PDSIT issue
Posted: Tue Feb 17, 2009 3:14 pm
I've been looking at a van of a forum meber of JustKampers forum as she has had all sorts of problems with her UK spec T25 2L aircooled van after a so-called "specialist" rebuilt her 2L aircooled engine.
Her problem was that it wouldnt idle and the top spped was about 40 mph. I said I'd go and have a look and at least go through a few simple things.
first thing I spotted was 3 inches of slack in the throttle cable, the linkage was very sloppy too with the roght hand ball socket missing the plastic socket in the linkage cross bar. These were simple to sort out of course.
Next was that the engine was shaking horrendously on idle. Its a hydraulic tappet engine, and presumable the idle was just so low, the tappets werent pumped up. The central idling "hole" was hardly pulling any air - again easy fix and a couple of turns of the nut (not a screw strangely on these) and she was hissing nicely and the speed picked up, but still with quite a shake (could hear the H/Xs hitting the mounting bar!!)
Timing was at 30 degrees at idle??? took both tubes off the dissy, and it was still bad - adjusted to 28-30 max advance - sits around 10 at idle with hoses off. Put retard hose on, and its at about 3 ATDC - OK. Put advance hose on and its at 25 BTDC. odd. lower idle speed, still have vacuum on advance line.
So have removed (temporarily) and blocked with screws both advance and retard lines and she is running around without these at the moment. Witht he lines on, the idle stabilizing unit is working overtime changing the idle timing, and this I think is part of the issue with the VERY wobbly engine. With hoses removed it revs fine and idles smoothly.
However, the top speed is still apparently around 50 mph. The distributor is advancing fine on the centrifugal advance, so this should be fine for 60-70. I'm thinking maybe fuel delivery is impaired? Maybe the engine has been damaged by running around in such a state previously. I'll do compression readings next time I go around.
I'd also like to set up the carbs properly. There should not be vacuum at idle above the throttle plate. I'm guessing the "engine Builder" has turned off the central idling circuit as much as possible and was trying to get a decent idle speed by using the throttle stop screws on the carbs. What is the right sort of base-setting for the throttle stops? Am I on the right lines here?
I get very angry when people get ripped off like this, and I'd like to get this sorted for her, as she is not a rich person, and it seems the builder is doing more damage than good.
I'll check the fuel lines, filter and rate of fuel supply too next time I go over it.
Her problem was that it wouldnt idle and the top spped was about 40 mph. I said I'd go and have a look and at least go through a few simple things.
first thing I spotted was 3 inches of slack in the throttle cable, the linkage was very sloppy too with the roght hand ball socket missing the plastic socket in the linkage cross bar. These were simple to sort out of course.
Next was that the engine was shaking horrendously on idle. Its a hydraulic tappet engine, and presumable the idle was just so low, the tappets werent pumped up. The central idling "hole" was hardly pulling any air - again easy fix and a couple of turns of the nut (not a screw strangely on these) and she was hissing nicely and the speed picked up, but still with quite a shake (could hear the H/Xs hitting the mounting bar!!)
Timing was at 30 degrees at idle??? took both tubes off the dissy, and it was still bad - adjusted to 28-30 max advance - sits around 10 at idle with hoses off. Put retard hose on, and its at about 3 ATDC - OK. Put advance hose on and its at 25 BTDC. odd. lower idle speed, still have vacuum on advance line.
So have removed (temporarily) and blocked with screws both advance and retard lines and she is running around without these at the moment. Witht he lines on, the idle stabilizing unit is working overtime changing the idle timing, and this I think is part of the issue with the VERY wobbly engine. With hoses removed it revs fine and idles smoothly.
However, the top speed is still apparently around 50 mph. The distributor is advancing fine on the centrifugal advance, so this should be fine for 60-70. I'm thinking maybe fuel delivery is impaired? Maybe the engine has been damaged by running around in such a state previously. I'll do compression readings next time I go around.
I'd also like to set up the carbs properly. There should not be vacuum at idle above the throttle plate. I'm guessing the "engine Builder" has turned off the central idling circuit as much as possible and was trying to get a decent idle speed by using the throttle stop screws on the carbs. What is the right sort of base-setting for the throttle stops? Am I on the right lines here?
I get very angry when people get ripped off like this, and I'd like to get this sorted for her, as she is not a rich person, and it seems the builder is doing more damage than good.
I'll check the fuel lines, filter and rate of fuel supply too next time I go over it.