ashlock tach adapter set switches

[juanbenae]

ive PM'd Bob Ashlock on this earlier today and to this point I have not heard back from him understandably having it only been a couple hours but was looking to button up my CDI mounting effort. particulars-- early 3.oL motor with MSD AL6 CDI box, pointless dizzy into a 75 chassis with the original silver dot tach.

the unit comes set at the 1 & 5 positions where "no change in rate" for the signal. am I to leave the switches in these positions, or will one of the other selections that declare six engine cylinders but refer to 4 or 8 tach cylinders?

I have already declared that the number on the back of the tach being a "1" and not a "C" necessitates the jumper to be removed from the unit.

any insight would be appreciated

t

[juanbenae]

for future searches,,, I was over thinking this.... the 1-5 combo was correct as I was not changing the number of cylinders or the intended tach.. duh! the other settings are if you are using an 8 or 4 cylinder tach with a 6 cylinder motor.

makes perfect sense now after walking the dog and thinking on it some.

early mock up

[Mahler9th]

Happy New Year!

Looks like a nice mounting arrangement, similar to those i have fabbed up.

Cannot answer your question... but I have used MSD 6A and MSD 6AL units for years with an SC-styled distributor and either a factory VDO (probably from a 2.7 car) or an AutoPower Tach. No adapter device necessary.

My Autopower tach is a #6811. No use for it any more with my AIM Gdash.

Similar set ups from the same engine builder have also used this tach or similar, with no adapters in the signal path.

What does that extra little box do and why do you need it?

[juanbenae]

hey mike, happy, long dreary, rainy winter to you too! hope no dams near you are failing.... ive been good. pretty sure I told you sold the turbo when I saw you at the P@P event last October?? since then ive acquired a 75 that was purchased with somewhat known basket case early 3.oL motor in place but has gone to full basket case.. getting thru it though with the help of the boys at RMG.

the lil box is the noted tach adapter developed by mr Ashcroft here on pelican. the MSD would likely not likely drive the early tach that's in place in the 75 chassis & wiring harness. easier to do now then find I needed it after the motors back in. nto really interested in an after market tach as the current silver dot is what made me love 911's back in the day. here's the interior--

I wanna keep it as is.

also looking for info on the rewire of the dizzy connection from the MSD. does violet go to the right side jack on the two prong fitting, or does the green. the OE Porsche wire is the duplex stranded and mine is a mess. what do you know on that?

[Mahler9th]

My factory VDO tach is a '75 (so is my chassis) and I drove it directly from MSD 6 and 6AL products with no issues. I can send you a simple schematic, or post on here.

[juanbenae]

my tach carried the "1", not the "C" on the back where the wiring spades land. according to my research this unit required the adaptor. build date is 9/74, so it's an early bird 75S.. PM or email if you wanna stop by & do a walk around. be good my friend.

[Mahler9th]

My VDO is actually date coded 5.1976. My car is a racing car based on a '75 with a hodgepodge of parts.

I started out with a single MSD 6A/MSD 2 Blaster Coil, and later ran MSD 6AL/Blaster 2 coil. I started with the factory VDO tach date coded 5.1976, and later to an Autopower #6811 tach. Direct connection from distributor little green wire to MSD magnetic input, and from MSD tach output to each of these tachs. No issues.

I am not an expert on which factory VDO tachs work with MSD, with MSD tach adapters or any of that.

The pinout I use from the little green wire to the MSD magnetic input is shown in the picture below.





I run a short cable that mates with the little green connector on the distributor side, and with the MSD mag input wire connector on the other side.

MSD sell a connector kit I used to make this short cable.

Pictures below.







When I switched to twin plug in '15, I maintained this scheme. My friend/engine builder modified a 993 distributor to facilitate this, and this set up maintains use of the little green wire. With my current set up I use twin MSD 6AL's which are daisy chained, and twin MSD Blaster 2 coils.

[juanbenae]

thanks mike!

this is the money shot!