Datsun Roadster Forum-311s.org

When I set the timing on my 2000 to 16 degrees BTDC (with a timing light) I loosened the bolt that faces up and is on a plate with lots of lines on it for fine adjustment. After a very disappointing test drive, I realized that there are two bolts facing downward that also allow rotation of the distributor when loosened. After some research I'm still confused but I think the upper bolt sets the distributor timing and the lower bolts should be used to set the ignition timing?

I don't know how I set the upper adjustment when I put the re-curve kit in about 30 years ago and I'm not finding any information. Can someone please give me a lesson on this and/or point me to a link that does?

Thanks

Did you have the distributor out at some point? At any rate, you may want to have a read of this thread:

viewtopic.php?p=324965#p324965

While the thread Bwk2000 guided you to is a very good read, the answer to your question is that both adjustments do the same thing. Adjust the part of the distributor with out the lines first (with the little arrow pointing to the middle position). Then use the adjustment that utilizes the lines for any additional adjustments. This lets you make small adjustments after your initial timing without the use of a timing light.

In really, really simple terms, and ignoring ANY deviation from original, here is the concept:
Static time the car.
Set the "pointer" on the base plate at the "0" marking on the tower it sits on and tighten the mounting plate at that point.
Loosen the second bolt on the bottom of the distributor, and using a timing light, set the timing to 20 before TDC.
Secure the bottom bolt.
Now, in theory, you can use the accessible mounting bolt and the pointer to advance or retard the timing from the initial setting (20 degrees BTDC)
by the degrees displayed.

Thanks for the input.
So it sounds like if the timing light shows 16 degrees BTDC it doesn't matter which of the two adjustments on the distributor were used. That means I've got something else going on that's making my car run really bad. The only work I did was to replace a bad head gasket and I got my cam reground to take care of some pitting. I kept it stock (A grind) and I thought that I could just re-install it and I'd be good to go (cold valve clearance was set at 0.006 intake and 0.010 exhaust). Now the car feels like it lost about 50 horsepower. It just doesn't build up speed as fast as it used to. If I floor it at low RPM it stumbles a bit and then slowly accelerates.
I guess I'll see if adjusting the carbs will get it back to where it was. I'm open to any additional input anyone has.
Thanks

I would try 20 BTDC and see how that effects running performance.

I'll try that tomorrow, thanks.
How advanced can you go before you need to start worrying about engine damage?

Until it knocks.

Also, set timing at idle with vacuum advance vacuum line disconnected, then connect the line and confirm the advance is working using your timing light as you increase RPMs

At this point I would probably do a compression test (It can help determine if your cam timing is off).

The first thing I would do is to remove the valve cover and static time to TDC. Now check to see if the small hole on the back of the cam gear is lined up with the little arrow on the front cam cap. If not very close than you have installed your timing components wrong.

What Mike just said and posted great pics of... a few degrees in ignition timing should not cause your engine to lose what feels like 50hp. Given that you removed the cam, I suspect you may have gotten it (MECHANICAL TIMING, not ignition timing) a tooth off. Absolutely DO as Mike says... set crank to TDC (far left mark on pully with you facing the engine from the front) for #1 and observe your cam marks. A full tooth off will be obvious (post pics if you're unsure, but Mike shows it clearly; hole in cam gear, arrow on cam bearing cap). This can be dangerous territory for a U20, as it can lead to piston and valve contact so the cam/crank timing must be correct. Just curious: When you removed the cam did you set the engine to TDC on the crank and mark your cam gear to chain position (I use a sharpie). I've done this many times but still got it wrong recently after I had some crank movement... doesn't take much. Once we are completely sure the top is timed with the bottom we can be sure we're safe. If it still runs bad, then we can explore what the IGNITION timing is doing. In this same condition (engine at TDC, cam and crank timing confirmed), rotate the engine backwards (to the left) until the pointer is slightly ahead of the 4th mark (0, 5, 10, 15, 20 marks on the crank) and that should be right about 17 degrees ignition timing. Then, rotate your distributor until the rotor is pointing at #1 on the distributor cap, then lock it down (engine was just "static" timed). Best to confirm with a timing light, or of course you can just check/adjust it while running with the light if it's already close and not have to static time it... your choice, but thought I'd mention it while you were right there.

Not sure if this is of any help but do you know if you have the smog or non smog distributor? They have different timing settings. I had to pull mine apart to figure which one I had.

Thanks to everyone for all the great input.

I've got it close to running like it did prior to my engine work now. I moved the timing to 20 and I'm going to try going further because that helped a lot. It's weird since it was set at 16 when it was running better. I also made the mixture richer. I didn't get a chance to drive it much but it felt a little weak at low RPM still.

I'm going to spend some time confirming the vacuum advance is working right. I got about the same amount of additional advance (around 10 degrees I think) when I sped the engine up with the vacuum tube clamped or not clamped. I'm thinking this was just the mechanical advance working. There is a mechanical advance in the distributor, right? I need to actually remove the tube and try again. If the clamp was leaking, I may have been seeing a combination of vacuum advance and mechanical advance?

Oh, and the cam was installed right (the small hole on the back of the cam gear is lined up with the little arrow on the front cam cap).

I'd appreciate any additional comments you all might have.

I'm glad that the cam was good, that can be a significant issue. However, something seems amiss still. I want to caution you about over advancing the timing. If the spark comes too soon in the stroke you are making the engine fight itself, and that's not good and will result in reduced power and potentially damage. Check out a YouTube video on ignition timing/curve and what that is designed to do and you will better understand what's happening. Confirm that your timing light is set correctly, especially if it's a dial back. Did you have to adjust your idle screws after you put it back together? If so, that suggests a change in timing from where it was.