Valve clearance

[alfabits]

Just curious what those of you with 1300 Veloce engines set your valve clearance to. I have mine set to the workshop manual standards of .045 mm intake and .5 mm exhaust (about 19 and 21 K) and they make a hell of a racket, especially cold. Seem much better when warm but it takes forever and 15 miles to warm up. I have a friend who races a Giulietta and he says he sets them to about 12 K. Any thoughts on this?

George

[JoeCab]

George,

Running .017" intake and .019" exhaust will quiet things down considerably, while still giving you a safe margin provided you check the clearances occasionally.

[Alfar7]

By reducing clearance you increase duration and the downside is the additional overlap kills off low & mid torque. But if you drive it in the higher rev range who cares....

[Gordon Raymond]

Hi George,
As Alfar7 might agree, part of the noise is the design of the ramps themselves. It would be interesting to see what the clearance is hot, when they quiet down. It might be possible to just tighten them a little without getting to the point where you lose the low and mid range torque. I have never checked this myself, so I don't know if there even is a compromise setting.
As he is the "Cammaster", Alfar7 can suggest a grind that will give you both, better low end torque and high end Hp with a modern design. I have a set suggested by Richard, that I will be using in a restored Ausca single plug 1600.
The design he has suggested uses a much more modern ramp profile, and should offer both long valve train life and improved performance.

[papajam]

Quote:

Originally Posted by Gordon Raymond It would be interesting to see what the clearance is hot, when they quiet down.

[Gordon Raymond]

So, Jim, tightening them by .0025 would probably only slightly reduce George's clatter and, in all likely hood, not affect performance in any noticeable way? Probably not worth the trouble.
With older cam profiles and Alfa grinds, my only experience with these minute adjustments was to get cam timing dead on, cold, with different clearances from one valve to another. As I learned from Richard J. this was a waste of effort, as the timing varied from Alfa's inability to cut each lobe of each cam exactly the same to begin with. I was very impressed with the computer readouts from WebCam on OEM Alfa race cams. With modern technology, the exact variations became apparent. Further, WebCams reprofile was precise, by comparison. This was very educational for me.

[alfabits]

Quote:

Originally Posted by Gordon Raymond So, Jim, tightening them by .0025 would probably only slightly reduce George's clatter and, in all likely hood, not affect performance in any noticeable way? Probably not worth the trouble. With older cam profiles and Alfa grinds, my only experience with these minute adjustments was to get cam timing dead on, cold, with different clearances from one valve to another. As I learned from Richard J. this was a waste of effort, as the timing varied from Alfa's inability to cut each lobe of each cam exactly the same to begin with. I was very impressed with the computer readouts from WebCam on OEM Alfa race cams. With modern technology, the exact variations became apparent. Further, WebCams reprofile was precise, by comparison. This was very educational for me.

[Gordon Raymond]

Hi George,
I'll send you a PM with my E-Mail address, send me yours and I will send you a 15 second video with normal GTA valve noise.

[101/105guy]

Per Gordon's recomendation, I tightened up the clearance on my Duetto's 1600 cams :
10548 intakes are at .016 and 105020320001 exh. cam at .018.

Wonderful results! Quiet when cold and very good torque from low revs.
Thanks !

[Gordon Raymond]

Whew! I'm glad it works! I just sent George a video of my GTA engine running. It does make a noise! Just remember, generally, not always, valve clearances close with use. The tighter they are set, the more often you should check, particularly any that seem like they like to tighten up.
Moreover, as Richard has pointed out, the actual valve timing will change. Heed Richard's advice in all cam related matters. He is very knowledgeable, and I find his experience and wisdom invaluable.

[alfabits]

Quote:

Originally Posted by Gordon Raymond Whew! I'm glad it works! I just sent George a video of my GTA engine running. It does make a noise! Just remember, generally, not always, valve clearances close with use. The tighter they are set, the more often you should check, particularly any that seem like they like to tighten up. Moreover, as Richard has pointed out, the actual valve timing will change. Heed Richard's advice in all cam related matters. He is very knowledgeable, and I find his experience and wisdom invaluable.