THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

I just finished my annual engine inspection and tune-up, but the Pinz isn't running as well as it has. I inspected and gapped the plugs, replaced the fuel filter, checked the cap and rotor, adjusted the valves, adjusted the timing 10 degrees at 900 rpm (Petronix), inspected the brass idle screws, and balanced the carbs. It seemed to be running fine, but once I replaced the air cleaner cover and restarted to double check the timing, the RPMs dropped to 700 and it started running rough. It is also hard starting, which was a problem just before the tune up. I did the carb balance again and double checked that both carbs were opening at the same time when the throttle was pressed, and upped the RPM a little.

Once I replaced the air cleaner cover I could get a rough idle between 800 and 900 rpm. One other mystery is when I close the brass idle screws completely there is little drop in the RPMs. The truck ran great up until my recent move. I was at sea level and now am at 1700'. I didn't think this was enough of a climb to affect the truck, but I leave it to the experts.

Any help or advice is appreciated.

Did you forget to tighten the distributor after your adjustment?

No, and double checked.

I brought that up as its something I did once. Caused mayhem.. Beyond that, there are so many variables that it's difficult to suggest a solution.

Air filter correctly mounted?

Carbs tight? Tight to manifold, base tight to center section, top tight to center section? Putting the air horn on should not affect the idle or performance, UNLESS there is some restriction in the horn and/or filter assembly.

1700' elevation difference should not be noticeable IMHO; I have driven over 11,000' difference and this does make a difference, but your small variation should be invisible.

Thanks for all of the advice. I checked the carb bases and they were fine. I replaced the rotor and cap, which looked fine on first glance thought the rotor needed a little cleaning up. New parts did the trick.