Stock tach on MSD

[Rickdees]

Ok, I've read that 4 cylinder tachs the RPM reading will double if you run it on a V8 and a 6 cylinder adds 2/3rds.
I am running the MSD magnetic trigger and using the green and violet from the box and the manual says to use one of these
http://www.summitracing.com/parts/msd-8920
they say this: If you are using the magnetic pickup input (green and violet wires) to trigger your MSD Ignition, you will need one of these tach adapters. These units will correct the operation of most voltage-triggered tachometers that do not work directly off of the tach output terminal of your MSD unit.
"But"
Our tachs will run from the tach plug off the MSD box, it just reads more then the actual rpm's if you have more cylinders.

Question:
Will this MSD Tach adaptor run my RPM's correctly?

[Fordubishi]

No you cut the looped wires to make the trigger for a 4 or 6 cyl. Check the MSD site they have the instructions.

[Rickdees]

I read that, I'm assumed my son's mechanic/wizard friend had done that. That's only thing I did not do was hook up the MSD.
Thanks I will look.

[pennyman1]

I ran an MSD 5 series and never had an issue with the tach reading being doubled, but I also know a 6 series is different than the 5 series.

[Rickdees]

Yeah I read on other forums about the tachs. They're using diodes to change the readings. I'm not one of those guys, I'm boilermaker/Ironworker so I'm clueless about electronics. @ 60 I'm running about 3700 on tach but in reality 2500. After unmounting and opening the MSD box I read the manual again and it says to trim the wires on the MSD 6AL, 6BTM and 6ALN, the 6A does not need any modifications to run a 4 or 6 cylinder even fire engines. 4.3 is even fire(3.8 odd fire).
I could just buy a tach, but want to run in the stock. I need to call MSD, I have tach adapter 8910 which is wrong, it uses the white wire for HEI or points. That link I posted with that adapter 8920 runs out of the tach plug to the tach, For now I'm stumped?

[Fordubishi]

You running a 6A or a 6A digital? I have the 6A digital and it says cut the one of the loops (blue or red) for 6 cyl, Cut 2 loops for 4 cyl.The 6A says cut the red wire loop for 6cyl. I used a 6A on an 89 S-10 with the 4.3L and just cut the red loop and the tach read correctly.

Also remember the tach in your truck was for a 4 cyl and even with the wire cut your tach will see 1/3 more reves as you're sending a V6 signal to a 4 cyl tach. You can send your tach out to get reprogrammed but that would cost more then getting an after market tach.

so your tach seeing 3700 as a 4 cyl if the tach was for a V6 you would be seeing 1/3 less.so 3700/3 = 1233, 1233X2(correct V6 signal) would be 2466.

[Rickdees]

It's has to be a 6A, the day after I bought mine the digital came out. It's just my luck.
I don't see anything like what is described.
I've got the new magnetic trigger but before I took the old one out I tested it again with the distributor out and it is firing. I don't have the balls to hold my hand as a ground, I've been hammered by this bastard before("Oh my"). It's seems like it goes dead at the distributor cap with no fire or as it turns over it goes dead?, the plug wires are in great shape
Just how far out it will or should jump to arc is unknown? (but I'm at about a 1/4").
Process of elimination does get expensive. At Summit the magnetic trigger is $25, here at the auto parts store it's $38.

[Fordubishi]

Ah I see whats wrong the 6AL needs the wire cut, the 6A doesn't have any wires as its doesn't have the rev limiter. So what you need to do is either get your stock tach reprogrammed for a V6,or use an after market.

In the instructions at the top it says the 6A,6N and 6TN do not need any modification to run 6 or 4 cyl as you stated. Sorry about that.

[BradMph]

I hate to see Fordubishi disarming a bomb, red wire...No blue wire, No red wire....Clip....KABOOOOM!
6147

[Fordubishi]

should see me trying to light a BBQ..............