Car Forum World

1968 Volvo with twin SU carbs on it has some a running condition.



Starts right up all the time engine runs good and clean during the whole RPM range and gears for ten or 15 minutes but starts to misbehave afterwards. Under heavy engine load it',ll start to make sound, kind of a cross between a ping and a rattle. If I don',t short shift or floor it the engine sounds perfectly normal and I typically only notice it pulling away from stop signs or accelerating to merge onto the interstate. I live in a hot area of the country and it typically runs between 210 and 230s F. Also after I turn it off the engine has a tendency to deisel or keep running for some seconds.Soooo I',m wondering what you think. it only has 72k miles on it and I',m wondering what to poke and hope it, I suspect it',s running rich and maybe the carbs have to be gone through. Runs rich detonating carbon on pistons deiseling but I dunno, but I',m open to suggestion before delving into the bad black magic voodoo of SU carbs

SUs may be a little cranky but once you get them set up properly they require nearly no attention. One thing that drives us old Volvo holders crazy is that the B18 and B20 engines were intended to run mainly on premium fuel, not what suffices for premium today but real premium fuel. The pinging you hear is just that but you may be able to get a good bit of it out of the picture by experimenting with your ignition timing. I now own three older Volvos, ',66, ',67 and ',69. None of them has the timing set to specifications and none of them are timed exactly the same.

There are some number of people around the country who rebuild SUs and do a great job of it. They',re not cheap but it could most likely be the only rebuild you',d ever need on the carbs, if you finally choose to do that. I',d mess with timing 1st. change your valves, then set up the carbs. The Haynes manual for your car has excellent SU modification information.