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Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Oct 28, 2025 10:21 pm
by IanM
I assume they're handed depending whether your car is LHD or RHD?

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Oct 28, 2025 10:22 pm
by matteo68
All the factory-built SRs were LHD

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Oct 28, 2025 11:00 pm
by IanM
What's an SR? No mention of that model in any of the Paul Frere's books if I'm not mistaken.

Back in the day, a factory roll cage could be purchased through the race department.

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Wed Oct 29, 2025 1:26 am
by Nine One One
Sport / Racing

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Wed Oct 29, 2025 7:02 am
by Leirbag
matteo68 wrote: Tue Oct 28, 2025 9:49 pm Image

This one? Diagonal going the other way again - same as PET illustration...
Yes, that's the one. Porsche offered the kit for home installation or at the factory, and I feel like the factory installation included the reinforcement in the opposite direction, perhaps to differentiate on a racetrack, both version (M491 and customer) ?

(I doubt they were really focused on aesthetics at that time, but you never know?)

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Wed Oct 29, 2025 7:12 am
by Leirbag
Darren65 wrote: Tue Oct 28, 2025 10:05 pm Take your pick....

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The first 3 on the right : 0910, 0908 et 0870 : factory M491 kit

The other 3 : 911-Kubero (red), 911 030 1016 (white-red) et 911 250 0335 (Kremer green) : either factory kit or own kit

From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Wed Oct 29, 2025 7:47 am
by matteo68
Nine One One wrote:Sport / Racing
The official term for the 1972 model year was 911 S Coupe M491 Competition or Racing version.

S-R was an unofficial term like ST for the 1970-71 2.3 911 S (which was assembled from various kits which could be ordered from the factory). Because the 21 1972 911 2.5 911 S were developed for Group 4 racing the 'R' for Rennausführung was accordingly adopted in some circles to identify them - this is the fzg-a (or build sheet) for 1687, the last S-R built:

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Also the 1973 2.8 RSR was never officially known as that - the official reference was M491 Carrera RS 2.8l - RSR was a term coined by Erwin Kremer, the R for Rennausführung again.

From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Wed Oct 29, 2025 10:39 am
by matteo68
My 1971-dated "K Kurz Hessental KG" 110l fuel tank came with an original 100l fuel sender and 110mm diameter alu Blau finned fuel cap, all super cool items.

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Increasing the cool factor further, I have just learned via another read through of Flunder's excellent / reference ST build thread "Another Hot Rod" on ESR that the Blau cap goes by an early part number for the Carrera 6: 906.201.023.04 "Tank closing"...

From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Nov 11, 2025 5:29 pm
by matteo68
Today's job: turning an original SWF / genuine Porsche washer bottle into an oil breather bottle and trial fitting it in the front-right corner of the engine bay:

Turns out - by reference to the many photos I have of original SR engine bays - that it sits flat on the cross-member so we had to cut the tab off the bottom and the neck off the top and then reprofile the strengthening strip on the top of the cross-member to get it to fit snugly:

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Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Nov 11, 2025 5:49 pm
by matteo68
Next we need to fabricate some 90-degree brackets and weld these on to hook the 356 rubber battery strap onto, create a new hole in the shoulder of the bottle for the breather pipe to go into and plug the other two holes

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Nov 11, 2025 6:25 pm
by majordad
See you at Strahle, we arrive Thursday

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Nov 11, 2025 6:43 pm
by matteo68
See you there Dave!

I'll have these with me to hawk around the tables!

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March'67 dated so all correct for 906 & 911R...

From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Tue Nov 11, 2025 6:52 pm
by matteo68
Bosch transistor ignition modules, ballast resistors and S/121 AA Marelli dizzy - see here: https://auction.nicola-ac.de/catalog134 ... y=&filter= for twin-plug set up...

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An NOS set of modules, resistors and coils sold on Ni-Cola for €7,000 4 years ago...
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Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Thu Nov 13, 2025 10:22 am
by matteo68
First job of today: fitting the Bosch push-on / quick disconnect twin CDI cut-off switches (part number: 901.602.702.00) either side of the ignition lock:

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(old instruments and alu trim panel mocked up to aid correct positioning)

Re: From ‘72T to 2.5 S-R: GeLo Racing #44

Posted: Thu Nov 13, 2025 1:40 pm
by Lightweight_911
matteo68 wrote: Thu Nov 13, 2025 10:22 am First job of today: fitting the Bosch push-on / quick disconnect twin CDI cut-off switches (part number: 901.602.702.00) either side of the ignition lock:
I'm sure you intentionally posted the incorrect part number to see if anyone was watching ... :wink:

- that part no.is for the CDI box.

The Bosch 2-pole pull-switches that Porsche originally used for isolating the 2 ignition circuits on the 911R, 904, etc was the same as used in 356/356A models (for fog lights, fuel pump, etc) - part number 644 613 501 01.

This version had the screw terminals but Porsche later (in ~ 1970 from memory) used the version with 'spade' terminals as in your picture (can't remember the Bosch part number offhand).

Apologies for the 'side track' ...

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