Timing tape U20

[dbrick]

Just a thought...Does anyone here have the ability to make precision vinyl stickers? Reason I ask is it may be very nice to have a timing tape available for the Roadster. Basically it's a sticker that goes around the harmonic balancer and gives you degrees instead of notches and makes it foolproof to check and set timing. It needs to be laid out carefully to the right circumference and wrap around and overlap an inch or so and be high quality vinyl to stay stuck, but simple enough. Add marks for adjusting valves would be a plus. I would be in for a few.
IIRC, we are between the standard sizes below.

.

[Copterpilot]

What a great idea! I'd certainly be interested also.

[tjp]

I'd be in as well.

[CameronSF]

Any printer can likely print this up on appropriate vinyl to specs if you have the art. Do you have the actual art file for the image you posted or was that just an example? Otherwise you would need someone to produce the art file in a vector program like illustrator.

[ua3172]

I have the ability to create a vector file for production... if you send me the specifications and the image I can create the file as a pdf and illustrator vector file and send it back to you

s king

[dbrick]

I have the ability to create a vector file for production... if you send me the specifications and the image I can create the file as a pdf and illustrator vector file and send it back to you

s king

Really all you need to do is ACCURATELY measure the U20 balancer outside diameter and width, make a 360 degree scale to the right length, and leave a "tail" on it so you can start at the timing mark, wrap it around, have the TDC mark end up at the point you started and overlap an inch or 2 to lock it in place. Quality of the vinyl is a big factor.

Anyone have a balancer and a vernier caliper on the bench?

[originalowner]

Did anything ever come of this last year? I am making a new distributor cam for my U20 engine. The 1600 distributor robs power from the U20, or does not idle properly if set for max power. I need a timing tape to plot the new curve.

I can generate a vector file, and I can print it, but I do not know where to get a sheet of vinyl. BTW, the U20 harmonic balancer is 5.125" diameter (130 mm).

Joe

[dbrick]

1600 and 2000 basically have the same distributor in the same years. You have either an early, up to 67.5 or late/smog advance cam in the distributors, early is marked 7.5 and timing sets at 16 BTDC with 15 degrees of advance giving 31 deg total timing and the later smog distributor has a 17.5 cam, timing sets at 0, TDC and gives 35 degrees advance and total timing above 3500 rpm. An advance timing light should let you check. Do not exceed 35 degrees total timing.
You can read the marks by removing the point breaker plate. or look under it. 7.5 has radial slots [-- O --] and the 17.5 has angled slots [/ O /] both have the number is stamped on it. They also tend to get rusty and nasty with broken springs etc screwing up the advance.

The early 7.5 set at 16 BTDC will almost always make the car run best.

[originalowner]

Hi Dave,

I am the original owner of a 1969 SRL-311. I am trying to keep the car in original condition. It still has the air pump and the fan clutch. When I discovered that there was a broken spring in the smog distributor, I could not find a replacement, so I installed a "new" distributor. As I mentioned in the original post, it is not as powerful as the distributor I have driven for 40 years (when timed at 16°) or it does not idle properly (timed at 20°). What I believe happened is this distributor was designed for the high performance kit (camshaft, carbs, oil pan). There is no vacuum port on the Solex carb, so the distributor was set at 20°, and nobody cared whether a racing engine would idle properly (maybe it would with the Solex).

I suspect they did not want to design a separate distributor, so they "detuned" this one (timed at 16°). But when the smog requirements came along, they could not meet emissions at idle, so they had to redesign the distributor. It would meet smog at 0° intital timing, and they ran the advance up to 35° which gives the high performance to which I am accustomed. People who acquire the U20 engine today have no idea what the potential is, but I am not happy with the detuned version which you (and everybody else) recommend.

So I have designed a new distributor cam with 12.5° advance. Timed at 10° it will idle nicely, and the advance is correct for high speed.

Now. About the timing tape. Did anyone ever make one for this engine? There are some on the market that are close, but I would prefer to have one that is correct, so I can plot the new advance curve. I will read RPM on the tach and read the advance angle with the timing light. You are correct that I could invest in a good timing light instead.

Regards, Joe

[tjp]

I have a set of smog dizzy springs. NOS in the bag if someone needs them.

[Solex68]

Just a thought...Does anyone here have the ability to make precision vinyl stickers? Reason I ask is it may be very nice to have a timing tape available for the Roadster. Basically it's a sticker that goes around the harmonic balancer and gives you degrees instead of notches and makes it foolproof to check and set timing. It needs to be laid out carefully to the right circumference and wrap around and overlap an inch or so and be high quality vinyl to stay stuck, but simple enough. Add marks for adjusting valves would be a plus. I would be in for a few.
IIRC, we are between the standard sizes below.

.

I want one of these! I have been thinking about this as well. It would be easy to create one on paper but getting one to stay on is another story.

[Gregs672000]

Hi Dave,

I am the original owner of a 1969 SRL-311. I am trying to keep the car in original condition. It still has the air pump and the fan clutch. When I discovered that there was a broken spring in the smog distributor, I could not find a replacement, so I installed a "new" distributor. As I mentioned in the original post, it is not as powerful as the distributor I have driven for 40 years (when timed at 16°) or it does not idle properly (timed at 20°). What I believe happened is this distributor was designed for the high performance kit (camshaft, carbs, oil pan). There is no vacuum port on the Solex carb, so the distributor was set at 20°, and nobody cared whether a racing engine would idle properly (maybe it would with the Solex).

I suspect they did not want to design a separate distributor, so they "detuned" this one (timed at 16°). But when the smog requirements came along, they could not meet emissions at idle, so they had to redesign the distributor. It would meet smog at 0° intital timing, and they ran the advance up to 35° which gives the high performance to which I am accustomed. People who acquire the U20 engine today have no idea what the potential is, but I am not happy with the detuned version which you (and everybody else) recommend.

So I have designed a new distributor cam with 12.5° advance. Timed at 10° it will idle nicely, and the advance is correct for high speed.

Now. About the timing tape. Did anyone ever make one for this engine? There are some on the market that are close, but I would prefer to have one that is correct, so I can plot the new advance curve. I will read RPM on the tach and read the advance angle with the timing light. You are correct that I could invest in a good timing light instead.

Regards, Joe

Well... I'm not so sure about all that... As stated by others, they all eventually get to about 32-35 degrees total. The difference is the non-smog cars had an initial of 16 degrees with SU, 20 w/ solex, with the distributor then advancing to total. Vac advance was disconnected on the solex as it is PRIMARILY for fuel economy and throttle response, not needed for a "race" engine. The smog distributors as set at 0 and all the advance was built into the distributor cam, again to 32-35 total. I suspect that you are or we're over timing the engine running a smog dizzy at non-smog initial timing, so the engine was fighting itself big time. A distributor is not "detuned"; it's job is to time the ignition of the fuel so that the fuel has time to burn fully, and that is determined by how the engine burns fuel, combustion chamber design, fuel grade and ratio, RPM, load, etc. Your current new set up probably works fine, though it probably wouldn't have met emissions goals that Nissan had at the time.

Perhaps this is what you're saying above???

[originalowner]

Hi Greg,

I am giving you my experience. There is a big difference in performnce between 31° and 35°. When I timed the new (7.5°) distributor to 16° BTDC it took me a block to tell it was a pussycat. The same distributor with Solex carb is timed at 20°, which gives 35° max advance. My engine (with SUs) ran like a tiger when I tried 20°, but it would not idle. Keith Williams told me there was no port on the Solex carb for a vacuum advance. When I was at Solvang, I checked, and sure enough there is none. They did not just disconnect it.

The original smog distributor is 17.5°, so it gives max timing 35°, not 32°-35°. I saw the range on the charts, and that confused me for awhile, too. The range is only for manufacturing purposes. If they produce a cam that is only 16°, it does not have to be scrapped. The cams, once built, are accurate, and they can be held to very tight tolerances.

Yes, the EPA set very tough standards for this engine (BTW, I always changed the plugs and points first, and it always passed smog with a wide margin) Gasoline engines always run rich, they never "burn the fuel fully." If you set the carbs too lean, the engine will overheat. So they added the air pump to burn off excess fuel in the exhaust, but it would not meet the spec at idle until they reduced the advance to zero degrees. The engine runs very well at zero. (I have never set the smog distributor at 16° or 20°, I suspect it would backfire violently with 50° advance.)

I reviewed typical 1969 Jaguar distributor curves (they use SU carbs, too); they normally idle at 10° BTDC. That's where I set my custom 12.5° distributor cam, when I get it finished. But as you point out, it would not meet 1969 emissions requirements at 10°. (Probably the air pump does not run fast enough.)

My owner manual states the engine should be run on premium gasoline. Reducing the max timing to 31° would help with ping if you want to run regular. And yes, I call that detuning. ;~)

Regards, Joe

[originalowner]

I have a set of smog dizzy springs. NOS in the bag if someone needs them.

_________________
Hi tjp,

That would be cool. How much?

I have a "new" distributor that I am trying to recurve, but it would be nice to have a complete "smog" distributor, too. I tried making springs for it. They work, but not quite right. With one spring broken for years, it would idle cold when I was tuning up, but once I drove away, the one spring could not drag both weights back unless I slipped the clutch to bring the rpms down. I always thought it was worn carb shafts. But when I finally installed glands on the shaft with packing, it did not correct the problem. Finally someone at a local car show suggested it might be the distributor.

Regards, Joe

[originalowner]

I want one of these! I have been thinking about this as well. It would be easy to create one on paper but getting one to stay on is another story.

Solex68
_________________
Hi Greg,

OK, so the commercial timing tapes are printed on vinyl to stand up to conditions in the engine compartment. I agree that paper would not last very long. Some of the comments said that the tape did not stick very well at 5000 rpm. I priced vinyl sheets for laser printers between 80¢ and 2.80¢ in packages of 100. A little pricy unless you need the entire ream.

What I do have on my shelf is transparency sheets for overhead projectors when I used to give presentations to the customer. I was worried that you would not see the scale against the dark Nissan blue that my new harmonic balancer is painted. But I decided it was worth a try.

I generated the tape and printed it on a transparency. It seems to work fine. If you don't mind painting your vib damper, it would contrast well with any light color. The only question now is glue. I am thinking maybe duco cement (airplane glue) might work as well as any. The damper is 16.1" in diameter, so an 11" strip will wrap most of the way around. That way it will not be so sensitive to centrifugal forces trying to rip it off. With a 3" tail on each end (the tape is 3.5" long using the layout in the photo above) there should be ample length to glue the ends if not the middle, (worried about seeing the glue) and room to tape it on too, for alignment.

Anyone who wants one, send me your address and I will mail you one.

Regards, Joe