Quote:
Originally posted by Early_S_Man:
The coil or CDI-unit can't make the tach. act eratic! Older tachometers of 1969 vintage used a ballast unit -- a Voltage divider from the coil primary winding, but that was discontinued
|
Hmmmm, Warren may have answered the question I have had for a couple of weeks.
I installed an MSD unit on my 69 and the tach doesn't work when connected to the coil (as it was) - the multiple sparks of the MSD make it show 2500-3000 revs at idle!
The tach also doesn't register if connected to the MSD tach output or the distributor. Matt Smith installed an MSD in his '72 at the same time and it works fine from the distributor - therefore I have assumed the tachs are different from '69 to 72.
Warren's remark seems to back it up.
Best bit of news is the MSD tach adaptor is in my father's hands as of this morning and I can install it this weekend! Woohoo - working tach!
And Sunroof, sorry to jump on your thread. I have read that bouncing tach can be either battery or grounding issues or points. If it happened all of a sudden it is probably not bad grounds (which would worsen over time).
------------------
Cameron Baudinet
1975 911S (in bits)
1969 911T