Datsun Roadster Forum-311s.org

Just fired up my U20 this morning and ran it for 20 min @2Krpm. Seating new rings and noticed upon starting to drive it a bit that it seemed to ping. Shut off and checked timing to find that the light didn’t even line up with marks on pulley. Looked like timing was way advanced. The timing marks on pulley way down at about 8:00 position. Adjusting dist to retard seemed to get marks closer. After even a adjusting secondary lockdown bolt all way out to limit and primary hold down to limit it’s still ahead by about 1 inch. When I set this all up the jack/crank chains were never messed with still in time. Distributor drop in gear meshed at 11/25 position like manual. Cam gear was just a tad ahead of arrow mark on cam cap. All looked good and rotated engine many times, no binding valves to piston. Started right up. Question, Is there really only one position the drop in gear will ever line up with Jackshaft? Besides 180’out. Where do I even start troubleshooting? I tried pulling dist to reposition drop in gear to retard position but it only seems to mesh at 1 or 2 positon. Is the Jackshaft keyed only to mesh at certain spots? Suppose I could pull the limit screw/bolt from dist and keep rotating backwards. I noticed also that at TDC number 1 plug rotor position on dist seemed slightly ahead of corresponding spot on cap like it had already fired. Dreading pulling the timing cover again if it’s Jackshaft position. Please advise,

The oil pump drive dog, at the bottom of the distributor shaft is slightly offset and can go on two different ways, however if it dropped in at the right position and lined up, that is not likely your issue. The distributor doesn't really "care" what position it is pointing to when installed, just that you have it in the correct firing order for where it is installed. Also, are you checking timing at idle (under 800 RPM) or at 2000RPM? The timing should be advanced at 2K vs at 800.

The casting that the distributor sits on (the part that has the drive gear for the tach cable) can be pulled out and reindexed. I'm not sure why you would need to do that if you haven't changed the timing though. I'm only aware of this because I bought an Electronic Dizzy from East Coast and it was too far advanced-even after backing off all the way. Tom brought to my attention that I may have to mess with it. For the time being I just put the old Pertronix back in but at some point I will have to deal with it.

Yep, has nothing to do with the jack shaft position. Sounds like you installed the distributor drive gear a tooth off from where you had it before. As noted there is a slot and an extension on the gear to connect the distributor to the gear (the oblong slot in the shaft of the gear) and to the oil pump (extension or spade that goes into the oil pump shaft). So, you have to rotate the pump into a position such that, as the gear slides down AND rotates AS IT MESHES WITH THE GEAR, it turns such that the extension or spade slides into the pump slot. This can take several tries and slight adjustments. As you know, the desire is for the oblong slot to be in the 11:25 position when the engine is at TDC.

So, rotate the engine to 0 on the crank pointer (make sure you're on #1 and not #4 or you'll be 180 degrees out and it will fire plug #4 instead of #1. If needed, check your cam to confirm the next event will be that the exhaust valve will open if the engine were to continue rotating, clockwise as you face the engine). Then, adjust your oil pump slot position with a slotted screw driver to your best guess and then slide and rotate the gear in, and assuming it seats down check your slot position for 11:25 (if it doesn't seat down it could be that it's not fitting into the oil pump slot). If off from 11:25, pull the gear out, adjust everything accordingly and try again. You'll get it eventually. Your distributor has two adjustments; one is the main 10mm bolt/slotted plate, the other is an 8mm bolt on the underside that also allows for more adjustment if needed. These may have been changed in the past to accommodate for how the gear was positioned before, so your old marks may not line up. It's possible it was off a tooth before but the distributor was adjusted enough to work correctly.

Post again if you continue to struggle...

Re read your original post... do make sure you are on #1 at TDC (0) as described above, confirmed with the cam position. Your post kind of suggests you were/are 180 degrees off Or? With the timing marks showing up at 8 o'clock you are waaaay advanced. Also, the engine MUST be at TDC when you install the gear. If the engine is not at TDC you will still be able to rotate the oil pump slot and install the gear at 11:25, but it won't be aligning the distributor to the crank/piston/cam position so it won't be timing the spark correctly... like what you're seeing...

Notoptoy, makes a good point, I don’t think it was at idle that I saw the timing off. Certainly wasn’t at 2Krpm though. I will re check at good idle and report back. Hope I don’t have to pull the timing cover again.

No front cover removal needed... has nothing to do with the chains etc, has everything to do with being at TDC and installing the gear. You're welcome to call me... 253 230-3484.

Suggest you start with the basics. If the timing was 180 out, it would not have run politely for 20minutes.

Just turn the crank to exactly TDC. In that case the distributor rotor should be pointing DIRECTLY at the #1 cap terminal. NOT 20degrees before, not 20 degrees after. It's ok to rotate the distributor within the adjustment range to achieve that position.

Is that correct? (your original post seemed to indicate not)

Check compression too , head milled ?
If your using premium grade gas , just know that can be old gas you just bought causing the knock / pinging 3500 -4000 RPM is the power / torque area so keep it near that driving

The outer ring on the vibration damper can come loose and the timing marks may not reflect the true position of the crank.

I tend to agree with spyder.

You need to verify that the pulley on your crankshaft vibration damper has not slipped.

Remove the no. 1 sparkplug and position the piston at TDC. With the piston at TDC verify that the mark on the pulley is at 0 degrees.

If not, this indicates that the pulley has slipped with age. This will now be your new 0 degrees and mark the pulley.

The alternative is to replace the assembly.

Let’s not go chasing unicorns just yet. Yes, the balancers can slip, but that is fairly far down the list of likely problems. Since the engine was pinging badly, it sounds like the timing is actually way advanced.

Back to question#1, if you turn the crank to exactly TDC, is the distributor rotor pointed exactly to #1 wire terminal?



There are two slotted adjustments on the distributor, if you loosen both and rotate the distributor all the way counter clockwise (most retarded) what does the timing light show?


Also, suggest you disconnect the vacuum advance if one is connected. (For troubleshooting).

Hi JT, as noted earlier it seemed like the rotor was a tad ahead of the cap terminal as though it already fired #1 and on way toward #3. That is why I was trying to offset the drop in dist gear to more of a 12:30 position to retard the rotor. It seemed like I was 1 tooth off. But it only drops in at 11:25 no matter how I offset the oilpump slot to 12:30. This is with crank at TDC and Cam at arrow to cam cap. Will Dist drop in gear ever line up other than the 2 positions of 11:25 or 180’ out? I tried maxing out both adjustment bolts on Dizzy. When I keep retarding the Dizzy it does get closer to home position.

Yes, the dizzie will line up an a multitude of spots, you'll just have to turn the oil pump slot to match where you are relocating the gear. IF you move from 11:30 to say 11:00 or otherwise, you will then have to move the pump slot to align so you can drop the dizzie in. This is a time consuming and often frustrating procedure the first few times, but you'll figure it out!

Thanks Notoptoy, That’s encouraging to know and I was trying. It’s always been a bit fiddly dealing with the Dizzy. Will try again to retard rotor positon to about 12:30, maybe that’s all it needs.