Datsun Roadster Forum-311s.org

Hi all, new to the forum, just posted my intro, now I have a tech question:

It won’t start. (Darn.)

1970 1600, no service records, carbs were off when we got it. Engine was “lightly stuck” when we got it - freed it by pulling the head, pulling the starter, adding Kroil to cylinders (which aren’t scored and have little carbon ring at the top), and a pry bar on the flywheel. Took about 5 minutes - it’s been suggested that we don’t need to pull the head, oh well, live & learn.

New thermostat & housing, belt, hoses, gas tank, cap, and lots of other good stuff (non-engine stuff, too - we visited Mike in Lake County!)

New cap, rotor, points, cables, plugs new & correct gap; tested coil with multimeter, is good

All spark plugs are sparking; valves are opening & closing; compression is 70-90 on all 4 cyls, which I know is low, hoping that the rings free up if & when it starts. We’re getting fuel in both float bowls; and I replaced the little connector hoses from the float bowl to the jet valve(?) because they were hard, cracked & leaking.

When we crank it, it “puffs” out the carburetors (we think it’s backfiring?) once or twice out of every 10 revs. If we retard the distributor, it does it more. If we advance it, it just cranks. Thank goodness there’s no valve-piston interference noise - I’d REALLY like to hope the timing set isn’t damaged, but I haven’t had the timing cover off.

We’ve tried rotating the plug wires to each of the other 3 positions, just in case. At 90 deg farther (plug wire 1 goes to position for 3 on the cap), it sounds like it’s trying to start - faster revs. At 180 deg farther (wire 1 to cap 4, etc), we got several loud after-ignitions out of the tailpipe (very exciting!) At 270 deg (wire 1 to cap 2), it didn’t do anything interesting at all - no backfiring, no trying, no after-ignition. (We also tried retarding and advancing the timing in each of these positions, with generally no effect.)

So -
- Does it sound like a carb problem? The float bowls are missing their air inlet screws, the threaded holes are just open - would that matter? Should I reset the idle knob in the bottom of the jet? I also don’t have a choke cable, and I can’t find a picture with one - is that where the throttle return springs are supposed to attach? Does it just need to be choked to start?

- Or does it sound like timing still? Could the distributor be incorrectly aligned in its hole in the block? I’ve heard people have problems getting their distributor back in - I didn’t take it out, but maybe the previous person did?

I’m trying to learn how to fix this myself, but I can’t tell if I’m headed the right direction. Like, at all.

I’ll really appreciate any suggestions anyone has!

Thanks,
Eric

(Walter & Buddy are our dogs)

I would suspect that the plug wires are crossed

You don’t want any gas sloshing out of the fuel bowls after starting so I would fix that first.
Carbs do have to be set up correctly and be clean, so might want to check Tech Wiki to see pics of parts and follow tune up process. Best to have plastic floats as the brass ones can have pinhole leaks and sink.
You can set the valves cold , see Tech Wiki, just so you know one isn’t stuck or too tight.
Re distributor set up: Does the rotor point to#1 plug at TDC? Also check the pigtail wire in the distributor, a sneaky way to fail starting...
Just a few ideas for you

Linda

Have you checked the centrifugal advance deep down in the distributor?

Have you double-checked your camshaft timing?

You do not have normal compression ...that's a problem... oil added test done? What was the 1st pump pressure
Possible slow valves , a leak down test worth it , blowby test
the cam timing ?
Getting good oiling up top?
Did the rings seem free with heads off?
Do not use starting spray ...either on it possibility someone did
Yeah probably multi problems but longblock needs fixing before chasing other symptoms
If you get it running and it's out of time cam wise it will / could destroy it

I would start from scratch setting your timing. Plugs firing order is 1-3-4-2 COUNTER clockwise. Are you familiar with Static timing, using a 12V Test light?
A choke will make a big difference in getting it started cold, you can manually set them - use a string or something to pull the levers up to see if that is what you need.

I am very troubled that you were so unsure of the firing order that you tried every #1 position.
If the firing order and cam timing have been double checked and its static timed, then try bypassing the ballast resister.
I would make up a short clip with alligator clips at each end and clip across the resister when cranking. You need to remove one side when it starts. You can not leave the bypass on when not cranking because it will overheat the coil.

To check the cam timing and #1 position of the distributor:
Remove all the plugs and valve cover. Rotate the engine by hand until the exhaust valve of #1, one closest to the front of the engine, is just closing and the intake valve is just starting to open. Confirm that the crank timing mark it very close to TDC, marks lined up. The distributor rotor should be pointing to #4

HowToInstallADizzy

Thanks for all of the help! I’ll post here as soon as I complete these tasks. (It’s also the last week of school before Christmas break, so I may not get to it immediately.)

Whew, finally mostly done with fall semester! Thank you for all of the comments - here goes:
1. Plug wires are not crossed
2. Floats are brass, no leaks, they float - I’ll get those little valves screws that are missing from the top of each float bowl
3. Valves set cold according to wiki
4. The rotor is about 45 degrees before #1 distributor contact when engine is at TDC - pointed toward ~between cylinder 2&3 - I can wiggle the distributor shaft cw a little, but not ccw
5. We get spark every time, pigtail seems good
6. Haven’t checked centrifugal advance - what do I check for?
7. Did static timing check, valves open & close correctly according to all your instructions
8. “Oil added” compression test gave those readings
9. Valve oiling seems correct during cranking
10. I don’t know how to check rings with head off?
11. Won’t use ether starting spray, don’t know if anyone else did
12. I will try using string to lift the chokes
Phil - I haven’t tried bypassing the resistor yet, I’ll wait till I hear anyone’s thoughts about the rotor position.

After all this, it seems like the rotor isn’t pointing to #1
on the distributor at the right time - I think that explains why it feels like it’s igniting the mixture as it’s leaving the cylinder.

Does the distributor need to come out & go back in correctly? It hasn’t been removed since we got it, but who knows what the person before me did.

Thanks for all your help!

It does sound like you need to move the distributor a tooth or two clockwise based on your description. Look at section K starting on page 10 here: http://www.311s.org/PDFs/InstallRoadsterEIDizzyrev6.pdf

If the rings are siezed on the pistons the pistons are immoveable side to side ....move when up top. You can place a thin feeler guage on the cylinder ( it protects the cyl ) and take a flat screw driver tip between both to twist it litely to see the piston move
Centrifugal advance try gently turning distributor rotor forward if it's siezed it will not move ...try chem blaster on the pivot points of the weights ...also onthe valve stems thru the springs
Cylinders walls were bright iron no rust ?
I'd do a compression test again ...write down the 1st pump of the test how many psi s how fast does it turn over trying to starting
A compression test can tell if cam timing is off and that even low pressure hints to it

As noted, sounds like a distributor/ignition timing issue. Set the engine to the correct timing mark on the crank and #1 cylinder is on its compression stroke (16, each mark is 0, then 5, then 10, then 15, ends with 20 for an early non-smog engine; or 0 for smog ALL ASSUMING IT HAS THE CORRECT DISTRIBUTOR/CURVE FOR THAT MOTOR IN IT), then rotate the distributor with the key on and the cap off until the points open/spark, then snug the set bolt down so the dizzy doesn't move easily. The engine should now fire the plug at or near16 degrees before top dead center (or 0 for smog... all advance is built into the dizzy). The engine should be close to its initial timing and can be checked/adjusted to final with a timing light. Now, if it takes more rotation of the distributor to get the points to open than what is allowed by the set bolt, it means your distributor drive gear is one or more teeth off as it meshes into the tach and oil pump gears. That takes some practice and trial and error to get that gear clocked correctly, but we can walk you through that if needed.

Thanks for the suggestions!
We’ll move the distributor back one tooth, then a second if needed.
The centrifugal advance weights are moving fine - thanks for that explanation!
Cylinder walls: 124 were bright, 3 had a little rust, came off with light extra-fine steel wool, then blew & wiped it out (not our first seized engine, unfortunately!)
Will let you know the results over once timing is correct, then will redo comp test
Thanks!

It’s nice to know if you have a smog distributor or a non smog. Has all the smog stuff been removed? Then you probably have the early or at least modified to be, early distributor, for 16 deg before TDC timing.
To review, for the newbies, took me some retries to get this at first, TDC is when the #1 cylinder is moving up and compressing the air, so that you feel some air pressure on your finger held over the spark plug hole, as it rises to the top of the stroke. You can see/ feel the top of the piston thru the spark plug hole, and valves should be as described earlier. That will wind up being 0 , compression stroke, on the crank pulley as you rotate the engine. Your distributor rotor should now be pointing to a distributor terminal, and towards the #4 cylinder , or pointing to a terminal that corresponds to the small lobe backward” pic on the “How to install a dizzy” link. Either one. If it is off , the dizzy is a tooth or 2 off as mentioned.
Just another way to explain it , which I find easier to remember, so that you can be sure before you mess with moving the dizzy, which I always had trouble doing at first.
Good luck!

Linda