Low RPM or Speed Tachometer for Tuning - Chevelle Tech
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post #1 of 9 (permalink) Old Aug 9th, 19, 12:29 PM Thread Starter
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Low RPM or Speed Tachometer for Tuning

I have searched the internet many times and I have difficulty finding this for sale but lots of articles about using them for tuning carb. Anyone have a good one that works well for this purpose without spending $100?


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post #2 of 9 (permalink) Old Aug 9th, 19, 12:38 PM
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Re: Low RPM or Speed Tachometer for Tuning

I have an old Sunpro engine analyzer multimeter that has a low RPM tach on it. A co-worker was going to throw it away so I grabbed it. Probably 20 years ago. I used it once or twice when I first got it but prefer to use my timing light tach. I keep it around in case I need to set dwell on something but I haven't touched points in more than a decade. I'm sure you could find one on eBay for cheap.

A vacuum guage is a better tool for idle tuning.



Here you go- $15. Same one I have.

https://offerup.com/item/detail/347000024/

70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

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post #3 of 9 (permalink) Old Aug 9th, 19, 1:48 PM Thread Starter
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Re: Low RPM or Speed Tachometer for Tuning

Quote:
Originally Posted by Tommy the Cat View Post
I have an old Sunpro engine analyzer multimeter that has a low RPM tach on it. A co-worker was going to throw it away so I grabbed it. Probably 20 years ago. I used it once or twice when I first got it but prefer to use my timing light tach. I keep it around in case I need to set dwell on something but I haven't touched points in more than a decade. I'm sure you could find one on eBay for cheap.



A vacuum guage is a better tool for idle tuning.







Here you go- $15. Same one I have.



https://offerup.com/item/detail/347000024/


I have the vacuum gauge. I would see articles that suggest both working together to see slight changes in RPM during adjustment.

Thanks for the help.


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post #4 of 9 (permalink) Old Aug 9th, 19, 2:38 PM
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Re: Low RPM or Speed Tachometer for Tuning

No problem. You certainly can use them together but you'll start noticing that peak vacuum readings coincide with peak idle RPM. The vacuum gauge is more sensitive and my preferred tool as the tach becomes redundant.

Glad I can help.
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70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

76 C20 VortecPro 496 628HP 655 lb/ft TH400 Edge Converter, 4.10 14 bolt
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post #5 of 9 (permalink) Old Aug 9th, 19, 10:18 PM Thread Starter
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Re: Low RPM or Speed Tachometer for Tuning

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Originally Posted by Tommy the Cat View Post
No problem. You certainly can use them together but you'll start noticing that peak vacuum readings coincide with peak idle RPM. The vacuum gauge is more sensitive and my preferred tool as the tach becomes redundant.



Glad I can help.


So what am I looking for? I get to about 15 on vacuum gauge. Then what?


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post #6 of 9 (permalink) Old Aug 9th, 19, 11:28 PM
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Tom
 
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Re: Low RPM or Speed Tachometer for Tuning

You're looking for highest vacuum reading. I can't tell you what that number may be, there's innumerable variables, but if 15 is peak leave it there. Both screws should be the same turns out. Give us some info about your combo if you want tuning tips. As in- what year, make, model, engine, ignition, carb, trans, rear end, cam, compression, intake, exhaust, modifications, intended use. The more you tell us the more we can help.
DwadeCham likes this.

70 Camino...Roller

69 Malibu Stock 307, Reverse Manual TH350, 4,500 Stall Edge Converter, 4.56 Spool 35 Spline 12 Bolt

76 C20 VortecPro 496 628HP 655 lb/ft TH400 Edge Converter, 4.10 14 bolt
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post #7 of 9 (permalink) Old Aug 11th, 19, 11:49 AM Thread Starter
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Re: Low RPM or Speed Tachometer for Tuning

Quote:
Originally Posted by Tommy the Cat View Post
You're looking for highest vacuum reading. I can't tell you what that number may be, there's innumerable variables, but if 15 is peak leave it there. Both screws should be the same turns out. Give us some info about your combo if you want tuning tips. As in- what year, make, model, engine, ignition, carb, trans, rear end, cam, compression, intake, exhaust, modifications, intended use. The more you tell us the more we can help.


I will do my best. Lots of questions there I wish I could answer. I will get to as many as I can but life is pretty hectic right now.


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post #8 of 9 (permalink) Old Aug 11th, 19, 2:14 PM
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Steve
 
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Re: Low RPM or Speed Tachometer for Tuning

If you want a cheap tachometer, these are pretty handy. Good for figuring out pulley ratios too.



They have others, and some are both contact and non-contact.
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post #9 of 9 (permalink) Old Aug 11th, 19, 3:31 PM
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Re: Low RPM or Speed Tachometer for Tuning

A dwell tach or tach & dwell meter is a thing of the past but if your car is a thing of the past you're probably gonna need one.

John
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