55.2-59 Gauges help. Engine and transmission finally set

[Missyblue]

We finally got our 91 350 v8 and 4l80e transmission set in the truck after much fussing and trials with mounts and scrapping the frame brake booster. Finally found engine mounts that worked with minor modifications to keep my original exhaust. And ended up making a mount for the trans mission out of part of the donor vehicle. May part of the donor van forever live on under a much cooler ride haha. So now I am struggling to find info to understand gauges. I had hoped to use my original gauges but my mechanic Helper wants me to upgrade to something more modern. I am doing the wiring with my dad but dont understand the options. I have found a electric to cable box form dakota digital that would help with the speedo but it's like $300. Am I crazy and better off just doing new gauges? Not that they are cheap either but I don't even know that mine work.......advice on brands of gauges or thoughts would be appreciated. Thank you

[dsraven]

the nice thing about the GMC dash is that the gauge holes will likely accept an aftermarket panel gauge or a pod gauge that is removed from the pod/pot that it comes with. I would actually say, by looking, that some of your gauges have been replaced already that way. since the temp and amp gauges have what looks like the stewart warner emblem on them. the tach is also something new to the old dash but I can't make out the emblem, is it putco? for the speedo you can likely also find a panel gauge to fit and get the correct speedo adapter from a local or online speedo repair shop. you may be able to find an electronic gauge to work directly with the new speedo. I would say, personally, to save your money and don't bother having the old speedo fixed because it would mean a speedo repair cost plus an adapter to make the cable driven speedo work with the electronic output from the trans. maybe look at a gps speedo because that way it doesn't matter if you change tire size etc. not sure they work well in nasty weather if it can't get a clear view of a satellite. maybe someone could chime in who has had the experience with those.
lots of guys cut their own dash panels for the GMC dash because they are simply flat sheet. you could even use flat plastic sheet because it is easily worked with hand tools likely found in the home shop. plastic is pretty cheap if you don't have a piece of something laying around. even a piece of wood paneling would suffice for a pattern and to see if you like the look of a new gauge set layout. if that becomes your plan be sure to have your steering wheel of choice in place so you can lay out the gauges in a way that makes them easy to see past the steering wheel. there is also some cool vinyl that could be applied over your "new" dash to make it look like you want without painting etc. I have seen one truck that used the dash cluster from the donor vehicle in his GMC and that enabled him to use the original donor vehicle sending units etc. lots of guys have installed complete dash panels from cars etc, but that is a lot of work plus the front glass needs to come out for access to the spot welds OR the new dash would need to be welded to a stub of the old dash up close to the front glass. never good with the glass in anyway.

https://www.speedhut.com/about-speedometers.html

[dsraven]

do you plan to install a different than stock fuel tank at some point? to get the fuel out of the cab? if so it would be something to consider if changing gauges. the fuel gauge would need to match the new tank sender.
I have thought that an S10 cluster could be made to work in the opening of the GMC dash. I also think the S10 fuel tank from a blazer could also be made to fit behind the rear axle and the filler is on the top left side so it could be made to fill from a fender fill location instead of inside the box. that makes it easier if you plan to actually use the truck to haul a few things or don't like hopping up inside the box to get at the fuel filler.

[dsraven]

blazer fuel tank

https://partsavatar.ca/1985-1993-che...SABEgI96fD_BwE

a how to on building your own gauge cluster. I did not watch it so have no idea if it is any good but I have seen other videos by this guy and he seems to have a good grasp on things. there are several other links in the video by the looks of it. anyway, it may help you fix what you have with some inexpensive parts from the donor if you still have it taking up yard space, lol. if working with plastic like this guys shows, ensure to wear eye protection because plastic shavings are just as sharp as steel.....don't ask.

https://www.ericthecarguy.com/how-to...ument-cluster/

[dsraven]

your gauge panels actually look to be in excellent shape. it would be nice to reuse those with possibly some new gauges tucked in behind the panels. a volt gauge would possibly be a better indicator of what the system is doing. that's just my opinion though. sometimes deals can be had in the marine shops as they use a 12v system as well. you would need to know the pulse count of the trans output. sounds do-able. marine gages are usually just a pod style individual gauge but can be had in a cluster orientation as well.
another gauge upgrade site.
https://www.hotrodhotline.com/updati...-gauge-package

[Missyblue]

Thank you for all the info. I have bought a gm van 22 gallon tank for under the bed already that someone recommended. My 1st choice was to use some of my gauges but only if logical. 2nd best would be to at least keep my dash panels and find gauges if I cant use my gauges. And yes several of mine are aftermarket it seems. The tach gauge though doesnt quite fit so they had it taped in and I dont have the original bezel. 3nd would be to then try something else. I have found complete replacements but they are pricey!! Or cheap on Ebay which makes you wonder quality haha. I'll check out the videos. Thank you. I also do have the van still. Keeping it till I drive my truck off and its "done"

[_Ogre]

missyblue, can you post a couple more pics of the motor & trans in your truck?
that picture of the crossmember looks really low with lots of air above the trans
so low that it looks like you'd be dragging going into a parking lot, maybe even get high centered
you have a lot of free space above your trans, i don't have a good pic to compare

if you compare my x-member, the top of my trans mount is even with the bottom of my frame
you don't want your oil pan and trans pan to be the lowest thing on your truck
i believe my motor is within 1/2" of the stock location, maybe a little further back

[Missyblue]

Originally Posted by _Ogre

missyblue, can you post a couple more pics of the motor & trans in your truck?
that picture of the crossmember looks really low with lots of air above the trans
so low that it looks like you'd be dragging going into a parking lot, maybe even get high centered
you have a lot of free space above your trans, i don't have a good pic to compare

if you compare my x-member, the top of my trans mount is even with the bottom of my frame
you don't want your oil pan and trans pan to be the lowest thing on your truck
i believe my motor is within 1/2" of the stock location, maybe a little further back

So we tried to set it as far back as we could and then we set the engine best we could tell to 3 degrees down at the transmission side. The mounts we finally found to work are meant to be bolt in and flipped but then the engine was too high so we flipped them and mounted flush with the top of my mustang hat. My mustang ii crossmember currently sits 7.5 inches off the ground and my transmissions lowest point is 8.25 inches off the ground. We didnt feel we could raise transmission and engine much as we are getting into my gas pedal linkage area and close to the wings of the transmission tunnel. This is just a large bell housing I think. I could possibly shim and raise things but I bet no more than an inch. My crossmember is a weird design being form the van and i could alter it but currently if I run the original exhaust as.pictured that's going to be my lowest point and bumping area. See if these photos help. I can go back for more and do a better job of showing the close contact at the bell housing

[dsraven]

Good catch ogre.
You could throw a straight edge side to side from bottom of running board to bottom of running board and see what hangs down. Easier and cheaper to fix now than after driveshaft etc has been paid for.

[mick53]

I have Dakota HDX gauges for my 53/3100. They are pricey. I went with a GPS speedo. I have 128 possible gear ratios with changing the ring gear so I wanted the speedo to not be a problem. I was concerned about the loss of signal and accuracy. Dakota told me that their system updates 60 times a second. It also has memory so that if you lose signal it learns and still works. They told me the secret was to have a good antenna. My gauges data log 1/4, 1/8, 0-60, top speed and about everything else but cook dinner. Certainly not for everyone. The GPS is like most other things, you get what you pay for.

[_Ogre]

missyblue: please reconsider your motor height and clearance for the trans x-member
it looks like the trans mount x-member is a couple inches lower than your body
it maybe an optical illusion from the angle of the picture
can you post another picture from the side showing the body relation to x-member?

your mustII x-member can be low and not drag cuz it's between the front wheels
anything between the axles needs to be above the door stepwells and bed running boards
your trans needs to go up a couple inches minimum or it will drag going into driveways

[_Ogre]

Originally Posted by dsraven

You could throw a straight edge side to side from bottom of running board to bottom of running board and see what hangs down.

missyblue, can you show this in a picture?
a straight edge or string line from step to step

[Missyblue]

Originally Posted by _Ogre

missyblue, can you show this in a picture?
a straight edge or string line from step to step

This is the best I could do by myself. Bar is pushed against the body. I have only maybe an incher so before my transmission pushes against my gas pedal assembly and about 2.5 inches before it touches the corners of the transmission tunnel . The trans pan is down a little below the body

[Black_Sheep]

Check out the SpeedHut link that dsraven posted. I have one of their GPS speedos in the '58 and love it.

[dsraven]

missyblue,
you really should consider bumping the engine and trans up some. that is pretty low and you will almost assuredly have issues. not good to tear off a trans pan or worse going over a parking lot entrance or speed bump. the engine end of things could be pretty easy by simply building a spacer off the existing frame part. square tubing would work. the rear would require the cross member to be modded. it is definitely worth the work to do it now rather than later. cheaper too because it could mean another driveshaft mod later if the length changes plus the exhaust work, throttle linkage, rad hoses etc. strive to have nothing lower than the body. you can open the doors and clamp a straight edge across from the steps/rockers from side to side and then the dimension of the trans/crossmember that hangs down below the top of the bar is how much you need to go up with things. it isn't uncommon to have to do a little work to the firewall and/or floor once the engine is where it needs to be. you can trim out a piece of floor and build a sheet metal trans bump that bolts or screws on to the floor with some weather stripping as a seal. a few guys have even chopped a trans bump from a donor car and fit it to their floor/firewall with an added flange to screw it on, and also grabbed the middle piece of carpet/flooring from the donor, so it fits well, then the original carpet/flooring on each side simply flaps over that center piece and looks ok.
you can also use a ratchet strap or 2 to form a piece of sheet over something tubular, like an oxygen bottle or a fence post, in order to fab up a trans tunnel. then screw it to the original center part of the floor that is removeable, if that is a big enough mod to fit the engine/trans combo to where it needs to be. start by removing that panel and jacking the engine/trans up.

[dsraven]

looking at the trans crossmember you could space it up with some square tubing as well.
your throttle pedal could be replaced with the cable operated one from the donor. less likely to have throttle changes with engine load as well because it would be a flexible link between the body and the engine, as the engine moves from changes in load. the pedal assy should simply bolt on to the firewall then a hole for the cable wherever it needs to go.
just a thought.

[dsraven]

looking at the trans crossmember you could space it up with some square tubing as well.
your throttle pedal could be replaced with the cable operated one from the donor. less likely to have throttle changes with engine load as well because it would be a flexible link between the body and the engine, as the engine moves from changes in load. the pedal assy should simply bolt on to the firewall then a hole for the cable wherever it needs to go.
just a thought.

[dsraven]

http://67-72chevytrucks.com/vboard/s...d.php?t=620269
you can form a tunnel from cardboard as a pattern. round corners are easier to get flooring to fit smoothly.

[dsraven]

https://www.ecklers.com/1967-1972-ch...-455804-1.html

maybe something like this could be made to work if required or a center panel from another truck that screws to a flat floor. flooring would be easier when done because you could source a chunk from the donor, and it bolts on to a basically flat floor, except the rear part that also could be made to fit with another hand made filler panel.

[dsraven]

if you use square tubing for spacers you can also move the whole unit a bit forward if required by simply offsetting the holes in the square tubing. drill holes with the spacing you have currently on one side of the tubing, then use welded in bolts in those holes to mount the tubing to the frame, or bolts welded to some flat bar, with the same spacing as the holes, that can be fished into the tubing. then drill holes where the cross member and engine mounts need to be in order to clear the firewall etc.

[Missyblue]

Originally Posted by dsraven

https://www.ecklers.com/1967-1972-ch...-455804-1.html

maybe something like this could be made to work if required or a center panel from another truck that screws to a flat floor. flooring would be easier when done because you could source a chunk from the donor, and it bolts on to a basically flat floor, except the rear part that also could be made to fit with another hand made filler panel.

Thank you for the insight. So my tunnel is already a fairly large hump it's the sides that are the problem and a different humo wouldn't change that I dont think as they are the cab body . I already am so far forward that I will have to use an electric fan because of where my radiator mounts. But might have more wiggle room. The pedal option would be helpful and awesome thanks for the idea. I'll have to discuss with the guys and see what they think I should do. If I did use tubing what thickness would you recommend? My trans mount is 3/16 the engine mounts are 1/4

[_Ogre]

first off, these trucks were designed with V8 and automatic transmissions in mind
your truck has the 4 speed trans cover with the big hump in it, you have room to go up 3 or 4 full inches
if you look at this pic, you see the notch in the x-member above and behind the trans?
that is for the driveshaft

[_Ogre]

now compare my trans x-member with your trans x-member
my trans mount goes on top of that piece of angle iron
the top of my rubber trans mount is a little above the bottom of my frame

now look at your trans x-member and mount: the straight edge is 4 inches under the frame

it would be a lot easier to move your motor and trans up 3 or 4 inches, than to
1) get high centered in every gas station and need to be towed off
2) replace the trans pan and possibly the valve body or
3) worse yet, tear a hole in the oil pan and ruin your motor
it will be a lot easier to redo your gas pedal linkage than any of the above

[dsraven]

yep, I was thinking the same. you can't use the original mounts, because the cross member for them is likely gone, but the truck was made for a small block so it will fit. you may need a shorter water pump or whatever, but it will fit without a firewall modification. the original mounts were bolted to the front of the engine.

here is a pic for reference to height. scroll down in the thread to see it, post 7

http://67-72chevytrucks.com/vboard/s...d.php?t=245358

[_Ogre]

truk runs a genII 350 SBC with long water pump
as far as i know the motor is in the stock location
it still had the old front motor mounts in it when i bought it