There is an old saying ....
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,551
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From: Kulpmont PA
There is an old saying ....
A man with a watch knows exactly what time it is. A man with two watches never knows what time it is. A corallary to this is 'a man with a tach knows exactly how fast his engine is turning, and a man with two tachs doesnt'. This applies to speedometers as well, only this time it would be the difference between your speedometer and the radar gun in another vehicle.
ANYWAY, I'm looking for your thoughts. My 30+ year old dwell/tach and my 43+ year old factory tach have a mismatch in RPM. The dwell tach reads about 100RPM higher than the factory tach --- when the dwell tach says I'm at 800RPM, the installed tach says 700RPM.
Does anybody have any insight on the accuracy of the installed tach? I'm inclined to believe it over the Sears dwell tach, but I'm asking in case it's a known fact that they (the installed tach) are notoriously off.
ANYWAY, I'm looking for your thoughts. My 30+ year old dwell/tach and my 43+ year old factory tach have a mismatch in RPM. The dwell tach reads about 100RPM higher than the factory tach --- when the dwell tach says I'm at 800RPM, the installed tach says 700RPM.
Does anybody have any insight on the accuracy of the installed tach? I'm inclined to believe it over the Sears dwell tach, but I'm asking in case it's a known fact that they (the installed tach) are notoriously off.
Team Owner
Joined: Sep 2006
Posts: 31,279
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From: Westminster Maryland
Hi Roy,
One more... "a man with a watch that doesn't work at all knows exactly what time it is twice a day".
Since the tach in the car is mechanical and can be 'calibrated' I'd think that infers that it's not inherently more or less accurate than the dwell tach.
I think it's remarkable that they're both still working and are that close.
I guess I don't know which I'd believe.
Does bringing another dwell tach in to the picture clarify or confuse the issue?
Regards,
Alan
One more... "a man with a watch that doesn't work at all knows exactly what time it is twice a day".
Since the tach in the car is mechanical and can be 'calibrated' I'd think that infers that it's not inherently more or less accurate than the dwell tach.
I think it's remarkable that they're both still working and are that close.
I guess I don't know which I'd believe.
Does bringing another dwell tach in to the picture clarify or confuse the issue?
Regards,
Alan
Thread Starter
Drifting
Joined: Feb 2010
Posts: 1,551
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From: Kulpmont PA
Unless it had a verified calibration, I suspect a third would further confuse the issue. I'm leaning toward the cowards way out and averaging the two.
Le Mans Master
Joined: Jul 2006
Posts: 8,117
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From: charlotte north carolina
i'd trust the electronic dwell/tach meter more than the mechanical/magnetic factory tach. as alan posted, if the factory tach is carefully calibrated, it's probably accurate. but the key word here is 'carefully calibrated'.
Banned Scam/Spammer
Joined: Jul 2007
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From: Oldsmar FL
In today's market a person can purchase a watch (Casio comes to mind) that gets a calibrated signal six times a day from an atomic clock for precise time keeping.
I would agree with jnb5101 and Alan's assessment of a factory tach carefully calibrated as being the most accurate...
I would agree with jnb5101 and Alan's assessment of a factory tach carefully calibrated as being the most accurate...
