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07-31-2014, 07:08 PM | #1 |
Registered User
Join Date: Apr 2014
Location: Lafayette, LA.
Posts: 105
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Tach install and RPM's
hey guys i need some help figuring this out, i just pulled a 3 hole cluster out and installed a 7 hole with tach (all factory). and i have taking the truck out twice since the swap
and i cant figure out why my RPM's are reading so high on the tach on the way home i was going 35 MPH and the tach was around 3k in 3rd gear?? specs on the truck are... 350 / th350 stock converter 275/60/15 or 28" diameter i'm not 100% on rear gears but when i used a gear ratio calculator (here) even at 4.11 and 35 MPH it should be 1783 rpm any ideas and thanks for any help Chris
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
07-31-2014, 07:21 PM | #2 |
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Join Date: Aug 2012
Location: Neskowin OR
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Re: Tach install and RPM's
Was the cluster out of a truck with a 6? If so then it's a 6 cylinder tach, and will read high.
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07-31-2014, 07:30 PM | #3 |
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Re: Tach install and RPM's
i got the whole cluster from a another board member who rebuilds them
and it should be a 8 but maybe its not i can pull the tach and check for any markings but are there any numbers to look for?
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
07-31-2014, 07:37 PM | #4 |
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Re: Tach install and RPM's
Doing the math, look slike at 35mph with 4.11's you'd be at 1780ish like you said (not compensating for converter slip), but if the tach is a 6 cyl tach it would read 2310ish. Unless your converter is slipping a lot at 35mph, that doesn't sound right. Not sure what the issue would be if that's the case, the 6 cyl tach was the first thing that came to mind.
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07-31-2014, 07:54 PM | #5 |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Chris,
I got your PM and I will be more than willing to take care of the tach issue for you. I agree that the RPM's you see are high even for a 6 cylinder. You will not see any markings on it that will tell you if it is for a 6 or 8. The original part number comes off when I glass bead the tach tin. I know this tach is for an 8 cylinder. Not sure exactly what the problem is but would like you to send the tach back or even the whole cluster, what ever is easiest for you. I will cover your shipping and get this corrected for you. I sent you a PM also. Thank you for bringing it to my attention. Take care, Tom
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Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
07-31-2014, 08:30 PM | #6 |
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Re: Tach install and RPM's
thanks Tom that more than generous and speaks to the quality of your clusters so thanks again
I'm going to upload a video here is a bit maybe it will help also Tom is there any way to check the tach on the beach i might be able to generate pulsating DC voltage at work or do i need something else?
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
07-31-2014, 08:42 PM | #7 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
I have a tool by Kent Moore that is a tach calibrator and you hook the tach up to it and it will tell you where the tach should read as oppose to where it actually reads. I use this on every tach cluster I sell and it should get the tach very close to right on. Your tach obviously did not like the cal. I also have a NOS tach hear that I use to compare. I use my 72 Cheyenne and a tach harness to check and make sure I don't have needle stick and the RPM looks good. Another thing you can do if possible is find some one that has a timing light that has an RPM read out. Snap On makes one and I know they are very expensive but it will give you an accurate RPM reading. Not sure if that is something you could borrow from someone. If you have a correct baseline, you can turn the calibration screw that is in the back of the tach and dial it in that way. Like I said, I have no problem taking care of this for you but my time has some limitations for the next month. Let me know, Tom
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Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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07-31-2014, 09:03 PM | #8 |
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Re: Tach install and RPM's
here is the vid sorry not the best but you get the idea! lol
started from a stop light and got to around 40MPH and 3rd gear http://youtu.be/dU_nwOYhGNg
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
07-31-2014, 09:17 PM | #9 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
It should depending on your cam between 800 and 1200 roughly. Let me know what you want to do with it and I will take care of this. I really appreciate your patients. By the way, the interior from what I can see of it looks very nice. Not often I get to see one of my clusters after installation Take care, Tom
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Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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07-31-2014, 09:23 PM | #10 |
PROJECT 7DEUCE
Join Date: Dec 2002
Location: GRANTS PASS OR
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Re: Tach install and RPM's
Been awhile since I have been on here but looks like we have another great vendor...
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GO BIG GREEN GO DUCKS MEMBER #6377 72 k-5 daily driver 6'' lift 35'' 350-350-205 slowly getting rust free. Project "7DEUCE" check out my build http://67-72chevytrucks.com/vboard/s...d.php?t=267665 Tim Powell..R.I.P EastSideLowlife..... R.I.P.. |
07-31-2014, 09:28 PM | #11 |
Registered User
Join Date: Apr 2014
Location: Lafayette, LA.
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Re: Tach install and RPM's
thanks Tom the idle seems to be fine around 800 or so
if you think this is just a tach issue i can wait Tom until you let me know when its good for you and i will just send you the tach or is it easier with the whole cluster ? i'm in no rush Tom at our convenience thanks again for this!
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
07-31-2014, 09:30 PM | #12 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
I appreciate the comment. I do not want any un happy customers. Take care, Tom
__________________
Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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07-31-2014, 09:35 PM | #13 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
I will get one ready and need you to PM me your address again. Thanks again for your understanding. Take care, Tom
__________________
Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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07-31-2014, 09:47 PM | #14 |
Registered User
Join Date: Apr 2014
Location: Lafayette, LA.
Posts: 105
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Re: Tach install and RPM's
that sounds great Tom and once again thanks for your help and standing behind
the cluster it speaks volumes to you and your work! pm sent with address
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
08-01-2014, 02:57 PM | #15 |
I am a Referee of life.
Join Date: Jun 2000
Location: Greensboro N.C.
Posts: 13,992
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Re: Tach install and RPM's
That folks is why using BB vendors is preferred over LMC.You get someone who actually knows about these trucks and customer service. Not only that but you can see how the vendor solves problems. And me,McD's can't even get my order right.
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The 47-present Chevrolet and GMC Truck Message Board Network,it's owners,moderators,members,and associates of any type should not be held responsible for my opinion. You can't fix stupid,not even with duct tape. "My appearance is due to the fact that "GOD" does punish you for having too much fun!" Barrett-Jackson has perfected alchemy,they make rust into gold! "You can lead a horse to water but you can't saddle a duck" "Cleverly disguised as a 'Responsible Adult' "Sometimes your Knight in shining armor is just a retard in tinfoil" |
08-16-2014, 02:22 PM | #16 |
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Location: Lafayette, LA.
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Re: Tach install and RPM's
Just wanted to update Tom and pass on that the replacement tach he sent me works 100%
thanks again Tom for all your help and standing behind your clusters great vendor!
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"They Don't write songs about Hondas " 1972 C10 "Ole Red--blood, sweet & beers" USMC 1989-1997 1st Anglico |
08-16-2014, 02:38 PM | #17 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
Have a great weekend, Take care, Tom
__________________
Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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08-16-2014, 05:43 PM | #18 |
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Join Date: Nov 2000
Location: Huntsville Ontario Canada
Posts: 4,051
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Re: Tach install and RPM's
What is involved in adjusting a factory tach. Mine reads 800rpm fast. Its a 8cyl tach
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1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD |
08-16-2014, 05:56 PM | #19 | |
Cluster King
Join Date: Nov 2012
Location: Junction City, OR
Posts: 5,262
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Re: Tach install and RPM's
Quote:
I use a tachometer calibrator made by Kent Moore tools. I also use my 72 Cheyenne with a NOS tach to make sure everything is correct. These tachs may be correct at idle (800 RPM) but be way off at 2000 RPM's. If you are going to adjust it, be careful not to over adjust. It only takes a slight movement to get a big RPM change.
__________________
Contact me on all of your gauge cluster needs. I specialize in restoration, repair and parts sales for 67-72 Chevy and GMC trucks. email me at tbonegarris@yahoo.com I am also a dealer for Counterpart for gauge cluster parts only. Also see my facebook page, CG&C |
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08-16-2014, 06:04 PM | #20 |
Registered User
Join Date: Nov 2000
Location: Huntsville Ontario Canada
Posts: 4,051
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Re: Tach install and RPM's
Its very close at idle. I think the engine is turning 2200 but tach shows 2700-²80ⁿ. I bought a 90 dollar tach from amazon that shows a digital display of rpm I can use to adjust it.
Thanks for the advice I never would have known there tunable.
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1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD |
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