Hello everyone, I was wondering If you could help me out with tuning up my newly reassembled 1977 B21E (Australian model). We had the head rebuilt

It will start, but the idle is all over the place, surging up and down like its revving itself. I think this is just air leaking into the throttle body through various air hoses. I know the flam arrester lines need replacing, and the surging should just be something leaking, I should be able to find that.

What is more worrying is that it's running way rich and fouling its plugs. The fuel distributor has been reconditioned and set back to its original control settings so I know the FD is exactly the way it was in '77. The rest I don't know.

I can find and fix all the holes, and have a good source of pick and pull parts costing little more than pocket change, but twiddling and diagnosing stuff is confusing me

Can people please tell me how to test and tune my air fuel mix. The car is currently in an electricians workshop (my grandfather's bussiness) so I have the expertise on hand to diagnose electrical faults once we know what we are looking for.

Basically I would like everyone to tell me every reason they can think of for a volvo to run rich, and how you check for it.

Sorry this is so long.