Tach with Lil fuel gauge - The 1947 - Present Chevrolet & GMC Truck Message Board Network

plumbers crack · 07-11-2014, 10:19 PM

I found one after searching dozens of yards. I cleaned it up, painted the needles and installed it and the fuel gauge works. Does any one know how many pulses the tach needs to work? I have a few options for signal out put for the cummins but need to know the pulses so I can order the right unit.

The donor truck was a top kick with the 8.3 or something non turbo cat engine.

Just call me Sean · 07-11-2014, 10:46 PM

Now you just need a clock.

plumbers crack · 07-11-2014, 10:51 PM

Yes sir, when I find one worth using.

t_graham11 · 07-11-2014, 10:57 PM

I just went to look at a shortbed frame and can across a cluster just like that I paid the guy cash right there offered him 100$ for it... We got to talking and he is I ended up with an amazing deal, frame, can complete with interior and a new fuel tank and sender all for 300$

That's the beauty about old chevy owners they pass on the generosity to each other

**hatzie** · 07-12-2014, 01:15 PM

Cat Diesel Tach. I believe it runs off a tap in the windings of the alternator so Pulley diameter ratio and the number of poles in the alternator will all enter into it. If you're not driving it with the same Diesel alternator with the same diameter crank pulley you'll have some head scratching to do.

I'd start by setting up a bench experiment to drive the tach with a DC power supply, audio frequency generator, and frequency counter. Then I'd record the frequency to RPM relationship every 500 RPM.
Then I'd attach the frequency counter to a stator tap on the AC side of the diodes in your alternator and observe the frequency vs RPM from the alternator...

Some "Light Reading"

http://www.cumminsforum.com/forum/89...ring-tach.html

http://www.dieselplace.com/forum/63-...lead-tach.html

http://www.turbodieselregister.com/t...for-tach-drive

http://forums.qrz.com/showthread.php...r-driven-Tachs

bdiamond · 07-12-2014, 10:52 PM

Is that km/h? 140 mph speedo would be cool....

Just call me Sean · 07-12-2014, 11:08 PM

Yes kilometers, he's in Canada. I wonder if you could regear the speedometer gears to make it read correctly as MPH.

plumbers crack · 07-13-2014, 12:01 AM

Hatzie, it is all making sense now, guess I have to make a trip to the wreakers where the gauge came from and measure the crank and alt pulley and pull the alt. I have to spend a few hours searching here again too see if anyone has got one of these tach to work.

plumbers crack · 07-13-2014, 12:04 AM

The speedo is in kph. The iroc speedo might be 140 mph.

mr.chevyblack · 07-13-2014, 01:58 AM

all you need is a dakota digital dsl-1 hooks to the altnator and give you your 8 cly pulse out put you would need for a cummins ive done it on a few of my trucks

**hatzie** · 07-13-2014, 08:22 AM

Quote:

Originally Posted by mr.chevyblack

all you need is a dakota digital dsl-1 hooks to the altnator and give you your 8 cly pulse out put you would need for a cummins ive done it on a few of my trucks

For a Gasoline engine tach...
His tach is off a Cat Diesel in a 40-60 series heavy hauler and it's going on his Cummins...

"The donor truck was a top kick with the 8.3 or something non turbo cat engine."

wraprail · 07-13-2014, 11:28 AM

Quote:

Originally Posted by bdiamond

Is that km/h? 140 mph speedo would be cool....

150mph speedo even better

ray_mcavoy · 07-13-2014, 08:56 PM

Many of the GM medium duty trucks with diesel engines used a magnetic pickup mounted near the flywheel for the tachometer signal.

Here's some info from an old GM service bulletin:

If this applies to your tach, the required pulses per revolution will equal the number of teeth on the donor truck's flywheel.

**hatzie** · 07-13-2014, 09:20 PM

The plot thickens...
Bunch of worthwhile info out there in TSB sheets...

plumbers crack · 07-13-2014, 10:32 PM

Quote:

Originally Posted by ray_mcavoy

Many of the GM medium duty trucks with diesel engines used a magnetic pickup mounted near the flywheel for the tachometer signal.

Where did you get that from? That is great info, I must have really good look at the donor truck, see which it is. I should have scratched down the vin.

meatwagon83 · 07-13-2014, 10:53 PM

i would love one of those clusters, guess i need to keep my eyes peeled

motornut · 07-14-2014, 02:18 PM

Quote:

Originally Posted by plumbers crack

I found one after searching dozens of yards. I cleaned it up, painted the needles and installed it and the fuel gauge works. Does any one know how many pulses the tach needs to work? I have a few options for signal out put for the cummins but need to know the pulses so I can order the right unit.

The donor truck was a top kick with the 8.3 or something non turbo cat engine.

looks good,nice score!

**hatzie** · 07-14-2014, 07:06 PM

Quote:

Originally Posted by plumbers crack

Where did you get that from? That is great info, I must have really good look at the donor truck, see which it is. I should have scratched down the vin.

I have a few TSBs from the 70's but haven't had time to scan them. You see them at swapmeets sometimes. I've seen that one before but I don't believe it's in my hardcopies.

plumbers crack · 12-30-2014, 08:54 PM

I had a little time today to play with the tach and hook it up to my 89 gmc plow truck, it worked but at 2000rpm it read 250rpm. At idle it read just off the peg.

I've searched for shops in my area for someone to get me sorted with figuring out the pulses per but came up with nothing. I'm hoping that the Dakota digital box will work with its adjustability.

86c20 · 12-30-2014, 11:26 PM

that cat motor is a 3208. its a v8 so the gas v8 tach will work back and forth. as long as sender is the same. alt or mag or what ever still 8 pluse

nonstop · 12-31-2014, 04:35 AM

I went through this hooking mine up. It picks up off the flywheel teeth. I found a magnetic pick up, drilled a hole in the bellhousing and wired one wire to ground with the other to the tach. It works, but is off since the 454 uses a 168 tooth flywheel and the medium duty trucks use different counts on their flywheels.

07-11-2014, 10:19 PM	#1
plumbers crack Registered User Join Date: Dec 2013 Location: Ont Canada Posts: 65	Tach with Lil fuel gauge I found one after searching dozens of yards. I cleaned it up, painted the needles and installed it and the fuel gauge works. Does any one know how many pulses the tach needs to work? I have a few options for signal out put for the cummins but need to know the pulses so I can order the right unit. The donor truck was a top kick with the 8.3 or something non turbo cat engine. Attached Images __________________ 1990 GMC R35 CC dually, VE cummins, 47RH 2005 Silverado ecsb, 5.3, 2/4 drop, daily work wagon 2000 Yukon xl, 5.3 all stock, wife's truck 2007 Yukon Denali, 6.2 back up truck

07-11-2014, 10:51 PM	#3
plumbers crack Registered User Join Date: Dec 2013 Location: Ont Canada Posts: 65	Re: Tach with Lil fuel gauge Yes sir, when I find one worth using. __________________ 1990 GMC R35 CC dually, VE cummins, 47RH 2005 Silverado ecsb, 5.3, 2/4 drop, daily work wagon 2000 Yukon xl, 5.3 all stock, wife's truck 2007 Yukon Denali, 6.2 back up truck

07-11-2014, 10:57 PM	#4
t_graham11 Registered User Join Date: Apr 2009 Location: Ladysmith BC Posts: 80	Re: Tach with Lil fuel gauge I just went to look at a shortbed frame and can across a cluster just like that I paid the guy cash right there offered him 100$ for it... We got to talking and he is I ended up with an amazing deal, frame, can complete with interior and a new fuel tank and sender all for 300$ That's the beauty about old chevy owners they pass on the generosity to each other

07-12-2014, 01:15 PM	#5
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Tach with Lil fuel gauge Cat Diesel Tach. I believe it runs off a tap in the windings of the alternator so Pulley diameter ratio and the number of poles in the alternator will all enter into it. If you're not driving it with the same Diesel alternator with the same diameter crank pulley you'll have some head scratching to do. I'd start by setting up a bench experiment to drive the tach with a DC power supply, audio frequency generator, and frequency counter. Then I'd record the frequency to RPM relationship every 500 RPM. Then I'd attach the frequency counter to a stator tap on the AC side of the diodes in your alternator and observe the frequency vs RPM from the alternator... Some "Light Reading" http://www.cumminsforum.com/forum/89...ring-tach.html http://www.dieselplace.com/forum/63-...lead-tach.html http://www.turbodieselregister.com/t...for-tach-drive http://forums.qrz.com/showthread.php...r-driven-Tachs __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful. Last edited by hatzie; 07-12-2014 at 04:28 PM.

07-12-2014, 10:52 PM	#6
bdiamond Registered User Join Date: Sep 2007 Location: Wichita Falls, Texas Posts: 459	Re: Tach with Lil fuel gauge Is that km/h? 140 mph speedo would be cool....

07-13-2014, 12:01 AM	#8
plumbers crack Registered User Join Date: Dec 2013 Location: Ont Canada Posts: 65	Re: Tach with Lil fuel gauge Hatzie, it is all making sense now, guess I have to make a trip to the wreakers where the gauge came from and measure the crank and alt pulley and pull the alt. I have to spend a few hours searching here again too see if anyone has got one of these tach to work. __________________ 1990 GMC R35 CC dually, VE cummins, 47RH 2005 Silverado ecsb, 5.3, 2/4 drop, daily work wagon 2000 Yukon xl, 5.3 all stock, wife's truck 2007 Yukon Denali, 6.2 back up truck

07-13-2014, 12:04 AM	#9
plumbers crack Registered User Join Date: Dec 2013 Location: Ont Canada Posts: 65	Re: Tach with Lil fuel gauge The speedo is in kph. The iroc speedo might be 140 mph. __________________ 1990 GMC R35 CC dually, VE cummins, 47RH 2005 Silverado ecsb, 5.3, 2/4 drop, daily work wagon 2000 Yukon xl, 5.3 all stock, wife's truck 2007 Yukon Denali, 6.2 back up truck

07-13-2014, 01:58 AM	#10
mr.chevyblack Registered User Join Date: May 2010 Location: newman lk, washington Posts: 97	Re: Tach with Lil fuel gauge all you need is a dakota digital dsl-1 hooks to the altnator and give you your 8 cly pulse out put you would need for a cummins ive done it on a few of my trucks

07-13-2014, 08:56 PM	#13
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,366	Re: Tach with Lil fuel gauge Many of the GM medium duty trucks with diesel engines used a magnetic pickup mounted near the flywheel for the tachometer signal. Here's some info from an old GM service bulletin: If this applies to your tach, the required pulses per revolution will equal the number of teeth on the donor truck's flywheel.

07-13-2014, 09:20 PM	#14
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,977	Re: Tach with Lil fuel gauge The plot thickens... Bunch of worthwhile info out there in TSB sheets... __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-13-2014, 10:53 PM	#16
meatwagon83 Registered User Join Date: Dec 2012 Location: Preble county ohio Posts: 1,914	Re: Tach with Lil fuel gauge i would love one of those clusters, guess i need to keep my eyes peeled __________________ "DON'T TOUCH THE TRIM!!"-Early Kyler

12-30-2014, 08:54 PM	#19
plumbers crack Registered User Join Date: Dec 2013 Location: Ont Canada Posts: 65	Re: Tach with Lil fuel gauge I had a little time today to play with the tach and hook it up to my 89 gmc plow truck, it worked but at 2000rpm it read 250rpm. At idle it read just off the peg. I've searched for shops in my area for someone to get me sorted with figuring out the pulses per but came up with nothing. I'm hoping that the Dakota digital box will work with its adjustability. __________________ 1990 GMC R35 CC dually, VE cummins, 47RH 2005 Silverado ecsb, 5.3, 2/4 drop, daily work wagon 2000 Yukon xl, 5.3 all stock, wife's truck 2007 Yukon Denali, 6.2 back up truck

12-30-2014, 11:26 PM	#20
86c20 Registered User Join Date: Mar 2012 Location: edgartown mass Posts: 852	Re: Tach with Lil fuel gauge that cat motor is a 3208. its a v8 so the gas v8 tach will work back and forth. as long as sender is the same. alt or mag or what ever still 8 pluse __________________ 1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car

12-31-2014, 04:35 AM	#21
nonstop Registered User Join Date: Dec 2014 Location: Northern California Posts: 422	Re: Tach with Lil fuel gauge I went through this hooking mine up. It picks up off the flywheel teeth. I found a magnetic pick up, drilled a hole in the bellhousing and wired one wire to ground with the other to the tach. It works, but is off since the 454 uses a 168 tooth flywheel and the medium duty trucks use different counts on their flywheels.



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