Strange engine noise

Post by **53lake** » Mon Nov 15, 2021 10:48 pm

Perhaps someone can help me identify an unusual engine noise on my 1968 Traveller with original 1098 engine.

The engine was rebuilt at a local shop here in the USA (but not a British engine specialist). I supplied all the parts they needed from ESM, and the Haynes manual. New rings, bearings, seals, timing chain and gears, camshaft, valve guides, followers, oil pump. Added electronic ignition. They had no test bed at the shop, and I was working on the rest of the car, so it wasn't run until I put it in back home. I did check the valve stem clearances were set at 12 thou.

It seemed to run fairly smoothly on start-up, then this noise developed which I don't like the sound of.

Hopefully, I’ve attached a youtube link of the sound, with engine fully warmed up.

It sounds like a metallic clacking, similar to pre-ignition. It is hardly noticeable on cold start-up, but worsens on the run-up to operating temperature. It is most evident just as the revs increase from idle. Then at idle, it is intermittent. At higher revs it appears to fade (but might just be drowned out by the overall noise, can't really tell). It seems to come from the front of the engine, but not certain though.

I’ve removed the fan belt, and eliminated the water pump or dynamo as the source. I’ve put a long screwdriver to the ear on the timing chain cover, but that isn’t the source.

I’ve got the ignition timing set correctly at 3 deg BTDC at below 400 rpm idle with a strobe. Advancing or retarding the timing with the micrometer screw makes no difference to this noise. The mixture seems OK, the plug deposits are a nice gray, and there is no visible exhaust. I’m running on ethanol-free gas only. But the engine noise I’m trying to trace sounds very metallic, rather than a combustion problem.

I’m a bit nervous about tackling any longer trips in case I’m damaging something. I don’t want to go back to the shop that overhauled the engine without first having an idea what the problem might be.

Any thoughts most welcome – thanks.

https://youtu.be/wgZzXcfF01s