Datsun Roadster Forum-311s.org

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If stock ign coil an easy/quick way to check is with a foot long straight blade screwdriver thin one hold it 1/4 3/8 parallel away from the coil with it energized ,
it should have a lite magnetic pull , also on the alt rotor / pulley
Take the pos wire off the coil ,will it pull current to lite a 1157 bulb ,elect.mtr ? Did you ever pull the plugs and crank it over ,see if it's throwing gas

Here are two videos I took yesterday. I have been going thru everything again to be sure I have proper timing, spark and gas. All are there. Has to be carboration - right? I have several carbs that I have reworked and cleaned, but have not rebuilt with kits. I have used the best ones I have re: free action of pistons (clunking) good looking needles etc, but admittedly not rebuilt units. I have worked on SUs over the years and can usually get clean carbs working reasonably well, so I am a little frustrated. If the videos upload you can hear what I have. I can get it to fire and stutter for a few seconds, but cannot get an idle. You carb guys can tell me if I need to drop the money and get a set from z-therapy. I don't want to do that and then have the same issue which is not carburetor related though, so what is your impression of these vids?

The first vid is unchoked, the second is with chokes engaged - not a lot of difference. No throttle response, so something is bad wrong.

It appears that the videos I dragged and dropped here only posted as pictures. Not sure what I did wrong or how I can get them to post correctly. Techies??

If your carbs are as nice (clean, tidy, and Premo-sorted) as your engine bay -----they are good. Did you follow Joe's coil guidance? If you followed Greg's (and Kai) guidance (brilliant tutorial BTW) on timing that should all be good too. I had a bad coil; cheaper than new carbs. And, I believe (experts correct me here) the EL dissy requires a different coil than your stock R16, (maybe you changed that already). Mine still sparked (I didn't OM test, like Joe described), but it wasn't correct and $30 made the difference.

Best way (maybe only way) to load a video is to save to Utube and post the link/URL to the video in the text section of the post

Man, I'm sorry you continue to struggle... been there plenty (last summer the car was down for a spark issue for a month, but that's my own mucking around with computers etc).
Here's the thing with your car... a carburetor is a crude device. The engine should fire and run even if they are not perfectly tuned (even crudely). Their basic job is to allow air and fuel in. With the engine cranking and the throttle plate slightly open it HAS TO suck in air (it has no choice), so not enough or way too much fuel would be in question. You have confirmed that it gets fuel (plugs are wet). You have tried alternative methods of providing fuel (starter fluid) and it STILL has not fired (BTW, you can run an engine on that stuff with just a spray... not a great thing to do but it should run... it's fuel and the engine doesn't care).

This all leads me back to SPARK. If that's wrong (not occurring, not occurring at the right time, not occurring in the right order, excessively weak however it doesn't take much to explode things!) THEN it won't run, or will only chug (ran my first motor, solex version 80 miles with two plug wires crossed on the dizzy).

Post a pic of your dizzy with the cap on and the plug wires hooked up just to make sure we can confirm firing order. Additionally, with the cap off, hand crank the engine while watching the direction the rotor is moving, and when it gets to #1 confirm the mark on the crank pully is near your pointer, then continue on hand cranking while watching the rotor to confirm the next plug wire will be the one that fires #3 (1 3 4 2). Get a timing light (Harbor Freight, cheap dialback) hook everything back up on the dizzy etc and confirm spark and timing on the crank while the engine is cranking (keep in mind that 1 and 4 will both flash in the correct manner but #4 would be 180 degrees off).

With all of that happening i.e. IF we have fuel (can be carefully supplied by a short 1 second hit of starter fluid... don't be scared/worried, just realize you're supplying an explosive vapor and act accordingly, and you're not looking to run the engine for more than 5 seconds or so), spark and compression it MUST fire. Your job is to figure out what's not present. If it chugs or runs like crap, then you know it has all that is REQUIRED but not in the correct amount or time. Ignition timing we can adjust by turning the dizzy and observing the result/flash (engine should run/idle with anything from 8-20 degrees, with higher numbers likely increasing rpms, lower numbers making it easier for it to start from my understanding from my own system but the engine may also idle slower so adjust the throttle plates accordingly). Fuel is metered by the needle and seat/nozzle, with more fuel being sucked in by the engine the higher the vacuum created by the piston pulling in air determines (not a lot of fuel being pulled when cranking). Turning the dial on the bottom of the SU or operating the choke pulls the nozzle downwards and exposes more of the graduated needle and opens the throttle plates slightly which allows the engine to pull in more fuel even though the carb piston isn't allowing in a bunch more air (richening or leaning the fuel mix). After that, adjusting the carb is based on balancing airflow carb to carb and setting the throttle plates so they control rpms at idle, and adjusting the nozzles or changing out the tapered needle to change air/fuel ratios at desired rpms.

I understand that you probably already know all this, but sometimes it helps to break it back down so you can visualize what's happening so you can ask yourself and the engine the "right" questions.

Keep hammering, we'll get it...


P.S. You were questioning spark... agree with others to try swapping coils and reviewing all the EI wiring, and confirm there is spark coming out the plug wire(s) via a spark indicator light (Harbor Freight again) or an insulated screw driver in the wire held a 1/4" away from the valve cover while cranking to see the spark.

If the engine will run for even 5 seconds semi-normally on starter fluid but then dies out unless you keep hitting it with shots of fluid, you know it's a fuel issue.

Pull the coil wire out of the distr.
Then with a leather glove or sp wire plyers crank to see it arc on the valve cover , ( unless you have or suspect any heart problems ),if so then plug it back in and try it with SP wires . Which tells you the spark is there , pull all plugs crank over and watch the holes ,what comes out how much fuel mist .
It not advisable to start a new /rebuilt engine on all cyls do it with 1 middle plug /cyl which if it is firing will only spin the flywheel a bit faster than the starter ,this gets oil pressure going thru out the system while it's turning 100 rpm or 1.5 X per second, instead of 50 Xs per sec like at 3k , that will save all the work and $$$ if something is arye & you need a competent helper here I'd do the compression test only to get the 1st pump readings again , I've had a car or 2 with this situation , the exhaust was plugged up , cc but not likely here
Yeah that sounds either very retarded ign timing or cam timing ,or very lean
If you give a shot of carb spray does it rev up quick. No vac Leaks ? bet it's a tooth off unless the exhaust is almost plugged

Thank you all for hanging with me. I will go out later and try all the new suggestions and get new pixc. In the meantime watch this youtube vid I took yestarday. After messing some more, New spark plugs, changed out the coil to a MSD I had on another car etc. it is running but badly. a steady sputter/stagger you see here. I'll report back and enjoy the vid. I don't!

https://youtu.be/UE-KNibxlpM

Looks like a spark issue to me. Start it, pull one spark plug wire at a time... I bet that you will pull one (maybe two) that don't make any difference. Pls post pic of cap... hard to tell. Bad rotor? Cap issue? Has compression been checked in all 4? Valves are closing fully? What do the plugs look like now?

You have checked the float levels I presume.

Fire at coil wire and spark at each plug wire. Here are the pictures. Reversed wires (4 to 1 and 3 to 2 on the dizzy) just to be sure I am not off 180. It backfires thru the carb and does not fire as one would expect - just trying to eliminate anything.....

Hmmm, everything I can see looks right... we may need another set if eyes/hands in it just to get a different perspective. Thinking...

Well... if you're getting spark confirmed at all 4, then I guess we move on to fuel. Let's check linkage... are both throttle plates appearing to be the same/very close to being slightly open the same amount and operate the same? Will it run better or smoothly with a blast of starter fluid? It's possible one carb is not getting the same amount of fuel... but it doesn't snap or bark out the carb when you try to increase rpms sharply (lean condition)... but you tried different carbs right? Are we able to confirm fuel flow to both carbs... possible plug in a line or banjo filter? BTW, pushing up the carb piston at idle in essence turns off that carb as the thottle plate is what controls airflow. Take a close look at your linkage and be sure you understand how it all works... I believe there should be a screw for idle, a balance screw and two separate screws that adjust each throttle plate individually. Set the individual throttle screws so they are opening the plates the same, set the balance screw that links the two together so it operates them as one (usually needs a flow meter to get perfect), then set the idle screw for desired rpms at idle. As I'm sure you know, the dial on the bottom of the SU adjusts air/fuel... try screwing those in all the way up then turning them down the same, like 2.5 turns or so... you can also remove the domes and visually look at the position and condition of the nozzle... no oval holes allowed.

While it's running you can also turn the dizzy a little bit and see what effect this has as you advance and retard the timing.

My only other thought is that there's a cam timing issue since it's been apart but I'm not ready to go there yet... compression isn't bad, motor is newish and the rings are not likely seated yet, but 140s seems a bit low to me... thoughts anyone?