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Alfa Pages A forum for help with the Alfasud And Alfa 33 |
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Black Vegetable Alfa Arna
Joined: 08 May 2003 Posts: 9 Location: Helsinki, Finland
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Posted: Fri May 30, 2003 9:19 pm Post subject: Re: standing starts |
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Jas wrote: |
I have 1.7 8v with very lumpy cams, the valves are either open or closed.
Jas |
Don't worry, it's completely normal in your age I'd be more concerned if they weren't either open or closed, for example if they were just closed _________________ It's an Alfa thing, you wouldn't understand it...
Alfa Romeo 33 1.7ie
www.alfaromeo33.tk |
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wille Alfa Arna
Joined: 30 May 2003 Posts: 14 Location: Kerava, Finland
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Posted: Sun Jun 01, 2003 2:48 pm Post subject: |
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I have a '90 1.7ie 8v with Pipercross fillter and "sport" exhaust and I've been surprised how fast it is. For example, my friend and I were driving their Volvo 850 TDi, with 140hp and massive 290Nm torque. When he launched it for several times, it really kicked with all the gears, and I was sure that I have no chance if we'd race. But then we once stopped to lights, I was driving my Alfa and he that Volvo. I could felt my heart bumping a little harder, hand squeezing the steering wheel, and eyes stared to the lights. And when the light turned, HE was the one who had no chance. But what was more surprising happened when I was once driving behind him for about 60kph (38mph). I moved to other lane and changed down to 3rd. I waited when he nailed it, and so did I. We kinda flew side by side, and when he changed to 4th, I managed to get a bit ahead, then changed to 4th and still ahead. But then we had to slow down, because of a turn. I have raced against several other cars, once by 3rd gear with Saab 9000 turbo, and it was a draw. |
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Jas Alfasud
Joined: 24 Apr 2003 Posts: 41 Location: Melbourne, Australia
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Posted: Tue Jun 03, 2003 5:42 am Post subject: cams |
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I think you misunderstand black vege. The cams are lumpy/hot (not standard) because I put them them in there. Short duration cams are good for low speed torque and throttle response, while long duration cams hold the valves open longer for better high speed breathing.
Some duration specs don?t tell you anything about its lobe profile. Two different cams may have identical lift and duration specs, but the lobes on one cam may be ground differently from those on the other. One cam may have more of a peak shaped lobe while the other has a "fatter" lobe. A "V"-shaped lobe will breath differently from a "U"-shaped lobe because it doesn?t hold the valve at its maximum opening as long. Valve float can also be a problem with lobes that change shape abruptly unless valve spring pressure is increased. The profile of the lobes on one cam may also be the same on both the up and down sides of the lobe (which is the norm for most stock and street performance cams) compared to an "asymmetrical" grind (different profiles on each side of the lobe) on the other cam.
ps. I hope you refer to the age of the car |
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