Retrofitting points, need assistance

[Chris#51EPGraham]

When and if all else fails:

 

Untape and examine the primary ignition section of the wiring harness.

Check all circuits related to primary ignition circuit, ign switch, alternator,

voltage regulator and distributor/coil/ignition module with an ohmmeter.

 

Also check associated black ground wires.

 

Ohmmeter readings should be way down in the neighborhood of 0.0 to 0.3.

They'll often be much higher than that on a 41 year old wiring harness. You'll

probably find a scorched looking primary ignition wire (white or white/red,

big 12 guage) and a many corroded crimp connections.

 

Repair what you find with new sections of wire and new crimp connectors

combined with soldering the connections. Use heat shrink insulation at the

connections. Keep re-testing your repairs until you get 0.0 to 0.3 ohms.

 

This kind of age induced wiring problem in the primary ignition circuit is

semi-well known in the world of old road racing and autocross cars. It's not

at all limited to Datsuns, but can afflict anything old enough to have a crude

wiring harness without sophisticated weatherproofing.

 

On race cars, it's aggravated by stiff spring rates and vibration. It usually

sounds like an irregular fuel system misfire since it may be triggered by bumps

in the road or engine vibration at certain RPMs. I worked through this problem

on my autocross 510 with a Pertronix ignition - it was not the ignition at all. It

took forever, but when I was done the misfire was gone.

[KFunk740]

Sorry, been busy and assumed this got buried.

 

Actually, I think hogboy is right. I think it's something with the mixture. How did I figure that out? Well one ridiculously easy fix: When the choke is pulled slightly, the truck cruises along just fine with no stumbling.

I tried richening up the mixture screw, and it still stumbles unless the choke is slightly pulled out. I had all the jets out and thoroughly cleaned them, but there must be some other problem. I've gotta dig deeper for vacuum leaks, or see if the idle jet is the wrong size. I might just get a rebuild kit for carb and replace most parts. Perhaps it just sat too long without enough driving, and got some gunk somewhere that I don't know about...

 

Oh, and I'm finally getting the terminal assembly that I need to retrofit the points tomorrow from the dealer. datzenmike helped me out with that part number, and I ordered it for 4 bucks. I still might try it out for fun, and maybe just leave them in my toolbox for emergency use, as planned.

 

Workin' 2 jobs kinda sucks for my tinkering time. But she's still a truckin every day. 3400 miles since June.

[H5WAGON]

What is the condition of the distributor......like under the points plate.?

 

The springs on the dist. mechanical advance could be week...broken....or weights not moving (rusted)

 

This happened on my friends car, it was like no wonder this things is not running right!..:unsure:

 

Also vac advance could be leaking under load....? Can you post pics....to see what you have going on?