Puzzle

Perhaps you're experiencing relativistic effects, Phil.  Einstein proved that as you approach the speed of light time moves more slowly.  Maybe since your car is is so fast the universe just decided to give you a head start on relativity - or not.

Seriously, I'd look into the tach first.  Find someone with a dwell tach and see if it matches the one in the car.

I don't think it can be just a different  R&P.  

I ran the numbers, using the gears listed.

At 3000 rpm

4.12         4.37         4.86

18             17              15

28             27               24

45             43               38

67             63               56

At 4000 rpm

89            67                63

The only way I get to the speeds you listed is with the following:

4.12 r&p

3.75  1st

2.46  2nd

1.56  3rd

1.04  4th

This also gives exactly 70 mph at 4000 rpm.

I don't think this is your problem, I'm betting on a tach issue.

When I look at the speeds at 2200rpm, they match exactly what you have listed!  

My money is on the tach. I’d bet a dinner you are reading 25% high because you are on the 6 cyl setting.

If that’s the case, at 70 mph, you’re really turning 3000 RPM, not 4000.

I’ve been looking at the same thing. But I would think that it would be 33% high. Why is it 25%.

What Stan says, except I think it's 33%.

2200 rpm x 1.33 = 2926 rpm  

3000 rpm x 1.33 = 3990 rpm

Close enough for government work.

33% just doesn’t work.

Don't overthink the math part.  Just check the setting and I'll bet that's it.

@550 Phil posted:

I’ve been looking at the same thing. But I would think that it would be 33% high. Why is it 25%.

Because I posted from my phone while wiring a light. As Lane says, just check the tach. You’re fixating.

Thought it would come to this. Going to buy a gauge to tell me the true rpms.

@550 Phil posted:

33% just doesn’t work.

I did the math for you above.  Your engine is really turning a little north of 2200 rpm when you are going the speeds you posted.  I ran the numbers through Weddle’s gear calculator.  

@550 Phil, Here is the worksheet

@Lane Anderson posted:

Don't overthink the math part.  Just check the setting and I'll bet that's it.

Exactly as I posted on the other thread the other day. Reset the tach whenever you get to it.

I posted a link to the tach programming instructions. It's not a big deal.

@550 Phil posted:

Thought it would come to this. Going to buy a gauge to tell me the true rpms.

Why?

Just go through the tach setup @DannyP linked. If it's set to anything besides 4-cyl, then reset it. I'd be very surprised if it's not set to 6-cyl.

If the tach is set on 4-cyl already, then buy the timing light Danny linked several days ago and check it. It's entirely possible that the tach could be bad.

Your gearing is right, almost for sure. Your speeds match your stated gears, just at the wrong indicated RPM.

It's really very simple.

Your gauge could need one of two possible "programming buttons". This is the one I have, it has a 1/8" headphone jack:

https://speedhut.com/gauge-acc...-el-lit-gauges-only/

It could also possibly have this style(you just need to look at it):

https://speedhut.com/gauge-acc...-for-led-lit-gauges/

You just need to look at the back of the tach to find out which.

This is basically the tach we have, it just has a custom silk-screen face.

https://speedhut.com/gauge-app...?dd-link=0kx6p31reeb

This tach will work with a 1 to 12 cylinder engine. Here's the instructions on setting it:

https://speedhut.com/content/i...D%20Instructions.pdf

The tach is set by PPR(pulses per revolution). If it is reading high(which it is) it is set TOO LOW. To make it read correctly, it needs to be set to 2PPR, and I'll bet it is set to 1PPR currently. Note highlighted text.

It doesn't matter WHY this is so, it is a simple error. All will be well once this is fixed.

Just look at the back of your tach and get back to us.

Thanks guys. Back in Va Beach. Next time I’m in Cville I’ll pull the tach. I did get this done while I was in Cville. No more warped rotors. Drilled and slotted rotors with ceramic brake pads on all 4 wheels. For just $350 from summit. If I do have to take the Fiat to Wytheville, I’ll be ready. If the weather is nice I’ll drive the Spyder. I actually feel better about driving it on the highway since I know now I’m not really at 4000 rpms at 70.

I took a picture of the backside of my tachometer. The circled area is where the programming switch harness plug goes.

Thanks Danny.

Ok. So I’m finally back in Charlottesville where I keep my Spyder and my tools. When the car’s tach reads 2000 rpms I’m really at 1550 rpms. So when I’m at 70mph and the car’s tach reads 4000 rpms I’m really at about 3100 rpms. Greg is sending me the wire so I can reprogram it. I used to tell people that my car sings to 7500 rpms in first 3 gears. Obviously that’s a bunch of crap.  Greg told me the other day that Outfront limits the engine to 6200 rpms. I’ve been living a lie.

"I’ve been living a lie."

Most of us do with these cars...

Yes, true enough, but living none the less, and quite well by all accounts.  You are forgiven.  We understand.

Excellent news, Phil. I'm looking forward to seeing you in it in Wytheville later this month.

@Stan Galat posted:

Excellent news, Phil. I'm looking forward to seeing you in it in Wytheville later this month.

As am I.  I think this is gonna be epic.

If I can find a 3 hour window on Wednesday and a 3 hour window on Sunday I’ll drive the Spyder. If we expect rain on any of the drives I might have to find a shotgun. It’s going to be too hard to navigate the route and drive in the rain at the same time.

I guess.

The thing is (obviously) not limited to replica owners, but at the bottom of the well It is a get-together of likeminded owners, past owners, or future owners, though.

I can't imagine owning one (built specifically for driving in the mountains), having it in prime operating conditions, storing it a couple hours away and not bringing it... but you do you.

Das Blaue Biest is ready and willing to perform as the chariot for someone who may need a right seat to sit in.  I can also carry tools, if necessary.

Lane. Please bring tools. If the weather is cooperative I’ll have room for a duffle bag, my car cover and that’s about it in a Spyder. I’ve got a big radiator in the front so no frunk. I probably won’t be the only one that may need tools. Got a feeling that Danny may bring a wrench or 2.

Back in Charlottesville.  There are 2 inputs on the back of the tach.  The one for programming is on the driver's side.  So my tach was programmed at VMC for 1.5 PPR (pulses per revolution).  It should have been programmed to 2 PPR.  So speeds at 3000 rpms are now:

1st 19mph

2nd 30mph

3rd 48mph

4th 71mph

Exactly what Rick calculated them to be.  Math is awesome.

@550 Phil, now you really get to rev that motor up!

@LI-Rick posted:

@550 Phil, now you really get to rev that motor up!

I was constantly bouncing the tach off of 7500 rpms. Of course it was all a lie. Now it’s more like 6000 rpms.

@550 Phil posted:

Lane. Please bring tools. If the weather is cooperative I’ll have room for a duffle bag, my car cover and that’s about it in a Spyder. I’ve got a big radiator in the front so no frunk. I probably won’t be the only one that may need tools. Got a feeling that Danny may bring a wrench or 2.

I have some stuff, but not a full complement. I should have got at least a 20 foot trailer instead of a 16. It all fits with the race car in there, but that's only 10 feet long.