Howdy gang,

As some of you may recall, I've had a rich condition plaguing my poor little 63 PV for several months. I have a very slight vacuum leak around the throttle bushings which will have fixed soon....but that would tend to make it run lean anyway....but I had another thought to run past the experts in this forum.

The car sat for several years before I got my hands on it. I'm wondering if a semi-clogged muffler or silencer might be wreaking havoc with combustion?

Or am I grasping at straws?

If the exhaust system is restricted it will have real trouble at high RPMs.

How are your air cleaners?

I had a Mini in 1964 that died on the highway because the air cleaner was clogged.

This was when I was driving home from a tune up at a Shop that specialized in British cars!

Try taking them off.

When I bought my 544, the owner changed the oil and did a tune up - he told me that he had adjusted the carbs by 2-1/2 turns.

When I got home, the plugs were black. I called him and he told me that he was unshure if he adjusted the carbs in the correct direction - 5 turns later, the plugs got clean and it is running fine 8 years later.

A clogged exhaust can certainly effect performance. However your assumption that a vacuum leak could not account for a rich condition is not correct. A slight vacuum leak at idle will lead to a richer mixture being set initially to attain a decent idle and good step-off. Once at speed that vacuum leak becomes less of a factor but the jets are set at too rich a level than would be otherwise required. Fix the vacuum leak and then see if you still have a problem. -- Dave

Installed new rotor, cap, wires, plugs and new air filters. Timing is at 17 degrees. Valves adjusted to spec. Rather than continuing to chase this Gremlin, my last resort is to rebuild the carbs.

I could probably do it myself, but would rather turn it over to an expert due to possible machining of the bores. I've read good things about a company in Kansas (SUCarbs.com) and Island Automotion. Anyone have any comments about these company's? or is there another recommended company anyone has used?

Thanks.

I had my SU's rebuilt by Island Automation. Great job!

"Timing is at 17 degrees."?

At what revs and under what conditions? That may be your gremlin. Might be OK at 1500 rpm as a basic setting but may need tweaking a bit. I know you are blaming over rich carbs but they say that most carb problems tend to be solved by sorting out the ignition and timing.

Did you fix the vacuum leaks?

That Island place looks like they do good work. Heard good things about SUCarbs.com, too.
--
Tony - 1958 Volvo PV444, 2012 Volvo XC70 T6 Polestar

Sent the carbs in earlier this week to SU carbs. Due back in about 2 weeks.
I cleaned up the intake manifold and linkage. Installed new firewall grommet too. Shore does look purdy with all the bright shiny pieces!

I've had many sets done by Island Automotion, and they've all come back immaculate.

IF you are in direct competition with "rice burners" I would recommend rebushing the throttle shafts if it is REALLY a problem,if not, allow a bit of a rough/choppy idle so that at normal driving speeds the engine is happy.
I have dealt with old cars for at least a couple of weeks, and I have found that you can chase little gremlins that are not "life threatning" to your engine. If you have the money and time,etc. absolutely chase this "LITTLE" gremlin dowm and nip it in the bud. Bottom line I think is to have fun with that old SWEDE...ENJOY. Do not obsess on little stuff. Enjoy the car for what it is. Have fun !!!!

Yeah, I would say that vacuum leak MUST be fixed before you can diagnose any other possible conditions with the fuel system. However, I doubt a clogged exhaust would be the cause of your symptoms.

Vac Leak first...then further diagnosis.

Good luck!
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Tony - 1958 Volvo PV444, 2012 Volvo XC70 T6 Polestar