Diagnosing a lovely knocking noise

[donnybach]

Nice one.

[motorang]

So you did not find any loose parts or wear, and apart from gaskets the only thing you changed was the camshaft including decompression mechanism?
Piston etc still the same?

Andy

[dan3]

So you did not find any loose parts or wear, and apart from gaskets the only thing you changed was the camshaft including decompression mechanism?
Piston etc still the same?

Andy

I didn't change the camshaft in the end as they all disappeared from the Internet once I started looking for one. I only changed the gaskets and set the valve clearances.
Maybe the timing was out ever so slightly? Is that possible?

[motorang]

Did not sound like it, really. No loose engine frame bolt?

Andy

[scottieh]

So you did not find any loose parts or wear, and apart from gaskets the only thing you changed was the camshaft including decompression mechanism?
Piston etc still the same?

Andy

I didn't change the camshaft in the end as they all disappeared from the Internet once I started looking for one. I only changed the gaskets and set the valve clearances.
Maybe the timing was out ever so slightly? Is that possible?

On a number of different xt’s I have accidentally made the valve clearances be way way off when resetting them. I would rotate the engine to tdc, set the clearance, and then rotate the engine a few times only to find that my clearances were off by a mile. Somehow the original tdc wasn’t properly setting the rockers or the valves or something got off and i had to do the valves a second time to make sure the clearances were right. If not double checked before closing up the engine and running it, that gap between the rockers and valves would make the kind of knock in your video. Obviously too late to know now if that was the case since everything got taken apart and put back together but that has been my experience in the past.

Glad it’s all running smoothly for you!

[donnybach]

It definitely sounds like the valve to me. I’d be interested to know if that newer decompression system you had can stick open too. Just glad your sorted. Lovely motors when they’re on.
Just need a good synthetic fuel supply in the future to keep em going.

Surely the energy in space dust sherbet in the ‘70s could be harnessed?

[dan3]

Did not sound like it, really. No loose engine frame bolt?

Andy

Nope

[dan3]

So you did not find any loose parts or wear, and apart from gaskets the only thing you changed was the camshaft including decompression mechanism?
Piston etc still the same?

Andy

I didn't change the camshaft in the end as they all disappeared from the Internet once I started looking for one. I only changed the gaskets and set the valve clearances.
Maybe the timing was out ever so slightly? Is that possible?

On a number of different xt’s I have accidentally made the valve clearances be way way off when resetting them. I would rotate the engine to tdc, set the clearance, and then rotate the engine a few times only to find that my clearances were off by a mile. Somehow the original tdc wasn’t properly setting the rockers or the valves or something got off and i had to do the valves a second time to make sure the clearances were right. If not double checked before closing up the engine and running it, that gap between the rockers and valves would make the kind of knock in your video. Obviously too late to know now if that was the case since everything got taken apart and put back together but that has been my experience in the past.

Glad it’s all running smoothly for you!

Cheers scottieh, I'll bear that in mind if it happens again.

[dan3]

It definitely sounds like the valve to me. I’d be interested to know if that newer decompression system you had can stick open too. Just glad your sorted. Lovely motors when they’re on.
Just need a good synthetic fuel supply in the future to keep em going.

Surely the energy in space dust sherbet in the ‘70s could be harnessed?

I'll be drilling for my own oil if need be! Not ready to go electric yet