and here's the complete cluster. i really did a bad job on painting the silver outlines. i guess i will never be a top notch pinstriper when the engine is back from rebuild i'll be hopefully able to adjust the tach. then i'll post one more shot of the finished product!
unfortunately, it wasn't as simple. tried to do the exact thing yesterday, with the engine running. a digital timing light gave me a pretty good reference. but the poti didn't adjust enough to get the reading down. i started off with the double reading - as the tach is made for half the number of cylinders. but the poti only allowed for minor changes. so i ordered the TachMatch mentioned in my first post. made by a friendly and helpful guy, he advised on how to install it with my msd 6a and the 8920 tach adapter i already have. as soon as it arrives i'll post some more updates!
The 150 ohm 1 watt resistor(the larger one) in this shot has overheated and could be out of spec, if that's the case may be the reason it won't cal... Also if we knew what resistors were in the circuit with that cal pot it may be possible to change a value and get it to cal to eight cyl specs... I've done same with '87-'88 Turbo coupe tachs but that one is considerably different...
ok guys, thanks for all the helpful comments. the tach is up and running! i did not doubt it was working in the first place - it was just way out of spec, showing double the actual rpm as it was made for a 4cyl engine. the poti can be used for calibration, but not enough to divide the shown rpm by two. so here's a shot of the tach match adapter installed, right between the msd and the msd tach adapter: tach match has a nice function for calibration - just use a little switch and it will put out a steady signal - 6k rpm in my case for a 4cyl unit. thus, i could easily calibrate it with the poti, and now it is working flawlessly. and it looks just awesome!
