[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [New Search]
On 14 Oct 2003 at 1:16, David V.N. wrote: > AFAIK,Heather is a stock 1969 D-Jet.Some PO has removed the cold start > stuff ,(valve,relay,etc) but aside from some taped off wiring,seems > complete. That sounds fine. > I followed the values that are listed on the page for 0 280 100 049 MPS. > That #,though not stock,is what was installed on the car when I got it. > It ran fine before so I used those values as a start.It got me in the > ballpark. Incorrect PS are often found on these cars. It's impossible to say why, but my guess is that the reasons are varied, and include, "It's what I had," "It's from a Porsche, so it gives me more power," "This is the later one, so it must be better," and "They're all the same; there's really no difference inside." When I find stuff like this I like to inspect all the parts to try to find out what else has also been changed. Sometimes you find a car which has been changed to a completely diffeent, but consistent system. Jim in Chicago, for example, has a 69 with a complete 73 FI system. That will work just fine. But the wrong PS isn't likely to give you overall good results. What the PS actually does is measure the absolute pressure in the intake manifold. It does this in relative units, which the brain is calibrated to understand. If you use a different PS then you have potential problems on 2 fronts: the relative units can be different, and the pressure drop between the manifold and the combustion chamber can be differen. While there must certainly be combinations that work just fine, you are probably more likely to find ones that don't, or that seem okay, but cause some not-too-noticable problem that might really be important. An example of the latter would be an engine that is running too rich. This may not seem like a problem, but the reduction in gas mileage costs you money and unnecessarily pollutes the air that we all have to share. Excessive fuel also washed down the cylinder walls and causes rapid ring wear, and dilution of the engine oit, leading to a short lifetime for the engine. Engines that run too lean usually don't run well, so they get fixed, but engines that run too rich are usually perceived as running strong and left alone to die an early, but unexpected death. So, the obvious question here is, "How's your gas mileage?" > It is stated there that an eight of a turn makes huge changes,You can take > that as gospel! When it would start,I tweaked it,by ear at 2500rpm,to > smoothest running.After a very small amount of back and forth adjustment,I > think I hit a "best as I'm gonna get without a CO2 measurement" point and used > cyanoacrylate to lock it in.Been running like a little bear ever since. I'm not sure, but I think there is one more factor that (I'm not sure about this) this web page did not address. I believe that movable part of the magnetic core within the PS was machined to different shapes for different cars. At least if you look at one you can see that it is a tapered spindle that could easily be varied in taper to create differently shaped response curves to match the needs of different engines and brains. This would mean that you might be able to match up 2 different PSs at one vacuum point, but that still wouldn't give you a good match anywhere else. > As far as the dizzy,you are correct,it is AXIAL play.(I always confuse the > two.) Just shims to adjust,isn't it? There are both shims AND it is also possible that there is a little snap ring and/or washer missing, down under the felt pad at the top of the shaft. If the upper shaft will move up and down a lot while the lower one is held stationary, then the snap ring/washer is the problem. Note also that there is supposed to be a small spring under the distributor, in a recess in the top of the dist drive gear. If this spring is there, then the dist shaft will always get displaced upward to that end of its play. The play itself is not a problem as long as the shaft position is consistent. If that spring is missing, the shaft can bounce up and down and produce erratic output. -- Jim Adney jadney@vwtype3.org Madison, WI 53711-3054 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ List info at http://www.vwtype3.org/list | mailto:gregm@vwtype3.org