MSD 6AL-2 '81 308GTSi

Hello everyone,

Quick intro: Bart, 35yo, 1st time Ferrari owner.

Recently I traded my RHD 911SC for a Yellow LHD 308GTSi. The Ferrari came with "work" and I'm converting it from US to EUR look. (bumpers, mirror, etc.)

It runs, but backfires like crazy and I can't get it to work with the current digiplex+non-programmable MSD set-up that relies on distributor/digiplex to take care of ignition timing/curve.

So: I decided to invest in 2 MSD 6AL-2 units which can be programmed with a laptop. Does anyone have the standard ignition curve for me to use as a starting point? Any other top-tips?

Cheers!
Bart

 

Question: Do your stock digiplexes work? I had mine rebuilt by Ferrari of New Bedford MA. Used new SEN8d pick ups, new wires and plugs. World of a difference. I was going down the same road, glad i didn't. Just saying... Wayne

 

I think you mean Ferrari Service of Bedford in NH. I've got a set of their boxes in my QV and they're top notch.

 

There were 8 curves programmed into the Digiplex's and the curve in use was selected based on coolant temp and manifold vacuum.
In general it ran from 8 degrees ATDC to 45 degrees BTDC.

 

Hi Guys, sorry I forgot to check back for replies as I got caught up in the repairs. In the meantime I've got the MSD's up and running, but there are more issues like bad connections, bad sensors etc. we decided to re-wire the whole ignition to be sure.

8 curves! We've got only 1 curve in the MSD's, any chance you know where to find those curves?

 

8 curves? ok but no aftermarket system can replicate that right? might have made a bad call in that case... any chance you know where to find those curves?

 

Fwiw. Many hi quality engine management systems can greatly exceed the stock number of ignition curves. The question is how many you will need for a normally aspirated engine. It can be difficult to properly set timing under all the load conditions, temps and other factors without a dyno or a lot of experience tuning. If done properly, you may see some gains over stock.

 

hello. i have the 6AL-2's too in the 308 gtsi. Could you help me with the curves? Is it possible that you sent me the file by email? [email protected]

the run retard curve does not go further then 25 degrees . And it should go to about 40 to my opinion. i have attached a pictures of the timing curve.
I hope you can help. thanks!
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The 6AL2 needs a retard curve (that is why I understand it for a change Lock out the mechanical advance (centrifugal and any vacuum) then set your distributor to give the maximum advance you want. Then put a dot at zero degrees retard at the (high) rpm you want to reach max advance and a dot at the rpm at which you want max advance minus 25 degrees. The curve will go up moving left to right (opposite of the curve above.) If you need a bit more retard for starting only you can use the start retard input wire (pink) to your starter solenoid.

Make sure you get your phasing correct so that the rotor is pointing at or or near the pole in the cap at all rpms (after the pole at low rpms and before the pole at high rpms.

This is something I still have to hook up. I am using the single distributor and the two sensors in series trigger the 6AL2 fine (see page 10 of my blog: https://www.ferrarichat.com/forum/threads/dereks-308-engine-rebuild.535247/page-10 )

 

"Make sure you get your phasing correct so that the rotor is pointing at or or near the pole in the cap at all rpms WHEN THE SPARK IS GENERATED (after the pole at low rpms and before the pole at high rpms."

If you remove the distributor cap, mark where the poles line up on the distributor housing, connect a plug and timing light to the coil's HT lead, rest the plug on something metal (to ground the outside), and point the timing light at the distributor, you will see where the rotor is pointing when it fires. It should have just passed the pole position at low rpm and will thus be just before the pole at high rpm. You may need to modify the rotor to have a wider tip since the advance is all electronic. I can't remember offhand how wide the twin distributor rotors are. With the mechanical system the rotor position is advanced and retarded in sync with the timing so a narrow rotor tip works fine.

It might be an idea to use a single 8cyl distributor and a single 6AL2. If you are going to compress your bumper shocks, check out how I did it with screw clamps-- easy and fully reversible.