How in heck does this thing work? (Nu rex)

[Terry, NJ]

Just got home from a friend's. He wanted some help timing his Huckster, (Nice car) So when Joe started to time it it seemed to me to be off, like about one cylinder out of phase. He used this crazy Nu Rex cam wrench. But wait! I set the timing pin for number one cylinder, not number four! How does this thing work?When he got done, this engine, predictably, wouldn't start. He said time it your way! So I put it on number one and timed the cam just so the engine fires just as it goes past the the last part of numbers one contact. Voila! It started up and ran nicely. so what gives with the Nurex wrench. I timed it with finger feel.
Terry

[nkaminar]

Yeah, that's the way I have always done it, by feel or just looking at the points. Sometimes I will use an ohm meter.

I think the wrench is supposed to put the point's cam in the right position by the orientation of the wrench. If everything else if 100% then it will work. But why not just go to first principles and time the engine by the position of the rotor and the opening of the points?

[Patrick L.]

Originally Posted by nkaminar

Yeah, that's the way I have always done it, by feel or just looking at the points. Sometimes I will use an ohm meter.

I think the wrench is supposed to put the point's cam in the right position by the orientation of the wrench. If everything else if 100% then it will work. But why not just go to first principles and time the engine by the position of the rotor and the opening of the points?

Yep.
Left lever up
Set points
Find dimple.
Turn cam
Tighten cam screw

This has been working for 90 yrs

[marty in Ohio]

I've found the Nu Rex tool to be quite helpful. Of course you have to set number 1 cylinder at TDC and then you rotate the wrench. The tool says to stop when the indicator points to number 4 plug. I wonder if that's where Joe went wrong.
Marty

[aermotor]

Here I go again with less experience than most others. I like because I believe it comes closer because of the width of the rotor contact. I am not clear as to the position of the rotor contact to the distributer contact the original way.

John

[ETAModel]

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Another newbie who used the Nu Rex wrench and it worked fine. I did watch the YouTube video first. I think that helped me.

[katy]

Back in the '50s I was taught by an old timer: spark advance lever all the way up, timing pin in the dimple, points just starting to open for #1 cylinder, tighten cam screw, Bob's your uncle.
Works every time.
Back then we had no manual, Nu-Rex hadn't been thought of.

[Eccentric Old Guy]

I notice that Paul Shinn uses the Nu-rex, and he times his engine to one notch down. Most everyone else has the spark lever all the way up....including the nu-rex manufacturer's video. pros and cons anyone?

Looking for discussion about this.

Also, when the spark lever is brought down for normal driving, the spark actually goes from TDC to before TDC for driving....am I correct about that? In Shinn's video, he explains how he times the engine to after TDC, so that there will never be a backlash from hand crank starting......but, if that is so, it seems like one notch down will actually mean it would be more likely to get a kick-back while hand crank starting.

What am I missing here?

eog

[Dick M]

Interesting thread. I have used the NuRex tool as well. Started with getting the timing pin in the dimple. Then rotate the tool until the arrow on the leading edge makes contact with #4 terminal on the distributor body. I then double check the timing by having the spark advance all the way up, connect a test light to the point arm, turn on the key, bring the spark advance down and count the clicks until the test light comes on. The light should come on in the first 2 clicks. I have found when using the NuRex tool the light is on with the spark advance all the way up. That tells me the spark is not sufficiently retarded. I am not a big fan of this tool. It's close, but not dead on. I just use the test light method with great results.....

[Terry, NJ]

I forgot about two things; Two revolutions while free, of the cam clockwise. Then put the wrench in final position, which we did. Now what in hell did that do? And advance the lever on the column 2 notches. That I get, you're putting two notches of advance into it before you tighten anything down. If I remember correctly, 2 notches is 4 degrees, possibly a little much for a model A. Wait a minute' that is 4 degrees advance isn't it? OWWW My head hurts from trying to see all this in my mind. Someone far sharper than I, will know. Going over it in my head, I still don't understand what this Nu-rex thing does for you, cute cam wrench, except the notch is in the wrong place. And I trust Paul Shinn.
Terry

[Curtis in MA]

Paul times with the spark one notch down, then when he hand cranks the lever is fully retarded.

[Eccentric Old Guy]

Originally Posted by Curtis in MA

Paul times with the spark one notch down, then when he hand cranks the lever is fully retarded.

OK....that makes sense.

So full up means the spark happens further past TDC than it would have been if timed with spark lever all the way up. I think Shinn meant to be clear about that, but it wasn't so clear to me, from his video.

Everyone else who times #1 at TDC with spark lever all the way up, therefore runs the risk of a kick-back while hand starting with the crank handle. Might not make any difference, or very little difference when starting (and driving) using the electric starter motor.

eog

[Patrick L.]

Originally Posted by Eccentric Old Guy

I notice that Paul Shinn uses the Nu-rex, and he times his engine to one notch down. Most everyone else has the spark lever all the way up....including the nu-rex manufacturer's video. pros and cons anyone?

Looking for discussion about this.

Also, when the spark lever is brought down for normal driving, the spark actually goes from TDC to before TDC for driving....am I correct about that? In Shinn's video, he explains how he times the engine to after TDC, so that there will never be a backlash from hand crank starting......but, if that is so, it seems like one notch down will actually mean it would be more likely to get a kick-back while hand crank starting.

What am I missing here?

eog

Each notch down of the left lever is 2-3* of advance, so, if base timing is set in that manner the timing is retarded when the lever is fully up. In other words, if lever is down 2 clicks when timing is set then when lever is full up the timing is retarded [ ATDC] by 4-6*. The engine should hand start just fine with little worry about a kick back. A kick back usually doesn't occur until timing is about 10* [ or more] BTDC.

If an engine base timing is retarded when lever is full up then the total advance when lever is full down is decreased by that amount. The full lever movement should be 40*, so, with lever full up and timing is set 5* retarded then the actual total advance will be 35*. Thats actually better as far as I'm concerned as I don't think these engines need 40* of advance.

[jb-ob]

Men aren't good with asking directions or reading them.

And it's still just a Ford.

[Eccentric Old Guy]

If there are 10 lever notches, and there is a total of 40° possible advancement in the timing, then 1 notch is 4°......right or wrong?

eog

[MrBruce]

I've used it to show someone and it does work if you follow the directions. You stop at the number four plug and it says "do not move it backwards" The timing isn't like I set mine, but for beginners it does work.

[Eccentric Old Guy]

To get the timing absolutely perfect, the only way to do that is a perfect TDC in #1 cyl, and a timing light that will determine the very instant when the points open.

To find perfect TDC, the timing pin will serve as a reference point, but removing the spark plug in #1 cyl, and rotating the crankshaft while observing the piston through the spark plug hole, is the only real way to find a perfect TDC.

Is there a more perfect way to do it?....and, is it relevant to a good running model A engine?

Seems to me there is a little wiggle room for getting a good running engine, specifically because the spark advance is manual, and not centrifugal, vacuum, or some other form of automatic adjustment.

eog

[aermotor]

Originally Posted by Eccentric Old Guy

To get the timing absolutely perfect, the only way to do that is a perfect TDC in #1 cyl, and a timing light that will determine the very instant when the points open.

To find perfect TDC, the timing pin will serve as a reference point, but removing the spark plug in #1 cyl, and rotating the crankshaft while observing the piston through the spark plug hole, is the only real way to find a perfect TDC.

Is there a more perfect way to do it?....and, is it relevant to a good running model A engine?

Seems to me there is a little wiggle room for getting a good running engine, specifically because the spark advance is manual, and not centrifugal, vacuum, or some other form of automatic adjustment.

Piston movement is nearly undetectable moving the crankshaft a few degrees left or right. I think we are overthinking getting within a gnats a**. After starting the advance is determined by depending on the ear and feel, which will not be able to detect a couple degrees either way.
John

[Rob Doe]

x2 on many of the above comments. Here is a couple things I didn't see mentioned. I'm adding them for other newbies like myself that may read this thread in the future.

The Nurex timing wrench works fine, especially for an absolute beginner, it prevents the person from misinterpreting the word 'opposite' found in several written descriptions of how to time the Model A. Misinterpreting the word causes the newbie to misalign the rotor by 180 degrees.

There are written descriptions of how to time the Model A that do not correctly describe how to remove the gear lash. If you watch the video on the Nurex web site, you'll learn to remove all the lash from the gears in the proper manner/direction before tightening down the cam lock screw.

I believe there are 10 positions for the spark lever, but have counted 11 a couple times ??. If 10 is correct then each notch is 4 degrees crankshaft timing?? If 11, then its 3.64 degrees. The movement of the advance/retard lever moves the distributor timing only 20 degrees. This is because the distributor rotor turns at 1/2 the speed of the crankshaft.

Some cars have high compression heads and because high compression means the fuel mixture burns faster, their engines can only use around 20+ degrees timing advance. Old timers have been known to time the engine at 3 notches down to prevent the car from being driven with harmful advance settings.

I hope this helps someone.

[KR500]

I have purchased a couple of the NuRex offset bent wrenchs, from Brattons. I went to use it on a customer car to try it and its off. I compared two wrenchs and the wrench I tried is 90 degrees off. I contacted Bob Gray of NuRex and sent photos of the two wrenchs showing the wrong offset. He said I will send you a replacement which he did and said throw the other wrench away. Apparently when they were putting the wrench in a hand or press forming jig they reversed the blank and put the offset on wrong side. If you suspect you have wrong wrench compare the bend to perhaps the NuRex video.