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yel-mel
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Joined: May 07, 2015
Posts: 427
Location: Tampa Florida
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 Posted: Thu Apr 25, 2024 2:53 pm Post subject: Quick rpm question please |
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Stock 1600 Beetle engine reading rpms at the belt with a touch tachometer and getting 8000 at idle. Is that good ? Im assuming the 8000 on the readout must correspond to 800rpm....not sure how that works
Using an extech 461895 meter |
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bsairhead
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Joined: October 08, 2008
Posts: 3592
Location: viroqua wi.
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| Posted: Thu Apr 25, 2024 3:10 pm Post subject: Re: Quick rpm question please |
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| yel-mel wrote: |
Stock 1600 Beetle engine reading rpms at the belt with a touch tachometer and getting 8000 at idle. Is that good ? Im assuming the 8000 on the readout must correspond to 800rpm....not sure how that works
Using an extech 461895 meter |
You mean old school mechanical tachometer? |
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yel-mel
Samba Member
Joined: May 07, 2015
Posts: 427
Location: Tampa Florida
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| Posted: Thu Apr 25, 2024 3:12 pm Post subject: Re: Quick rpm question please |
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It does have a digital display readout, but the mechanism is a wheel that you hold against the belt or pully.
I dont have a tach in the car....is there a better tool to use ? Trying to dial in my carb
Thanks |
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bsairhead
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Joined: October 08, 2008
Posts: 3592
Location: viroqua wi.
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| Posted: Thu Apr 25, 2024 3:37 pm Post subject: Re: Quick rpm question please |
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| yel-mel wrote: |
It does have a digital display readout, but the mechanism is a wheel that you hold against the belt or pully.
I dont have a tach in the car....is there a better tool to use ? Trying to dial in my carb
Thanks |
You need to use it on the crank pulley nut which you do not have easy access to. A dwell/rpm meter or strobe with tach is what you want. |
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busdaddy
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Joined: February 12, 2004
Posts: 51173
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Thu Apr 25, 2024 4:09 pm Post subject: Re: Quick rpm question please |
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The wheel reads feet per minute, you'll have to use math and determine the lower pulley's circumference.
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 3592
Location: viroqua wi.
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| Posted: Thu Apr 25, 2024 4:10 pm Post subject: Re: Quick rpm question please |
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| bsairhead wrote: |
| yel-mel wrote: |
It does have a digital display readout, but the mechanism is a wheel that you hold against the belt or pully.
I dont have a tach in the car....is there a better tool to use ? Trying to dial in my carb
Thanks |
You need to use it on the crank pulley nut which you do not have easy access to. A dwell/rpm meter or strobe with tach is what you want. |
I ciphered on it and and as long as the wheel on the tach reads 1=1 it should be same same. |
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busdaddy
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Joined: February 12, 2004
Posts: 51173
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Thu Apr 25, 2024 4:13 pm Post subject: Re: Quick rpm question please |
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| bsairhead wrote: |
| ..... as long as the wheel on the tach reads 1=1 it should be same same. |
1:1 what(s)?
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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yel-mel
Samba Member
Joined: May 07, 2015
Posts: 427
Location: Tampa Florida
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| Posted: Thu Apr 25, 2024 4:34 pm Post subject: Re: Quick rpm question please |
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Sorry it's not super clear  . Bottom line what is the best device to test engine idle RPMs & how to use it ,if your bug does not have a tachometer on the dash.
Thanks for your input, the wheel touch tachometer I'm using is a pain in the butt anyway, easier to get something better. |
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busdaddy
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Joined: February 12, 2004
Posts: 51173
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Thu Apr 25, 2024 4:43 pm Post subject: Re: Quick rpm question please |
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A dwell meter often includes a tachometer feature, to adjust your points properly you need a dwell meter.
_________________
Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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bsairhead
Samba Member
Joined: October 08, 2008
Posts: 3592
Location: viroqua wi.
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| Posted: Thu Apr 25, 2024 4:55 pm Post subject: Re: Quick rpm question please |
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| busdaddy wrote: |
| bsairhead wrote: |
| ..... as long as the wheel on the tach reads 1=1 it should be same same. |
1:1 what(s)? |
If it reads on the end, not on the side of the tach or the tach wheel is the same size as the drive wheel it will be right. Sounds like your tach's wheel circumference is 1/10 of the pulleys. That is if your reading 8000 and your only doing 800. |
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kpf
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Joined: March 01, 2017
Posts: 859
Location: California, US
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| Posted: Fri Apr 26, 2024 8:34 am Post subject: Re: Quick rpm question please |
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The Extech 461895 meter has three modes:
- Photo rpm
- Contact rpm
- Surface speed ft/minute or m/minute
Holding the little wheel against the belt can be done with the surface speed setting, but as was mentioned, you'll have to use math (and a ruler) to get from feet per minute to crankshaft rpm.
The best of those three modes to use for an air-cooled VW will be the photo mode. You'll have to add a small piece of reflective white tape to your crankshaft pulley, then point the photo sensor at the face of the spinning pulley. The readout will be in RPM directly (no math involved).
See: https://www.manualslib.com/manual/1384380/Extech-Instruments-461895.html?page=3#manual
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