Timing on a J13

[Rusty Dawg]

Howdy,

 

Anyone know what the timing should set at on a J13?  I've read 6 degrees at 600rpm and 8 degrees at 600 rpm.  Which is it?🤪 

 

Since repairing the head and adjusting my valves to .015 inch, I've noticed a much quieter engine and a bit more H.P., but there is some pinging at higher rpm's.

 

I've read on this forum that it would just be best to drive the truck until it pings a bit and retard a bit.

 

Warm regards,

Roman

[datzenmike]

 

 

I get 8 BTDC but if it pings turn it down just enough to make it stop. You might try a different brand of gas.

 

 

Excessive pinging should be avoided. It can be caused by incorrect spark plugs and more important, the wrong heat range. I don't know the number but best to use NGK. Pull them and inspect. Dry sooty indicates running rich or driven short trips where the plugs don't have time to self clean them selves. 

 

Engine running too hot can also cause it to ping.

[Rusty Dawg]

Thanks datznemike.  I didn't have any ping until I correctly adjusted the valves.  That is the only thing that I have done to that engine in the past 8 months, so I believe it has something to do on why it developed after the fact.  The plugs are NGK, but I will check them to see how they look.  The ping is not excessive at all, but I notice it a little at higher rpm's after the adjustment.

Edited December 6, 2021 by Rusty Dawg

[datzenmike]

Well you could add some more timing. If the pinging increases then it's the timing. Then turn it back down. Setting valve lash shouldn't affect or cause pinging. Unless they were loose and made so much noise you couldn't hear the pinging before.

[Rusty Dawg]

You know what, I wondered the same thing about it being so loud before that maybe I didn't hear it.  Now I just hope I don't bust the bolt in the block that holds the distributor in place since it's super rusty😲  A warm engine and PB Blaster is my friend.

[Rusty Dawg]

Wondering, how shall I proceed if I cannot determine what RPM my idling engine is running at?  I have a timing gun, but no way to measure RPM's.

[datzenmike]

 

 

The idle isn't that critical as long as low enough that the mechanical advance is not interfering. You could check and set the advance with coil wire off and turning the engine with the starter.

 

 

[Rusty Dawg]

1 minute ago, datzenmike said:

 

 

The idle isn't that critical as long as low enough that the mechanical advance is not interfering. You could check and set the advance with coil wire off and turning the engine with the starter.

 

 

I never knew you could do that.  Thanks.

[datzenmike]

Well I don't see why you couldn't.

[Stoffregen Motorsports]

Maybe the distributor is worn out. Worn parts inside the distributor can cause erratic timing.

 

Also, if the spring tension on the weights is too great, high RPMs will pull in more timing and cause it to ping.

 

I like the timing to come in below about 300 RPMs and have it mechanically limited so it can never go higher than say 32 degrees. On an L distributor, this means removing one spring and shortening the slots in the distributor cam. If the Datsun distributor is anything like the BMC 25D distributor, it's even easier to adjust the curve. Jeff Schlemmer (distributorguy here on Ratsun) does this for a living, so you might reach out to him. He can rebuild and recurve your distributor for less than the cost of a new aftermarket distributor.

[Rusty Dawg]

Thanks for the contact.  I don't believe I am to the point of needing a rebuild since it's not that bad and only at higher RPM's does it seem to ping.  I am sure it probably could use a rebuild regardless though.

[Stoffregen Motorsports]

His business is called Advanced Distributors. http://advanceddistributors.com/wordpress1/

 

I guess my point is that if it is pinging, it could be a sign the distributor is wearing or incorrectly assembled.

[Rusty Dawg]

On 12/5/2021 at 9:22 PM, datzenmike said:

 

 

I get 8 BTDC but if it pings turn it down just enough to make it stop. You might try a different brand of gas.

 

 

Excessive pinging should be avoided. It can be caused by incorrect spark plugs and more important, the wrong heat range. I don't know the number but best to use NGK. Pull them and inspect. Dry sooty indicates running rich or driven short trips where the plugs don't have time to self clean them selves. 

 

Engine running too hot can also cause it to ping.

Well crap, I must've got confused with another truck since I actually have Autolite 405's in my Datsun.

[Rusty Dawg]

3 hours ago, Stoffregen Motorsports said:

His business is called Advanced Distributors. http://advanceddistributors.com/wordpress1/

 

I guess my point is that if it is pinging, it could be a sign the distributor is wearing or incorrectly assembled.

Thanks Matt, I will keep this info handy just in case.

[Rusty Dawg]

On 12/5/2021 at 9:22 PM, datzenmike said:

 

 

I get 8 BTDC but if it pings turn it down just enough to make it stop. You might try a different brand of gas.

 

 

Excessive pinging should be avoided. It can be caused by incorrect spark plugs and more important, the wrong heat range. I don't know the number but best to use NGK. Pull them and inspect. Dry sooty indicates running rich or driven short trips where the plugs don't have time to self clean them selves. 

 

Engine running too hot can also cause it to ping.

Well hell, which is 8 degrees BTDC?🤪

 

 

Edited December 19, 2021 by Rusty Dawg

[wayno]

 The joys of classic Datsun ownership. 🤣

Edited December 19, 2021 by wayno

[Stoffregen Motorsports]

The first three notches are likely 5 degree increments.

 

At least you can see them from the top. The timing pointer on a Sprite is directly underneath the crank pulley, so you need to check the timing while laying on your back.

Edited December 19, 2021 by Stoffregen Motorsports

[Rusty Dawg]

So what do you think the very first notch that sits farther apart than the other 3 represents?

[Rusty Dawg]

Don't plan to adjust timing until I can figure out what the notches represent, but I did put my timing light on it and it's reading below the 3 notches that seem to be spaced evenly.  It is basically lighting up right where there could be a 4th notch.  Not sure if this makes sense.

[datzenmike]

 

 

Rotation is clockwise so the pulley is moving from top towards bottom. So the bottom most notches are advanced and the top one by itself is probably TDC or 0.

 

Points gap is crucial as wear/erosion widens the gap and moves the timing towards retarded. Make sure the points are clean freshly filed or replaced before setting the timing. Gap also need to be set accurate too.

 

I would advance it (and leave the bolt slightly loose so you can quickly adjust on the road) and take for a drive. If it pings under heavy load, retard in small stages and keep going till it just stops.

 

Idle will change. Idle and weak cylinder filling take longer to burn so it craves advance. So once you get where is doesn't ping youi may have to turn the idle speed down... or up. Depends where it is now.

[Rusty Dawg]

16 hours ago, datzenmike said:

 

 

Rotation is clockwise so the pulley is moving from top towards bottom. So the bottom most notches are advanced and the top one by itself is probably TDC or 0.

 

Points gap is crucial as wear/erosion widens the gap and moves the timing towards retarded. Make sure the points are clean freshly filed or replaced before setting the timing. Gap also need to be set accurate too.

 

I would advance it (and leave the bolt slightly loose so you can quickly adjust on the road) and take for a drive. If it pings under heavy load, retard in small stages and keep going till it just stops.

 

Idle will change. Idle and weak cylinder filling take longer to burn so it craves advance. So once you get where is doesn't ping youi may have to turn the idle speed down... or up. Depends where it is now.

That was my guess that the very top notch was TDC, but wasn't 100%.  So basically I should clean or replace my points, gap, scrap the timing light and just use my ears.  Thanks for the insight datzenmike, it's always appreciated.