Educate me, Please
 

What are the history and reasoning for these been used on race engines back in a day?

Thanks in advance

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Standard equipment timing sprocket for the earliest 911 engines.
Generally not used in race engines. Too much unnecessary weight.
I guess someone may have felt they offered a more secure method of holding the timing pin?

"Someone" being factory? I was told they came Only on racing engines.
This pair came off of 935 engine.

I have the same in my 67S, I guess you can shave a few grams by using the later ones.

andy

The ether is full of legends about Porsche parts and what can on what engine and in what car.
The "truth" is: I have 25+ sets in a box in my shop.
Zero came from a factory race engine.
If this legend was true, I have a plethora of valuable race parts that need to be marketed to the gullible.

Weight was only one possibility for redesigning the hub. The chain drive mechanism is already overweight adding to the parasitic losses.. That is why the factory fitted aluminum parts wherever they could. The later open hub may also be an attempt to minimize damage in the case of cam seizure/stoppage. The full circle hub will not break under heavy loading (catastrophic failure) and the teeth on the later version will shear off mitigating collateral damage.

Yep, I have some of those. out of a early engine (think it was 68-or 69 engine).

John

Yay...so your credentials for speculation are better ranked than mine. congratulations!

..and all I asked for was the FACTS not an opinions.

It's a conversation...trying to limit the responses you get seems a little counter productive.

I'd listen to Henry. If he tells you what it is, he's giving you advice on decades of experience. I'm sure he's pulled apart exponentially more engines than I, and I've pulled apart a lot.

No one has to listen to my noise....I'm just rattling on about the cars I love.
Believe me, investigate what I say, ignore me completely or challenge what I offer.
It makes no difference to me but I will keep offering the noise.

We appreciate all the "noise" you care to share with us