I plan to replace my plastic secondary chain tensioners which are overdue.
My question is should I also replace the head gaskets or whatever gaskets in the process, so as to prevent any oil leaks? TIA gents

 

I expect you mean valve cover gaskets.It may not be absolutely necessary, but I replaced mine because I didn't want to go back later.

Note that you will need the more expensive AJ26 gasket set, not the FelPro set that fits the later engines.

 

My guess is you mean valve cover gaskets/ seals in which case the answer is good practice would say yes. You will also need a small amount of high temp RTV where the timing chain cover joint is. Most importantly do not over tighten, use a torque wrench and follow the tightening sequence. The covers are plastic and easily warped.

 

Thank you guys, you're absolutely right, they're the AJ-26 valve cover gaskets/seals. I'll definitely change them on my 18 year old XK8 whilst replacing the 1st gen plastic secondary chain tensioners.