Hi Ken

not just jag

Guzzi too


"Tappet clearances for two and four valve engines

Two valve engines

Tappet clearances for the Guzzi big twins should be set to 0.20mm for the inlet and 0.25mm for the exhaust. This also applies to the "modern" Guzzis such as the Sport 1100, Cali 1100i and V11. The factory settings for these bikes are 0.10mm and 0.15mm respectively, but this is to try and reduce engine noise to meet US emissions regulations. With tappets set this tight the engines have trouble ticking over and running cleanly at low revs."

"Four valve engines

These should be set as per the factory settings of 0.10mm for the inlet and 0.15mm for the exhaust. For highly stressed engines in racing applications with borderline cooling to the heads wider settings may be necessary. Please call Raceco on 01394 383499 for more details on this."

Sean

Sorry if you've already said it, Joe, but did you check the inside of the rocker covers for signs of contact with the rocker arms whilst you had them off? however careful you've been this time, if they've been distorted before, or if your gasket is a bit worn out (although I think you said they were new?), then it won't take much to bring them into contact. It doesn't take too much to 'reshape' them, if that has happened.

No point referring to Jags, Guzzi’s or any other engine. So a 2cv engine should also change exhaust valve clearance because others do. Another question is who is recommending these changes? The people behind the development of the engine, I don’t think so. Please tell me that Citroën was wrong when recommending setting the exhaust valve to 0.20 mm instead of 0.25 mm

I'm kind a with TheViking on this one. It's been up for discussion before here, but I'm still not convinced that it is necessary to not follow the original settings. But then I have limited years of knowledge with A-models, so I have great respect for the people with much more experience.

But the argument used by other engine makers are not very interesting. Arguing that lead-free fuel have less octane-number is not relevant anymore. Here 98 oct. is normal. The Gussi-thing...... I seriously doubt that the engineers of the 2CV-engine had noise restrictions hanging over them when they decided the 602 should have the settings it has from factory.
And 2CV racers.....I dont see what that has to do with standard engines driving along the world's public roads.

But we are all free to choose what we want, and I doubt it will make a big difference one way ore another. But I will learn in future, I'm sure

Why the hell not?
Was there a secret ingredient used in the construction of A series engines which makes them behave differently to any other design?




You don't seem to appreciate that the design of most engines from the 1920s onwards was based on the assumption that they would be run on leaded fuel.

< http://www.damninteresting.com/the-ethyl-poisoned-earth >

After tetra-ethyl lead was no longer permitted to be added to fuel, the rate of valve wear will have increased for _every_ engine.

Although we're not in the same boat as those classic car owners whose engines have valve seats cut directly into cast iron cylinder heads, certain changes in settings or adjustments will help ensure longer life for A series engines.

These include ignition timing, carburettor jetting and exhaust valve clearances...

ken

You still fail to prove that chancing the exhaust valve clearence to 0.25 mm will have any significant benefit to a 2cv engine. Just in case that the claim was ever proven the whole world should do so in order to prolong the life of the engine. I have never ignored Citroens specifications since my young days in 1978 and never had any problems getting my engines to be old. Maybe I was just luckly eh

Come on Ken, you should know better than that. No engines are the same.

They were wrong. Instead of being belligerent, try it. The difference is quite significant. As the English say... the proof is in eating the pudding, or some such other phrase.

Please tell how you ''feel'' the significant change?