[Gubi]

Owner's manual says 87 AKI for a stock US '74. With a more aggressive timing map, yeah, you should definitely be running premium. The Euro 2L with 40 max advance just says "premium fuel recommended" though I don't see an octane spec.

Saffa, are you running higher compression than stock? I suppose it could be pre-ignition, which is very different from knock/detonation and would not be impacted by the ignition timing. That would be pretty bad. Preigntion could be caused by too hot plugs, carbon buildup, too high compression, too low octane, or running too hot.

If you're running stock compression and 91 octane gas then preignition seems unlikely. But again, not an expert, and I'm just guessing here without actually hearing the noise.

 

[Saffa]

Okay, thanks everyone for the input here. I think perhaps I was getting a bit too paranoid reading about the dreaded ping. Today I put everything back as it was in my first post and reinstalled my Spica air filter. driving the car now I can't hear the rattle/ping I mentioned which makes me think that @4sfed may have been right!

 

[Gordon Raymond]

As an aside... { He is ALWAYS right } You can ask how I know if you wish.

 

[vintagemilano]

As an aside... { He is ALWAYS right } You can ask how I know if you wish.

How do you know he is always right?….

 

[Gordon Raymond]

As you get to know Jim, he will show you very specialized Alfa engineering projects you never imagined possible. Better still, they work well.

New or old, he has studied it to make it better.

Review his discussions on engine building for the fastest Alfa at Bonneville. Jim builds amazing stuff. I build Alfa oil pumps. Very good ones. Jim has built some considerably better. His engineering expertise keeps him thinking about things most never consider.

 

[Veep]

As you get to know Jim, he will show you very specialized Alfa engineering projects you never imagined possible. Better still, they work well. View attachment 1897900
New or old, he has studied it to make it better.
View attachment 1897901
Review his discussions on engine building for the fastest Alfa at Bonneville. Jim builds amazing stuff. I build Alfa oil pumps. Very good ones. Jim has built some considerably better. His engineering expertise keeps him thinking about things most never consider.

I am looking at other design cam followers there . any info on that?

 

[Gordon Raymond]

Secret Jim Steck stuff. You need to call him for information. I remember he told me "expensive".