MSD ignition on '68 912

[wkrtsm]

Did some research, and made a lot of tech support calls before pulling the trigger on an MSD ignition - specifically the 6A. Didn't get the 6AL (w/rev limiter) since I don't do track, kids don't drive the car, and never find myself in the position where the pedal is on the floor too much and at risk of popping out of gear, or downshifting into first when I'm doing 30 or 40 MPH.

-Also purchased:

1). High Vibration (black) MSD Blaster Coil, since the Bosch coil won't work.

2). MSD VW Billet distributor and MSD VW Type I 8.5 mm wires. Since I have a ’68 912, I got stuck with a Bosch 009 distributor, which is a Brazilian-made VW distributor with a horrendously terrible advance curve that seriously degrades mid-range RPM torque pulled out of the 912 engine. The much better Bosch 022, 031, and 050 distributors came on 1967 and earlier, and are rare and quite expensive if you want to purchase one. Specifically, the 022 came on 356C and 912 through 1967; the 031 came on non-US delivery late 1967-69; and the 050 is a linear advance replacement that wasn't designed for 1600 356/912 engines. The used 022, 031, or 050 distributors I found online looked like dog-meat, were in pretty bad condition, and cost more than $500 unrestored. If you did pick up one of these, by the time you paid to have it restored, the total cost would likely be ~$1000 -- just to get away from using the 009! Given this, the best alternative for me was to buy a new MSD VW billet distributor for ~$300, since fit-wise it’s the same as the 912 distributor dimensions – like I said, the 009 is a VW distributor. The MSD VW billet distributor has a wider cap width of 3-4" and larger post separation, which is beneficial if you had crossfire. But CB Performance said you'd only get crossfire inside the cap when using an MSD and Blaster coil if you were at or above 8000 RPM. Thus, CB Performance and MSD both said a lot of drivers use their existing distributor (rotor & cap) – again, I only purchased the MSD VW billet distributor to get out of using the 009. The only thing good for using a 009 is if you drag race VW beetles or vans and do hole shots at the gate at 4000 or 5000 RPM.

Setting the advance on MSD VW Billet distributor. In the reply post below, attached is an image of one of the advance curves that can be set on the MSD VW billet distributor, by selecting various spring colors and size, which are shipped with the package. This one is similar to the 022's advance curve, however, it kicks in above 1000 RPM and cuts off a little above 3000 RPM. The advantage of having a shallow advance slope below 1000 RPM is that after revving, the idle RPM can equilibrate to a steady-state better, whereas if the steep advance slope extends below 1000, you can have idle issues. The slope also seems a little non-linear, just like the 022, which apparently provides more torque in mid-range when compared with linear. Be aware that the x-axis on an advance curve is in units of distributor RPM, not engine RPM.

3). NGK 3725 BPR8HS standard spark plugs. MSD recommends standard copper plugs that are one to two levels cooler than OEM. Rationale for using standard copper plugs with MSD is because they can take the additional heat. All plugs have a copper core, but the newer iridium tipped, platinum tipped, and laser 4-point tipped plugs burn up too fast according to MSD. My 912 tech manual states that Bosch WR6BC are OEM, so I searched for the cooler WR5BC+ and they were discontinued. So I went with 8-level NGK 3725 BPR8HS plugs (heat scale is opposite of Bosch - higher is cooler, for Bosch lower is cooler; the BPR7HS cross references to WR6BC, so the BPR8HS is one level cooler). Regarding spark plug gap, the internet is filled with forum entries for drivers who claim using gaps of 0.040" to 0.060" with MSD. However, MSD tech support recommended not adding more than 0.005” to the OEM gap settings for 1600 cc VW/912 type engines, since opening gap puts additional (unnecessary) load on the system. In addition, CB Performance said not to use more than a 0.030" gap for a 1600 cc with MSD, or you'd be inviting problems.

Last, MSD acquired Mallory in 2005-2006, and did continue to manufacture some items, but didn’t continue production of the Unilite distributor which worked in 912s. The only Unilite distributors which could be found online at the Mallory page at MSD were for GM, Ford, and Chrysler. I think the newer MSD VW billet distributor is a knock-off of the earlier Unilite for VW.

[wkrtsm]

This is one of the advance curves shown in the product insert of the MSD VW Billet distributor, which can be selected by using a specific spring combination. This particular one is close to the advance curve of the 022, and is based on use of small blue and small silver springs. (this is the curve I selected for my 912 engine):

[wkrtsm]

I also found this advance curve for the 009 distributor.

[wkrtsm]

The VW 009 advance curve above does look like the curve that appeared at the Rennlist discussion, which has a linear slope after about 2500 RPM (distributor RPM).

[69porsche]

I have no idea what the graphs mean, but I am sure your car will do just fine!

[wkrtsm]

Thanks - the curves just mean that, as RPM increases, there's less time per crankshaft revolution, so the spark has to fire earlier (before TDC) on the compression stroke. (like shooting a moving object, you have to lead more when it's faster). This is done by moving the spark time earlier via degrees before TDC. The greater the RPM, the earlier the spark has to fire. The charts just show that for higher RPM's, the advance degrees is greater. The problem for the 009 is that it doesn't advance over the RPM range about 1700-2400, so you lose significant power. In other words, it does nothing from 1700-2400.