Anybody using msd in old formula , wiring
 

Currently have msd distributor and 6al box but tach doesn't work . I have 2 purple wires and 1 grey on the motor was wondering if I should have 2 grey wires ? Have the red wire on the box hooked to the purples and the grey wire on the box to the grey on the motor . Tach itself may be bad just looking for ideas thanks

Normally there are 2 wires on the (-) of the coil, one to the tach and one to the thunder bolt ignition module. I don't know how your setup now, but the wire from the tach needs to be on the negative of the coil.

Other threads talked about hooking the grey wire to the msd box but no definite answer coil would be worth a shot , probably wouldn't hurt anything ....

Where is it hooked now, to the block? If do you do it won't work, I think you should put it on the - coil

Grey is currently hooked to the tach wire coming out the msd box but no tach reading

Tach wire goes directly to the 6AL box. There's a recessed male spade output terminal.
No tach wire to the coil in this application.

Ok so tach must be bad anyway to test it ?

No, you may need a tach-a-dapt made by MSD

My tach gauge is original to the boat 88 year , I thought the adapter was for newer guages ??

I don't really know. I'm no expert. It has something to do with the trigger signal. I have had 2 boats where I installed complete MSD systems. Both boats I owned and ran before the installation. So, I knew the tach's worked before hand. My first boat after the install the tach's did not work. Installed the tach adapters and they were fine. My present boat the tach's worked after the install!

Which tach adapter did you use there are a couple different ones from msd I'm just running a carbed motor ?

I believe it is the 8920. You certainly could call their tech

Sorry, it was a long time ago. However, I just googled MSD tach adapter. The one I used was definitely the physical shape of the 8920. So, I am pretty certain that was it. Again, call them!

If you can, I would ditch the MSD system completely, and use a Merc TB-IV distributor and a V6-14 module. I'll be that's where some of your top-end running problems are coming into play.

The Merc TB-IV is just about bulletproof and very simple.

You have to be kidding with that statement!

I doubt he's kidding.

MSD has a well deserved reputation for being problematic and the thunderbolt has a track record of being relatively problem free.

Please. First of all he says "I'll bet that's where some of your top-end running problems are coming into play". Where and when was that ever mentioned. And the MSD being problematic. Seriously, many, many thousands have been sold and their defect rate is probably better than most. Parts break.......auto parts, coffee makers, whatever. Truthfully, I put the MSD system on my present boat because the thunderbolt distributor and V6 module were acting up. I'm not bad mouthing the Mercury part.

Yes, seriously.
I've had two boxes quit and a distributor that corroded beyond operation.
No thanks!

Well, I'm sorry to hear that, but I'm not sure that makes for a bad product overall. Here's 2 of us talking. You had a bad experience. I have had a good experience on 2 boats. As I said I had 2 systems on my first boat that were trouble free for the 5 or 6 years before I sold it. The 2 systems on my current boat have been fine for that many years as well. What can I say?

Curious in this application what the msd box does that a thunderbolt iv cant? Rev limiter?
A few years back I went with a pertronix distributor because i needed more initial timing without more total as well as the total coming in quicker and have been very happy with it. But I've never had an issue with the thunderbolt and have used v6 modules where more initial is needed.

Exactly.

Hey take it easy! The op and I have been talking regarding issues he's had with his 525SC hence my comment. Initial timing plus a limited amount of advance for the blower can make for a hard combination to figure. He's been having a hard time so I suggested something that is quite tried and proven. The TB-IV setup with the V6 module (properly grounded if I may) is darn good for what he's doing. I'm making 600 HP with a tired blower on that setup, and it will support a heck of a lot more.

As for MSD... don't even get me started. So much trouble with my drag car stuff. I wouldn't want that kind of unreliability in a boat setup.

I will say that it's interesting that MSD sets up the 6M to be able to be bypassed (and run solely off m the TB-IV setup) if it should fail. A clue?

I was dead in the water once with a 6m. Just smoked itself for no apparent reason coming up on plane. It was in an '89 242. The tach never did read right even though there was a tach adapter. I'm pretty sure it was correct at idle and wot but the middle was tempermental. After the blue box cooked itself I installed a 6al and pre wired a chevy hei unit just in case it happened again.

you are correct you need to install tach adapters most all vdo gauges need them

Sounds exactly like my car...

Sounds like a battle brewing with no winner. There is no question there are MSD haters. I'm not sure how to defend the company or why I even care about defending them other than to say what I said earlier. They sell thousands of units and have been in business for as long as I can remember...........probably 40+ years. They are the biggest in this segment which actually can work against them. Let's say for example a company sells 1000 units and gets 100 back supposedly defective. That's 10%. A smaller company sells 100 and gets back 10. Still 10%. I am going to guess the odds are a lot greater the internet will hear from that group of 100 saying what a piece of crap they just bought. Actually use the same example of 10%. The group with 100 defects has 10 people complain, 10% and the group with 10 defects has 1 complain, 10%. Which sounds worse or more convincing 10 complaints or 1??????????

I'm not an MSD hater. But I do believe that their quality has gone by the wayside over the last ten years. Do they still work well? Yes, when they work. I still use their products on my car, but I don't rely on that car to get me back and forth from anywhere (I do drive it limitedly on the street). Do I want those parts in my boat? Heck no! I like being able to get back to shore. I don't trust their products enough to safely get me back to the dock. Corrosion and moisture are big issues with MSD (a Google search will show plenty of hits on this). Quality was a huge thing for MSD and it was rare to hear of anyone having problems with their parts. Not so the case these days.

On the Cig that we run, we do in fact use MSD 6M boxes in conjunction with the TB-IV ignition (and a V6 module... MSD is used to help with idle with the blowers), but those boxes are well over 15 years old. The point is that back then their quality was better. I cannot say that about the new stuff.

One more thing to add... The Digital 6AL that's on my car now has worked very well. I've had no issues with that box (it's unfortunate that it's not available for marine).

Seems like it's just you and me right now in this discussion. I don't want to be bashing you. However, look at what you just said. "Do they still work well? Yes. You use it on the Cig........seemingly without issues because they are older versions! And you do use a 6AL on your car and it works well". It sounds like you like MSD to me, but have a preconceived fear of today's product in the marine world. Whatever!

We just ran into this problem yesterday...was told to get #8910 modules??

Edited my statement since you called me out on it.

Yes, they work well, when they work.

Look, with my car, if it breaks down, I put it on the trailer and go home. Not such a big deal. I don't drive it more than bout 20 miles from my house, and being off on the side of the road isn't a safety issue. Can't say that with the boat. Being stranded a few miles offshore is not something I wish to experience. Can it happen with the Merc stuff? Sure! But it's less likely.

Enough arguing about it. We both have our own opinions.

Yep. That's the tach adapter.

Well I will try the tach adapter , may also switch to tb 4 in the spring . Tom I'm going to rebuild the carb also !