpy performance was cured by replacing the distributor cap, rotor arm and plug leads. There were two leads where the casing was cracked and presumably the spark leaked out.

Needless to say, the Griff is running more smoothly than ever, with a complete absence of the pinging noise.

Thank you to all correspondents for comments and advice !