Please Help Indentifying This IWC Ingénieur Watch

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Friends, I just bought this IWC from a trusted seller. The watch is in excellent condition but is without box and papers. The only numbers I could see on the back is 2405746. It’s a screw down crown 34 mm watch.

I want to know the exact model number of this watch and the caliber inside the watch. Please help. Regards
 
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In 1976, at the height of the Quartz crisis, IWC introduced a very small production run of Gerald Genta-designed "Jumbo" Ingenieurs. They were 38mm, massive (especially for the time), and were powered by the final iteration of the iconic cal. 85x series, the 8541ES. It was, of course, designed to resemble the already successful Audemars Piguet Royal Oak, but with IWC's superior technical capabilities. It was the reference 1832, and they are highly sought-after by collectors today.

That was the predecessor to your model, the so-called "skinny" Ingenieur, which is either a ref. 3505 or 3506. The model was introduced in 1983, and was powered by the caliber 375, based on the ETA cal. 2892. The 3506 (cal 3753) was produced from 1985 to 1989. While these models had antimagnetic qualities, they were only half of the capabilities (40,000 A/m) of their predecessors. This, coupled with the significantly smaller size, and downgraded, derivative (i.e. not "in-house") movement, makes them generally less attractive to many collectors.

The "SL" is thought to have originally meant "Steel Line", referring to the integral bracelets, but as there is evidence that they were subsequently sold on straps as well, it evolved into "Sports Line".
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Thanks for your response dear. Is there any difference in 3605 and 3506 models? I meant movementwise.
 
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As noted above, the base movement was the same (cal. 375), but the 3506 featured a slightly refined version (cal. 3753). What refinements were made, I do not know.
 
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Okay. I read on IWC forum that 3506 had a solid gold rotor, I don’t know what did that mean.

Also the seller, a reputed person, told me that he originally bought this watch from the boutique and since then it’s not serviced even once.

He informed me that he got all the tests done in January this year and the watch is running +1.5 spd and amplitude and oscillation deviations are within permissible limited therefore no service needed!

He wore it 10-15 days a year as he has a huge collection. He belongs to the school that teaches unless watch performance is beyond specification, there is no need for service at all.
 
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The school that he belongs to is not teaching well, at least in this case. Oils dry out over time, to make the most obvious point, and it would be a mistake to wear your new watch regularly without having it serviced.

With regard to the rotor, it may well have some gold content, but this was largely marketing, and "solid" tells you nothing about whether it is 2k or 18k.
 
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Okay. I read on IWC forum that 3506 had a solid gold rotor, I don’t know what did that mean.

Also the seller, a reputed person, told me that he originally bought this watch from the boutique and since then it’s not serviced even once.

He informed me that he got all the tests done in January this year and the watch is running +1.5 spd and amplitude and oscillation deviations are within permissible limited therefore no service needed!

He wore it 10-15 days a year as he has a huge collection. He belongs to the school that teaches unless watch performance is beyond specification, there is no need for service at all.

This watch is desperately due for a full service. Also, for the benefit of the forum, please post photos of the movement and the inside when you have the opportunity.
 
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This watch is desperately due for a full service. Also, for the benefit of the forum, please post photos of the movement and the inside when you have the opportunity.
Yes I’ll do that. Regards
 
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The school that he belongs to is not teaching well, at least in this case. Oils dry out over time, to make the most obvious point, and it would be a mistake to wear your new watch regularly without having it serviced.

With regard to the rotor, it may well have some gold content, but this was largely marketing, and "solid" tells you nothing about whether it is 2k or 18k.

Yes are right indeed. I do agree with your conclusion. Yet I think if I got it in a near mint condition for less than $1000 it’s not a bad bargain either. I’d appreciate your opinion again. Regards
 
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The specifications given on IWC forums are;
  • automatic calibre 375 with ball bearing rotor and date display
    • based on ETA production (calibre 2892)
    • diameter: 28.00 mm
    • height of movement: 3.75 mm (hence IWC's naming of the calibre)
    • number of jewels: 21
    • frequency: 28,800 A/h = 4 Hz
    • balance spring: flat
    • fine adjustment: Etachron
    • total production: 9,940 pieces (only part of which was used on Ingenieur models)
  • tripartite screwed case
    • steel and mixed cases water resistant to 12 atm
    • gold cases water resistant to 6 atm
    • top part with bezel: flat surface with 5 recesses (for screwing tools) in stochastical position
    • amagnetic to 40,000 A/m, movement protected by Farraday's cage made of soft iron inner case and soft iron dial bottom
    • Glass: sapphire
  • Ingenieur- and SL-Logo with scripture AUTOMATIC above index at 6 o'clock
That’s what my search at google helped me get for this watch. Hope it may help somewhere.
 
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The school that he belongs to is not teaching well, at least in this case. Oils dry out over time, to make the most obvious point, and it would be a mistake to wind your new watch regularly without having it serviced.

FIFY.

You can wear an unserviced watch as often as you like if it isn't running. 😉 😜 😜 😜
 
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Yes are right indeed. I do agree with your conclusion. Yet I think if I got it in a near mint condition for less than $1000 it’s not a bad bargain either. I’d appreciate your opinion again. Regards

My first vintage love was the first generation ref. 666 Ingenieurs, and I have owned more than a few 666 and 866 models. I never developed an interest in the later models, though, so my knowledge of the market is very limited. The price that you paid sounds reasonable, and especially given the condition claims, but I cannot be more specific.

The reference that you bought are nice watches, and there is nothing wrong with ETA-based calibers. But given the importance of IWC, its iconic Ingenieur model line, and the cal. 85x movements, they will never be thought of, or collected with the reverence and passion as the earlier variations.
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FIFY.

You can wear an unserviced watch as often as you like if it isn't running. 😉 😜 😜 😜

But it’s running 1.5 spd and running well.
 
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My first vintage love was the first generation ref. 666 Ingenieurs, and I have owned more than a few 666 and 866 models. I never developed an interest in the later models, though, so my knowledge of the market is very limited. The price that you paid sounds reasonable, and especially given the condition claims, but I cannot be more specific.

The reference that you bought are nice watches, and there is nothing wrong with ETA-based calibers. But given the importance of IWC, its iconic Ingenieur model line, and the cal. 85x movements, they will never be thought of, or collected with the reverence and passion of the earlier variations.

I do agree sir. My passion this time was limited to owning an IWC watch with “International Watch Co.” Written on the dial with 37 mm or less vintage dial in good condition. That being fulfilled I’m happy. Now you’ve guided me to seek further next time... I read your comments with interest and learn a lot. Thank you for imparting me such knowledge. Regards
 
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You are most welcome. I'm glad that you are happy, and look forward to seeing your next acquisition!