Reading through some recent postings, I notice some people don't know what (non) interference is. Well, it's to do with what happens if your timing belt fails.
As the engine continues to rotate, but with the belt bust, the valves are in their last open-closed state. As the pistons rise, they can strike the valve if it INTERFERES - bad news as that usually results in mucho dollars to fix.

If the valves are receeded, even when open, the piston rising does not strike and damage.

:)

Best though, is to replace the belt at latest as per spec, or more often - its cheep and not too diffiult.

:)

thankfully the V6 Volvo engine [from 1975?] does not seem to have a problem with timing chains, at least it seems from the fact the old engine in my 264 must have been 5 times around the clock and only failed because owner put water in cooling system

when I lived in UK in same period I bought a 1972 Triumph Stag V8 and the owner claimed it had a brand new engine and showed me the paperwork from the dealer that did the job and it said "supply and install new engine and replace bonnet"

The interference had apparently blown one head right up into the bonnet

I brought the car back to Oz and during that short time I owned it I replaced the timing chains just to be sure

I also bought a 1972 V12 E Type and while both these cars were far sexier than good old Volvo there is no comparison at all in the engineering

like Stag was made for USA market and it was said you would see them all over the States [by the roadside with bonnet up] - a great pity as the concept was great