Hi I have a 63 3.8 coup I, try retensioning the the top cam chain first .if the noise persists then move to the lower chain ,you have to ascertain why the chain is loose , is it because the chain is phyically worn ,or is the hydraulic tensioner not working as it should ie blocked filter inside the tensioner have the chain guide shoes come loose .This is just a brief outline may be it will saby Gary Percival - Jaguar E-Type Forum