Datsun Roadster Forum-311s.org

Hey guys, I could really use some input on this from others who know more than I do.

The last time the car was "normal", I was driving it normal and all of a sudden the car slowed down and the gas peddle force me to drive very slow on a level road, no hills thank god. The car got towed to my home and there it sits.

I tried to fire up the car a month or so ago, and it wouldn't turn over. I ordered and swapped out:

1. Points
2. Condenser
3. Cap
4. Spark Plugs
5. Spark Plug Wires
6. Car Battery
7. Rotor

With all that swapped out, the car was able to fire up, but it was only firing on 2 cylinders. It sounded very rough, and the motor was shaking like crazy.

I want to lean towards a blown head gasket, but I have yet to perform a compression test. I need to purchase a kit.

The car has a leaky rear main and the exhaust header is busted, so I had planned on pulling the motor and taking care of that in one swoop.

Besides the compression results, any thoughts on what I have in front of me?

Thank you

I would verify spark to all cylinders, then start it and pull each plug wire 1 at a time and listen for RPM drop, if you get 2 cylinders next to each other that are affected, cylinders 1,2 or 3,4 right next to each other, then maybe look into the carb that delivers to those 2 cylinders. Just a thought, compression test will of course tell you if you have dead cylinders.

R16 or U20?

If U20, rdmove the cam cover and check cam follower (some may say rocker arms) gap settings. If too sloppy due to loose adjustment locknut, it will not fire on that cylinder. Ask me how I know....

I have no experience with R16.

doesn't sound like a head gasket- would have to be really bad-they usually just leak here or there..If SU car, sounds like one SU choke (nozzle) is stuck or one carb is out of gas if literally running on 2 cylinders. If running on 3 cylinders could be a failed(burnt etc.) valve so your compression check will reveal this.

Triple check the plug wires for the proper firing order

Sounds more fuel than spark. As suggested, confirm spark to all cylinders. If good, then check for fuel especially if it's 1 and 2 or 3 and 4 that are dead, as indicated above. Purchase some starting fluid and spray that into the dead carb and see if it smooths out... if so, no fuel, somethings plugged or not working right.

Agreed on firing order for sure... 1 3 4 2 counter clockwise as I recall but I no longer run a dizzy so I don't think about it much.

He says it was driving normal then suddenly started this operation - firing order would not suddenly change while driving, although he could have messed it up when changing dist parts.

My guess is this wasn't ignition from the start- sounds more like a carb if it was literally running on 2 cylinders.

You said that it would not turn over. What does "turn over" mean to you firing and running? or cranking with no firing? or car is on its roof?

Perform a compression test before going any further. If the compression on all cylinders are normal and you have replaced the ignition system, the only thing left is fuel.

Once bought a SRL ($400) in the 80s from a widow whose husband had "rebuilt" the motor. Drove normally for a few hundred miles, then the cam snapped in two whilst driving, and it "sounded really rough, and the motor was shaking like crazy" as described above, b/c it was running on only the front two cylinders. Not that uncommon on a U20 if the cam isn't checked for ease of spin (head torqued, rockers removed) after a rebuild.

Hope this is not the case here, and if not, perhaps may still be useful information for new owners of 2000s.

Jon