74CHEVC10

iTrader: (1)

I just completed a swap on my 74 chevy truck. has a 1999 lm7 and 2002 4l60e. My stock gauges don't work and i'd like to know how to get em working. I know I need cable-X to use the speedometer but I need to get my gas gauge, oil pressure and temp gauge working. Im running an external fuel pump and stock sender. I also have an aftermarket sunpro tach and want to get that working also. Where do I have to hook the wires up for that?...I already switched it to 4cyl mode.

i r teh noobz

iTrader: (4)

The tach signal comes from the PCM. I think the wire was white, but I don't remember.

Your stock gauge sending units will have to be used to run the gauges. Find out what thread pitch you have, there are tons of adapters out there to make them screw into the LS block.

hackster

Use the stock senders for both cooling and oil pressure. Would be great if you could just pull them off the old motor that you removed, but you could also buy new stock senders for the truck.

I am not sure how you did your swap but all the ones I have done I have been successful in using the wiring diagrams and leaving the stock cluster and gauge wiring and using the old senders in the LS motor. Coolant in backside of passenger head, oil pressure installed in the back of the valley after removing the stock oil pressure sender.

Search ls oil and coolant adapter on Google, you should come up with the adapters to go from metric to whatever thread on your senders.

Not too sure why your fuel gauge doesnt work....maybe start tracing out some wiring?

Sean

ls1nova71

iTrader: (4)

You probably won't be able to find a sender for the temp that will read correctly. There are some that will make it close, but the factory one is the only one that will be as accurate as stock and in order to use it you would need to drill and tap the head as the older senders are too big to fit in an LS head. Ive done it at least 5 times with no problems. The oil pressure gauge on a '74 should be mehcanical, so you can get an adapter for it, or break off the plastic part of the LS sender and drill and tap it for your line. There's pics of both these mods in my build thread of my rusty 71 in my sig. As for the gas gauge, it shouldn't be affected by the swap at all.

74CHEVC10

iTrader: (1)

U guys got any pics of adapters and where i have to put em just so i know exactly what to do...i know where the wire is for the fuel sender but i dont know where to hook it up

lsxRanger94

Fuel gauge issue is usually a bad ground wire to sending unit. You can usually see the sender between the cab and the bed and reach it without pull the tank down if you don't have sausage fingers. LOL wiggle the wire and see if the gauge works. Could be a corroded terminal or a bad sender or the wire came off reinstalling the tank. When you have a bad ground the gauge will read over full and stay there.

74CHEVC10

iTrader: (1)

we actually disconnected it because we took the cab off the frame to do the swap. just don't remember where it goes...its connected at the tank but not the fuel gauge end.

Gray86hatch

iTrader: (83)

I have been using Dakota digital. $800 complete it is a really nice setup. about a 6 hour install.

Tim

lsxRanger94

The wires snap into the back of the cluster(10 pin socket IIRC).

CattleAc

iTrader: (7)

Or...you can do what I did on my 1986 C-30 LQ4 swap...

Source a dash unit from a 1989-1991 Suburban-Blazer-R/V series 10-20-30 C or K pick up...

These have electric speedos from the factory. They are a direct replacement for your dash. They are a one wire hookup from you ECM to make the speedo work...you can hook up the rest of your gauges electrically from your LS engine also.


Cheap, easy, looks factory...

Nilla

You're saying we can use the stock oil pressure sending unit and ect on the 5.3 with the 89-91 dash?

74CHEVC10

iTrader: (1)

Those Dakota digital gauges are too pricey for me but they are kool. As for the suburban gauges I did consider those but I wanted to keep my 100mph speedo.I'm considering upgrading to these(see pic below) sometime down the road. The set is $260 and comes with all the senders

CattleAc

iTrader: (7)

Yeah...I used the "3-wire temp sender" and my temp gauge works fine. And If I remember correctly my LS 6.0L oil sender worked with my factory oil pressure gauge...

The speedo was the sweetest...one wire from the ECM to the dash and I had a dead on accurate speedometer...like I said, easy and cheap.

74CHEVC10

iTrader: (1)

so I took the truck to my buddy and I now have a working fuel gauge and tach...although the tach reads slightly off...I compared it to the reading on my Torque app and its about maybe 200rpms off. It read way off in 4 and 8 cylinder mode but 6 cylinder is closest to the actual reading so I left it there. Its a sunpro tach btw. Im using the app for the temp and speed for now