Knocking noise

[cleverusername]

Another day, another issue. After taking the car for a test drive up and down the drive it has developed a knocking noise at idle. I have tried to locate it but I can't hear anything by putting my ear to the usual suspects. This makes me suspect the bottom end is not in a happy state. When I rebuilt I fitted .20 oversized bearing, as they were the ones fitted to the engine originally. Didn't get the crank reground but it would be at the limit anyway and need replacing.

It revs up to 6000, didn't dare push it beyond that and there isn't any smoke but I don't want to push my luck and run it till I have checked it. So what is the best way if checking the crank for imminent failure?

[xvivalve]

Oil pressure?

Does the knocking change frequency with engine speed?

[cleverusername]

Oil pressure?

Does the knocking change frequency with engine speed?

To be honest it is difficult to hear it at much above idle over the exhaust noise.

I have taken the cam cover off and removed the sparkplugs. Had ago at putting a bar down the spark plug hole to see if I could get the pistons to move when they are at the bottom of their stroke. Can't feel any movement, however I am beginning to have doubts about the quality of the shim job I did on the valves.

So what I need is the idiots guide to how to setup the valves properly. At what position do I take the measurement and should there be any vertical play is the rocker arms? At the moment I can move the rocker arms up and down easily when both the inlet and exhaust valves are closed.

[cleverusername]

Just had a look at the workshop manual and if I am reading it correctly my valve clearances are way out. When no.1 is closed you're meant to measure no.3 exhaust and if that is right my clearances are hugely out, I can move the rockers, I don't even need to use a feeler gauge to see it wrong.

[cleverusername]

It turns out the valves clearances are fine, the problem being I trusted my father to read me the clearance numbers and he got the wrong ones from the book. The exhaust is set at .45mm, which is apparently OK.

Listening again the noise does increase with revs and matches the flashing of a timing gun attached to engine. My father thinks it could be oil starvation of the top end but I am not convinced.

[tony g]

which engine? I would close up the clearances 0.45mm is over 020 thou

[cleverusername]

which engine? I would close up the clearances 0.45mm is over 020 thou

I got the numbers from Sprint workshop manual, it list 0.46mm or 18 thou as the clearance for both inlet and exhaust valves.

[xvivalve]

It turns out the valves clearances are fine, the problem being I trusted my father to read me the clearance numbers and he got the wrong ones from the book. The exhaust is set at .45mm, which is apparently OK.

Listening again the noise does increase with revs and matches the flashing of a timing gun attached to engine. My father thinks it could be oil starvation of the top end but I am not convinced.

Run it with the rocker cover off and see if the rocker tips are pulsing oil

[tony g]

Yes under 20 my bad. I would run them 12 thou Ex and 8-10 inlet. No need for them to be that large really. As Alun says run it with cover off to check for oil.
Another trick is whilst running (if it makes the noise idling) is pull the plug leads one at a time and if the noise goes away theres a problem with that cylinder. HTH

Tony

which engine? I would close up the clearances 0.45mm is over 020 thou

I got the numbers from Sprint workshop manual, it list 0.46mm or 18 thou as the clearance for both inlet and exhaust valves.

[cleverusername]

Yes under 20 my bad. I would run them 12 thou Ex and 8-10 inlet. No need for them to be that large really. As Alun says run it with cover off to check for oil.
Another trick is whilst running (if it makes the noise idling) is pull the plug leads one at a time and if the noise goes away theres a problem with that cylinder. HTH

Tony

which engine? I would close up the clearances 0.45mm is over 020 thou

I got the numbers from Sprint workshop manual, it list 0.46mm or 18 thou as the clearance for both inlet and exhaust valves.

Tried the plug test and pulling the leads makes no difference, so I don't think it is the bottom end. I have terrible ear for them things but it does sound a bit like an old diesel at the moment. So it could be oil starvation to the top end.

[dollyman]

Does the noise change when you put your foot on the clutch?

Tony.

[cleverusername]

Does the noise change when you put your foot on the clutch?

Tony.

Nope, it makes no difference.

[dollyman]

Mmm, remove fanbelt and see what happens? To be honest it doesn't sound serious as i'm sure it would have gone bang when you took it up to 6K

Tony.

[xvivalve]

Which brand timing chain tensioner did you use?

[cleverusername]

Which brand timing chain tensioner did you use?

I think I got it from Robsport. We did have a look at the chain and it seems to be tight enough. Though I don't know if the chain can remain tight with a failed tensioner.