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  #16 (permalink)  
Old 01-07-2006, 09:17 AM
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The tachometer indicates CRANK rpm. yes it gets its signal from the distributor, which is driven by the cam, which is driven by the crank.

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Old 01-07-2006, 09:56 AM
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multiply rpm's X gear ratio X final drive ratio X tire size ..... youll get the speed you were driving ... heres an online calculator that will do it for you :
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXX
But to check Tach. You Drive 60 M.P.H. / Know the Cir. of your rear tires (Dia. divided by 2 = Rad. X 3.14 = Cir.) [ in Inches! ] Divide 63,360 ( inches in a Mile.) by Cir..! X "Rear end Rato." X 1:1 Trans Hi Gear. = R.P.M. of Crank. { If that number is the same as the tach. is showing; Tach is right!
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Old 01-07-2006, 09:56 AM
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Technically, the distributor driven tach only indicates what the distributor is doing. I can take the distributor out of my engine and rotate it with a drill and make my tach read but my crank isn't moving.
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Old 01-07-2006, 10:12 AM
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Quote:
Originally Posted by onovakind67
Technically, the distributor driven tach only indicates what the distributor is doing. I can take the distributor out of my engine and rotate it with a drill and make my tach read but my crank isn't moving.

your distibutor is POSITIVELY driven!!!!
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Old 01-07-2006, 10:22 AM
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Quote:
Originally Posted by AmericanPackMule
But to check Tach. You Drive 60 M.P.H. / Know the Cir. of your rear tires (Dia. divided by 2 = Rad. X 3.14 = Cir.) [ in Inches! ] Divide 63,360 ( inches in a Mile.) by Cir..! X "Rear end Rato." X 1:1 Trans Hi Gear. = R.P.M. of Crank. { If that number is the same as the tach. is showing; Tach is right!
yea i know the long way to do it

i just didnt feel like typing out all the details ... lol
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  #21 (permalink)  
Old 01-07-2006, 12:02 PM
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Well, I did some research on the subject and I stand corrected............now i feel really dumb..............................
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Old 01-07-2006, 02:05 PM
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Originally Posted by predator carb guru
Well, I did some research on the subject and I stand corrected............now i feel really dumb..............................

NO!!! absolutly NOt so
this is how we learn
my nick name is "slowride66" for a reason ( i guess)
I sometimes get off slower then the rest soon as I know what in doin' i figure a way to catch up

if you came off like 'A know it all' than i'd probally let you wolly in it for a little while

hell I had to look it up !

American Pack Mule is the one at fault here(just kidding)

we all learned something so ... nothing to feel dumb about

I'm Really Slow in the morning!!!

SR66
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  #23 (permalink)  
Old 01-08-2006, 05:42 AM
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R.p.m. @ Tach.

hell I had to look it up !

American Pack Mule is the one at fault here(just kidding)///////////////\\\\\\\\\\

WHERE DID YOU FIND IT?

MY FAULT? No problem! You arn't too slow!
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  #24 (permalink)  
Old 01-08-2006, 06:11 AM
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..66

I see you have a Pontiac I-Con.

I use to race a '58 @ Lions & Orange County 20 years ago; out of Precision Speed Shop. ( Stock Class: H/S ) Best e.t.=14.00 Best M.P.H. 99.99.
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Old 01-09-2006, 06:12 AM
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This is the funniest post I've read yet!! Someone had to much beer this weekend...
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  #26 (permalink)  
Old 01-09-2006, 10:11 AM
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a tach is simply a "spark" counter, the "timer interval" chip on the tach compares the total number of sparks per time interval and puts out an analog signal (0-5V, 4-10ma as ex) to control the pointer movement

you set the dip switches for 4-6-8 cylinders so the chip will divide the total sparks count so that the pointer will show the correct complete firing cycles (per minute on the dial)
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