Datsun Roadster Forum-311s.org

I was just curious, has anyone ever put a dual point distributor into a Roadster?

Interesting question if thinking about performance upgrade possibilities in the OEM period (through the 60's and 70's). My thought though is in this age if you are going to change from original, why bother with points at all, why not go straight to electronic? I don't know of much advantage of dual points over single, and most especially when compared to EI.

I haven’t thought or heard of dual points in many decades. As I recall the main advantage was control of point float/ dwell @ high RPM or bragging rights. Personally, I’m getting ready to order an EI unit this week.

Peace,
Pat

The 240Z with automatic trans was equipped with dual points ignition, but Nissan did so for emissions purposes rather than performance (controlling point bounce or spark duration for performance purposes).

Single point distributors running with an MSD (or other) 6 capacitive discharge box greatly reduce point wear. The amount of current going through the points is reduced to only about 5% of the stock current, so points do not pit or burn. Similar to motorcycles with point ignition, wear occurs only on the rubbing block (so keep a bit of cam lube on it). Gap is not critical, b/c the CD box requires only that the points open and close.

In the unlikely event of CD failure (or suspected failure), the ignition can be quickly returned to stock by only switching the spade connectors on two wires mounted on the coil. Having done a bit of spring cleaning recently, I ran across receipts for the MSD boxes on our SRL and in our Volvo inboard dated 6/1987 and 8/1993, respectively. Neither ignition has given us any trouble thus far.

This is offered not as an endorsement for MSD, but rather to encourage anyone considering an upgrade to the stock distributor to consider the advantages of running points with a capacitive discharge box before making a decision.

Jon

The purpose of the dual point distributor was to increase the dwell time and produce a hotter spark. With an electronic distributor like the Nissan match box the dwell time is huge which is why they put out such a big spark. The idea behind the big spark was for more complete combustion to occur. Later on emission control system use of the electronic distributor allowed for much leaner mixtures with wide plug gaps assisting with more complete combustion in the leaner conditions of the system. Mopar was the first to installed electronic distributors on road cars I think back in 1971 as they started the lean burn era. Cosworth was the first to use it on an F1 engine in 1967 on the DFX engine. Anyway electronic ignition works great for both performance and emission applications.
Dave

The 610 dual pts system was pretty awesome
1set of points for 1st & 2nd gear another for 3rd &4th gears , and retarded timing or you could say it let you advance lower gears more it ran thru shift fork switches
I worked on one in late seventies
After another Datsun tech kinda have up getting it to run well , I was given it , but it still missed out on 3&4
a VW tech ( they shared our shop)
Then took it over ,working on it for 1.5 hours
He pulled up to my door , I asked if it ran better ....he says get in ....I got a white knuckle ride it pulled very good in 3 & 4 , I think it had the switches 180 off it had 15 hps over the stock 610
This on a L 18 or L20
Back in those days there were tune shops with a sun distributor machine that got lots of work , my bfs neighbor back then owned such a shop he worked on Don Garlett's mags and got his to Chevelle smooth to 7k

My '73 620 PU came with a dual point. I switched it for the SSS single point version that had a "quicker advance curve" per the catalog. I ran a MSD 6A back then, never a problem. For the Roadster I loved my Jacobs Pro-Street and Ultra Coil with the EI dizzy before going crank-fired.