Is it an S or an SC??

[Haitham]

Thanks so much Peter. Great photo explaining where the air pump sits. Read somewhere that these were sometimes removed as it gives an extra few bhp. What did it do? And many thanks for the compliment. Scarlett as she's affectionately known will be chuffed to bits

The pump was driven by a belt from the crankshaft pulley and was designed to inject air into the exhaust gases in an attempt to meet emissions regulations by providing fresh air as a source of oxygen in the exhaust port to assist with combustion of any un-burnt hydrocarbons. Adding fresh air to the exhaust gases also gave the impression that the emissions were diluted and therefore somehow less - A Neanderthal version of VW's "cheat" software many years later.....
The "additional" bhp referred to will basically be those saved by the engine not having to power the air pump.
Many owners removed the drive belt (as in Peter's picture), but through time most removed the whole pump to also save some weight. When doing this, the pipework on the bottom of the engine into the exhaust ports should be removed too and the injector holes plugged with grub screws.

Perfect. Many thanks. Learning slowly n

 

[chrishak]

Thanks so much Peter. Great photo explaining where the air pump sits. Read somewhere that these were sometimes removed as it gives an extra few bhp. What did it do? And many thanks for the compliment. Scarlett as she's affectionately known will be chuffed to bits

The pump was driven by a belt from the crankshaft pulley and was designed to inject air into the exhaust gases in an attempt to meet emissions regulations by providing fresh air as a source of oxygen in the exhaust port to assist with combustion of any un-burnt hydrocarbons. Adding fresh air to the exhaust gases also gave the impression that the emissions were diluted and therefore somehow less - A Neanderthal version of VW's "cheat" software many years later.....
The "additional" bhp referred to will basically be those saved by the engine not having to power the air pump.
Many owners removed the drive belt (as in Peter's picture), but through time most removed the whole pump to also save some weight. When doing this, the pipework on the bottom of the engine into the exhaust ports should be removed too and the injector holes plugged with grub screws.

Perfect. Many thanks. Learning slowly n

It's a steep learning curve with these cars - wait 'till the subject turns to 'which oil should I use?' or even (heaven forbid), 'how best to jack it up?'

 

[Old and Slow]

Just catching up on the thread, your engine compartment is immaculate, but running too fast to count the fan blades[]
You can see the small finned alloy block tucked away on the LH side, this is the CDI, so definitely an SC, if you weren't convinced already.
Both General Motors and Toyota also used air pumps very successfully to burn off any unburnt fuel in the exhaust and meet US pollution limits, but it is a myth that it only dilutes the exhaust gases; not true of course. I've heard that the air pump takes between 1 and 2 bhp to run, don't know whether this is accurate.
Good luck with Scarlett - I hope you enjoy the drive.
Philip

 

[Haitham]

In Porsche GBs defense, I believe they acknowledge there may be errors. Providing you can verify the error or errors, I'm sure they will adjust accordingly.

ps. welcome to air cooled ownership enjoy .... once bitten for ever smitten!

Many thanks. I'll do just that. I certainly have the bug ??

 

[Haitham]

Just catching up on the thread, your engine compartment is immaculate, but running too fast to count the fan blades[]
You can see the small finned alloy block tucked away on the LH side, this is the CDI, so definitely an SC, if you weren't convinced already.
Both General Motors and Toyota also used air pumps very successfully to burn off any unburnt fuel in the exhaust and meet US pollution limits, but it is a myth that it only dilutes the exhaust gases; not true of course. I've heard that the air pump takes between 1 and 2 bhp to run, don't know whether this is accurate.
Good luck with Scarlett - I hope you enjoy the drive.
Philip

Thanks Philip. I think I'm well and truly convinced it's an SC. Whole lot of people said it couldn't be an an sc being a 77 on a Facebook group I'm a member of but I think that's been cleared up too. Wish I could lay claim to tidy engine bay but the last owners work. I just have to keep it that way ??

 

[chris.hevey]

Also worthy of note is the bright new looking pipe work to the right. This appeared in my engine after I had it rebuilt and I was assured by RPM who did the work this was to do with hydraulic valve lifters. These are either a feature of an older design or something that appeared in the later 3.2 litre engine, i forget which, but not an SC thing. Picture attached

hopefully others can explain what it is I'm talking about

 

[chrishak]

Not for hydraulic valve lifters (they are solid lifters), it'll be a feed to the 3.2 Carrera hydraulic timing chain tensioner, a common (and very sensible) mod for earlier air-cooled engines

 

[chris.hevey]

That's it! Hydraulic chain tensioner things. I knew someone would know WTF I was on about, even if I didn't. []

 

[Haitham]

Not for hydraulic valve lifters (they are solid lifters), it'll be a feed to the 3.2 Carrera hydraulic timing chain tensioner, a common (and very sensible) mod for earlier air-cooled engines

Good call. Has had the hydraulic tensioner upgrade - even if I don't know what it is lol