Dumb question but I did a search LOL

[HYPR]

'72 C20, installing a L83/6L90E removing my 402/TH400 with DNE OD.
What Radiator are you using for this LS swap?
Is anyone else doing a GPS driven Speedo in a Stock Dash? If so which Speedo fits perfectly without looking like a Hot Rod modification (trying to keep it looking stock LOL!)?

[cj847]

I'm sure there is better info in the LS swap page of this forum, but I will start.

You can order a LS Swap radiator from dozens or hundreds of vendors. Just research to make sure it will work for your particular situation. I bought a cheap LS swap radiator, and it cools OK. But, I wrote the company and asked them WHY would ANYONE market an LS swap radiator with an 1 1/2 inlet? I bought it anyway and stretched my old upper hose over it. If it didn't work I would have bought an adapter sleeve. The main thing you need is location and size of inlet and outlet, make sure it has a steam port, and in your case I think the L83's all used electric fans. Don't skimp on fans. It is sometimes difficult to get the info you need. What matters is the volume of air it flows. Dual 12" china fans will not cool like 2 derale 12" fans.

On the cluster. I will recommend that you buy one of the new $1200-$1500 clusters that look original but get data from the computer. I have an LS swap in my shop truck with an original cluster. It is easy enough to adapt the oil pressure and temp gauges. However, a factory 72 gauge is reading red line hot at 200-205 degrees. An LS the thermostat is just opening at 195-200. I have not found anyone making a GPS speedometer for or adaptable to the 67-72. I was even going to order a cheap gps speedo off amazon and adapt my needle and speedo face to it. unfortunately, I have only found 1 270 degree sweep 100 mph gps speedo. It is for a humvee and is sold by Speedhut for about $400. So, new gps speedo + new temp gage + might as well get the matching voltmeter and oil pressure gauge.....you can see my logic. Not worth the effort.

The problem with LS swaps isn't the big stuff. Dropping the engine in, hooking up some headers, etc, is easy. It's the little stuff:

-power steering hoses or adapters
-fuel system again not the big stuff like the tank or the pump, but fuel lines, filters, connections etc
-upper and lower radiator hoses......hope the stock L83 hoses will work with your radiator, if they don't you are in for a frustrating search.
-air conditioning. I found out that a modern chevy compressor will not work with OLD AIR systems AC (not sure about vintage air or others). Something to do with it being variable output or something. What this lead to for me was a new bracket, which resulted in a different serpentine belt and routing, which lead to a new location for my cold air intake, etc, etc

It's been done thousands of times and it is worth the effort just go in with your eyes open and think about how each new part interacts with your old junk.

[Richard]

IDK about the temp gauge information in the previous post? The stock thermostat in my 72 is 195 degrees, same as posted LS temps. No way the stock guage pegs at 5-10 degrees above that. Guessing something going on with his sending unit. The LS sending unit is not compatible with a stock guage.
While I am not a fan, I believe Dakota digital has GPS speedo clusters for the 67-72 trucks. They also have digital to mechanical speedo drives and speedo/tach conversion modules. I have several parts from them for my truck. Will be using a stock type cluster.

[MellowYellow70]

In my 70 LS Turbo swap I used a Classic Dash bezel/plate for my Holley Pro Dash with GPS

[HYPR]

Originally Posted by Richard

IDK about the temp gauge information in the previous post? The stock thermostat in my 72 is 195 degrees, same as posted LS temps. No way the stock guage pegs at 5-10 degrees above that. Guessing something going on with his sending unit. The LS sending unit is not compatible with a stock guage.
While I am not a fan, I believe Dakota digital has GPS speedo clusters for the 67-72 trucks. They also have digital to mechanical speedo drives and speedo/tach conversion modules. I have several parts from them for my truck. Will be using a stock type cluster.

Hi Richard,
I have the Dakota Digital GPS unit driving my VDO Millennium Electronic Speedo in my '56 Chevy and love it. The VDO speed correction programing is complicated as hell and I just got tired of spending an hour dealing with it any time I changed tire sizes etc. The Dakota Digital unit just plan works!
Regarding Gauges for the '72 C20 while I would like to maintain the stock look I also want simplicity and reliability so I am thinking of just swapping out to the Classic Instruments or the New Vintage series and just connect via the interface. At worst case I may need to buy an Interface.

[Joyridin]

For the radiator, it depends on what style pump you are using. My L83 had them both enter/exit on the drivers side. I used a factory style radiator and crossed the lower pipe from the passenger side to the drivers side. This is what the factory did also, but I used a SS pipe instead of their $140 special radiator hose. A double pass LS radiator from a Chevelle would work if you have a different style pump where you can attach both inlet/outlet on the passenger side. I am having no problems with keeping the engine cool. I looked at a double pass with both inlet/outlet on driver side, but it was cost prohibitive. I am using a Cold Case radiator that is 2.5" thick and uses 2 large rows instead of the tradition 3-4 row.

As for the speedo, you can buy a GPS unit that uses your original speedo. It picks up a signal and uses a small electric motor to drive the speedometer. I had one of these in my car for a while. You are stuck on options as the 6l has no speed output. I am currently using a Dakota Digital dash with the BIM adapter. It will sure make your life easy if you want to spend the money on that dash. It uses the OBD port to obtain all the info. I used a Lokar 6l80 shift linkage. It has a metal rod that goes to the column if you want to keep column shift. Worked great.

I don't know if you have swapped any LT engines before, but I just had a major headache. We could not get the engine running correctly as it kept saying there was a vacuum leak of some type. I ran the air intake with a 90 from the TB to a 7" straight, then another 90 downward through the MAF sensor, to another 90 and had the air cleaner under the battery. It looked really nice, but MAF sensor location is super critical on these. I had to change it to run a 90 off the TB with a very long straight through the MAF sensor. I put the air cleaner between the battery and fender with a 75 going into it. After multiple tunes trying to get it running right, this change fixed everything. It started right up and ran fine. All error codes disappeared also. Just a FYI.

[Joyridin]

Originally Posted by cj847

I'm sure there is better info in the LS swap page of this forum, but I will start.

You can order a LS Swap radiator from dozens or hundreds of vendors. Just research to make sure it will work for your particular situation. I bought a cheap LS swap radiator, and it cools OK. But, I wrote the company and asked them WHY would ANYONE market an LS swap radiator with an 1 1/2 inlet? I bought it anyway and stretched my old upper hose over it. If it didn't work I would have bought an adapter sleeve. The main thing you need is location and size of inlet and outlet, make sure it has a steam port, and in your case I think the L83's all used electric fans. Don't skimp on fans. It is sometimes difficult to get the info you need. What matters is the volume of air it flows. Dual 12" china fans will not cool like 2 derale 12" fans.

On the cluster. I will recommend that you buy one of the new $1200-$1500 clusters that look original but get data from the computer. I have an LS swap in my shop truck with an original cluster. It is easy enough to adapt the oil pressure and temp gauges. However, a factory 72 gauge is reading red line hot at 200-205 degrees. An LS the thermostat is just opening at 195-200. I have not found anyone making a GPS speedometer for or adaptable to the 67-72. I was even going to order a cheap gps speedo off amazon and adapt my needle and speedo face to it. unfortunately, I have only found 1 270 degree sweep 100 mph gps speedo. It is for a humvee and is sold by Speedhut for about $400. So, new gps speedo + new temp gage + might as well get the matching voltmeter and oil pressure gauge.....you can see my logic. Not worth the effort.

The problem with LS swaps isn't the big stuff. Dropping the engine in, hooking up some headers, etc, is easy. It's the little stuff:

-power steering hoses or adapters
-fuel system again not the big stuff like the tank or the pump, but fuel lines, filters, connections etc
-upper and lower radiator hoses......hope the stock L83 hoses will work with your radiator, if they don't you are in for a frustrating search.
-air conditioning. I found out that a modern chevy compressor will not work with OLD AIR systems AC (not sure about vintage air or others). Something to do with it being variable output or something. What this lead to for me was a new bracket, which resulted in a different serpentine belt and routing, which lead to a new location for my cold air intake, etc, etc

It's been done thousands of times and it is worth the effort just go in with your eyes open and think about how each new part interacts with your old junk.

The L83 is an LT engine. Lots...and I means LOTS of differences in the engine, hose location, etc. You can use the A/C compressor on an LT engine. There is an very easy way to bypass the variable input and make it turn on/off like a traditional compressor. They changed much of the front of the engine, so if he is using the original serpentine set-up on the L83, more than likely a LS radiator will not work.

Doing a LT has not been done thousands of times. Actually, it is pretty rare due to the tuning needed and all the stupid changes GM made to the engine.

[HYPR]

Originally Posted by Joyridin

The L83 is an LT engine. Lots...and I means LOTS of differences in the engine, hose location, etc. You can use the A/C compressor on an LT engine. There is an very easy way to bypass the variable input and make it turn on/off like a traditional compressor. They changed much of the front of the engine, so if he is using the original serpentine set-up on the L83, more than likely a LS radiator will not work.

Doing a LT has not been done thousands of times. Actually, it is pretty rare due to the tuning needed and all the stupid changes GM made to the engine.

Thanks for all that. Yep I’m learning a lot about the LT vs LS. Some real challenges. I spoke with Chris at PSI assured me they will help me get through this as they have lots of experience with the LT swaps. I am also not looking forward to dealing with the intake plumbing and MAF. Regarding the AC, yep I spoke with Vintage Air and they warned me about the compressor. Some thing about the system getting it’s operating commands from the BCM programming that makes it run full-time and freezing up the system. Good to hear that there is a fix by eliminating the body control module which makes the air condition work that way. I had looked at my Sanden LD 7 in my ‘56 and if needed that would fit if I can get one with either the correct pulley or a 7 rib which will work fine. I will bring that up with PSI disabling the command from the BCM, great advice. Regarding the gauge cluster I have pretty much decided I’m going with New Vintage as they assured me their system will take all the commands from the ECM plus speed control from the 6L90E so no need to go GPS on the Speedo. Regarding the radiator, I had already decided to just go with a traditional driver side inlet and passenger side outlet. I can get an off the shelf unit fabricate a fan shroud for a set of spall 12 inch and use a Dakota Digital fan controller like in my blown ‘56. For the outlet hose it is a simple matter of 3-90’s and two pieces of stainless tubing using shrink clamps. All that is need is brackets to hold it all in place running below the fan shroud. I can build the entire radiator for well under $1500 using a quality US made off the shelf radiator with driver’s side inlet and passenger side outlet plus AT cooler built in. All that is needed is to add the steam port which is no big deal. Plus the advantage is I won’t need to wait up to 12 weeks for it (build time quotes from two different vendors). Thank you guys for all the input and advice.

[Joyridin]

You do not need a steam port. On the thermostat outlet, there is a bleed port. That is the only thing the L83's have unlike the steam port on the LS engines. I plugged the outlet from the thermostat as that originally went to the overflow container and is pressurized. I drilled a small hole inside the housing to connect the port above the thermostat. It works great and you don't need a lot of extra hoses running it to the radiator.

I used a PMW set-up on Derale twin fans. Everything for the radiator was off the shelf and I have about less than $1000 in it. I found the fans new on FB marketplace, so I really have about $750 in the whole deal and the PMW set up doesn't instantly load the alternator. Look at the Autocoolguy.com PMW set-ups. They run totally independent of the computer. I have a Digital Dakota on my car and it is a pain as mine loses the memory when the battery is disconnected and you have to reprogram it. The autocoolguy is totally adjustable.

I bought Speed Engineering headers. They fit perfect on the C-10 if you are going with headers.

[HYPR]

Originally Posted by Joyridin

You do not need a steam port. On the thermostat outlet, there is a bleed port. That is the only thing the L83's have unlike the steam port on the LS engines. I plugged the outlet from the thermostat as that originally went to the overflow container and is pressurized. I drilled a small hole inside the housing to connect the port above the thermostat. It works great and you don't need a lot of extra hoses running it to the radiator.

I used a PMW set-up on Derale twin fans. Everything for the radiator was off the shelf and I have about less than $1000 in it. I found the fans new on FB marketplace, so I really have about $750 in the whole deal and the PMW set up doesn't instantly load the alternator. Look at the Autocoolguy.com PMW set-ups. They run totally independent of the computer. I have a Digital Dakota on my car and it is a pain as mine loses the memory when the battery is disconnected and you have to reprogram it. The autocoolguy is totally adjustable.

I bought Speed Engineering headers. They fit perfect on the C-10 if you are going with headers.

Thank you for the advise on " I plugged the outlet from the thermostat as that originally went to the overflow container and is pressurized. I drilled a small hole inside the housing to connect the port above the thermostat." Could you please send me a photo of what you did? I agree we don't need a ton of extra useless hoses. KISS principal.
Hmmm, If you were having problems with the Dakota Digital PMW Fan controller you likely had it wired incorrectly as I have one on my blown '56 for over two years with no issues at all and I have a battery kill switch in the trunk that kills ALL power period and the Dakota Digital PMW works perfectly. I used to have a Spal controller with my twin 11" Spals when they used to make one. Well it failed and Spal recommended the DD unit.
Since I have experience with Spals and Derale I will likely use one or the other. I use Spals on my radiator and Derale on my Tranny cooler now and both pull a ton of air. So it's a case of stay with what you know.
Yes I factored that I can build the entire set up for about $750-$850 including the cost of metal.

[87chevy.com]

Originally Posted by HYPR

Regarding the AC, yep I spoke with Vintage Air and they warned me about the compressor. Some thing about the system getting it’s operating commands from the BCM programming that makes it run full-time and freezing up the system. Good to hear that there is a fix by eliminating the body control module which makes the air condition work that way.

i really dont see how that they can say that, when you make the L83 compressor work 100% of the time, and its wired like factory c-10 with low pressure switch, how is it going to freeze up? low pressure switch activates and opens circuit....

vintage air system does not communicate with the GM computer from what i remember looking at their instructions on the last install (on a 86 c-10 with l83). Vintage air is completely separate. On the L83 swaps Ive done, ive had no issues with evaporator freezing up with stock compressor and wiring it properly.

clint

[Joyridin]

Originally Posted by HYPR

Thank you for the advise on " I plugged the outlet from the thermostat as that originally went to the overflow container and is pressurized. I drilled a small hole inside the housing to connect the port above the thermostat." Could you please send me a photo of what you did? I agree we don't need a ton of extra useless hoses. KISS principal.
Hmmm, If you were having problems with the Dakota Digital PMW Fan controller you likely had it wired incorrectly as I have one on my blown '56 for over two years with no issues at all and I have a battery kill switch in the trunk that kills ALL power period and the Dakota Digital PMW works perfectly. I used to have a Spal controller with my twin 11" Spals when they used to make one. Well it failed and Spal recommended the DD unit.
Since I have experience with Spals and Derale I will likely use one or the other. I use Spals on my radiator and Derale on my Tranny cooler now and both pull a ton of air. So it's a case of stay with what you know.
Yes I factored that I can build the entire set up for about $750-$850 including the cost of metal.

I can't get a picture without removing the thermostat housing. The thermostat in the L83 is sealed. There is no bypass hole in the thermostat itself like many old cars have, so they use a bypass built into the thermostat housing and send the extra back to the overflow. If you plug the tube outlet, all you need to do is drill a 1/8" hole inside the thermostat housing and connect it with the bypass tube. This allows a small amount of coolant to bypass the thermostat and gets rid of the air pockets.

My Dakota Digital controller is not a PMW set-up. It is programmable for multiple style fans. You literally have to program it and tell it what type of fan, what type of sensor, etc. When you remove power for the Winter or whatever, it wipes the memory and you have to reprogram it. I run a 2 speed Taurus fan on the car. The PMW is obviously much better.

[HYPR]

Originally Posted by 87chevy.com

i really dont see how that they can say that, when you make the L83 compressor work 100% of the time, and its wired like factory c-10 with low pressure switch, how is it going to freeze up? low pressure switch activates and opens circuit....

vintage air system does not communicate with the GM computer from what i remember looking at their instructions on the last install (on a 86 c-10 with l83). Vintage air is completely separate. On the L83 swaps Ive done, ive had no issues with evaporator freezing up with stock compressor and wiring it properly.

clint

Hi Clint,
Thank you for your input on the topic. AC is just one area where I just follow instructions, LOL. I do know that I will want to yank out the huge monstrosity old technology AC system and upgrade it to a new Vintage Air set up. It is just way cleaner. Now regarding their comments that the BCM from the L83 set up not cycling or having the compressor run full time I am sorry all that is way above my pay grade so I will simply defer to people like yourself and PSI as to how to make it all work. To me a compressor should be a compressor driven by a belt and receiving it's command from the system. If on the L83 there is something in the BCM that makes it or controls the function differently it would make sense to me that this would be something that can simply be deactivated so that this compressor simply takes it's on off commands from the new AC system. I would want the AC system to operate independent from the ECM and only function when I say so by turning it on and setting the temp and fan speed and vent location manually. So then the only challenge I can see is hoses which can be made up no problem, Compatibility with the new system dryer/evaporator and switch and what type of refrigerant it needs to use and if that compatible with the new Vintage Air system (which considering when the L83 was introduced I am sure they use the same refrigerant). A condenser is a condenser right? Am I missing something here? (BTW, I do understand that the load from the AC may make the engine see a problem and it may code but isn't that something PSI can make the system ignore in the program?).
I'd love to see a photo of your install as it sounds like other that the tranny, we have the same and even that the 6L80E and 6L90E are not that different other than the strength of the internal components. The 6L90 transmission case is 1-3/8” longer, which provides extra room to house two additional pinion gears (6 total) but functionally for this purpose they are identical so that won't be a factor. My '72 C20 Custom Camper truck being a BB I already have the high clearance tunnel however since I have a TH400 with a DNE OD I will like you did need a new driveshaft, no biggie IMO.

[HYPR]

Originally Posted by Joyridin

I can't get a picture without removing the thermostat housing. The thermostat in the L83 is sealed. There is no bypass hole in the thermostat itself like many old cars have, so they use a bypass built into the thermostat housing and send the extra back to the overflow. If you plug the tube outlet, all you need to do is drill a 1/8" hole inside the thermostat housing and connect it with the bypass tube. This allows a small amount of coolant to bypass the thermostat and gets rid of the air pockets.

My Dakota Digital controller is not a PMW set-up. It is programmable for multiple style fans. You literally have to program it and tell it what type of fan, what type of sensor, etc. When you remove power for the Winter or whatever, it wipes the memory and you have to reprogram it. I run a 2 speed Taurus fan on the car. The PMW is obviously much better.

Regarding the DD PMW, now I understand. Yep, when Spal had theirs it was a third party who built it for them. When mine took a crap of course unlike brake light switches which intentionally break in the ON position it decided to take a dump in the NOPE not going to turn on the fans position causing an immediate over heat (108 degree day in traffic DUH over heating and warping a set of AFR Race heads!). Well calling them they picked up the tab for the DD PMW even though the Spal system was over 10 years old. They agreed it should have been designed to fail closed not open. Oh well welcome to Hot Rodding!
Now regarding the Thermostat, I hate to be dense but I want to be sure I understand you correctly. Looking at the attached photo (my old broken outlet tube housing) drill a hole where the red dot on the top of the housing and connect the hose from the new fitting installed into the housing to the overflow correct? Then plug the outlet tube. Or are you saying remove the Thermostat from the housing and drill a hose inside like the second photo with the Pink dot inside the Thermostat housing by first removing the actual thermostat and drilling the hole here? Why couldn't I just drill a hole in the actual Thermostat as pictured Black dot between the two red lines in the third photo. Wouldn't that work fine?

[87chevy.com]

i don't think that's how the cooling system works on that water pump, plug it and simply use the factory radiator overflow nipple to connect to the over flow tank. that line is more for bleeding the air out of the system through circulation. just don't cap off the heater core circuit, it needs to flow

if you connected that to your overflow tank, it would fill up and spill out... it would be like connecting your upper radiation hose to it...

as far as a/c goes, they sell can bus modules, i use them on my builds to turn the compressor off to simulate factory.
Off with high a/c pressure (330 psi), +60% throttle and rpm 4k+. vintage air only can do a pedal switch... with the l83, you will see full throttle way more than you think.. would recommend looking into setting that up as well.
clint

[HYPR]

Originally Posted by 87chevy.com

i don't think that's how the cooling system works on that water pump, plug it and simply use the factory radiator overflow nipple to connect to the over flow tank. that line is more for bleeding the air out of the system through circulation. just don't cap off the heater core circuit, it needs to flow

if you connected that to your overflow tank, it would fill up and spill out... it would be like connecting your upper radiation hose to it...

Ok Clint, that makes sense so I am back to just simply welding in a bung on the tank just like the aluminum replacement for the donor vehicle and connect it up as intended in the tank below the inlet.

Originally Posted by 87chevy.com

as far as a/c goes, they sell can bus modules, i use them on my builds to turn the compressor off to simulate factory.
Off with high a/c pressure (330 psi), +60% throttle and rpm 4k+. vintage air only can do a pedal switch... with the l83, you will see full throttle way more than you think.. would recommend looking into setting that up as well.
clint

Clint, regarding a Can Bus Module who is they? I would assume PSI may be aware of this?
I am just happy this is something doable with the present Compressor.

[Joyridin]

The second picture is the one. Yes, that acts as an air bleed for the system. The original set-up sent it back to the pressurized overflow tank. I do not have that set-up, so you plug the top (where yours is broken off) and bleed it internally. Once the radiator is full after you have run it for a while and allowed the thermostat to open, you will have no problems.

You can run it back to the radiator if you like, but it is doing the same thing. One of the reason GM ran it to the pressurized overflow tank was due to it being the highest point in the system. Unfortunately, unless you can find a different upper thermostat housing, your radiator sits slightly below or equal with the housing.

[Davidf]

Unfortunatley, I did read all the replies to the OP. But, with my LS swap, I used a standard aluminum radiator meant for the truck with the original SBC. I used the LS hoses, no problem. The upper LS hose needed a bit of force to stretch over the larger upper radiator nipple.

For the stock speedo, I used Dakota Digitals electronic to mechanical speedo drive...it works great and is super accurate. Only occasionally does it briefly glitch and cause the speedo needle to swing wildly.

For the temp sender, I used the original gauge sending unit and drilled out the LS head to accept it.

I used the original truck PS steering hoses on the LS pump...just needed one adapter (readily available).

Let's keep it simple and not over think the solutions.

[HYPR]

Originally Posted by Davidf

Unfortunatley, I did read all the replies to the OP. But, with my LS swap, I used a standard aluminum radiator meant for the truck with the original SBC. I used the LS hoses, no problem. The upper LS hose needed a bit of force to stretch over the larger upper radiator nipple.

For the stock speedo, I used Dakota Digitals electronic to mechanical speedo drive...it works great and is super accurate. Only occasionally does it briefly glitch and cause the speedo needle to swing wildly.

For the temp sender, I used the original gauge sending unit and drilled out the LS head to accept it.

I used the original truck PS steering hoses on the LS pump...just needed one adapter (readily available).

Let's keep it simple and not over think the solutions.

Hey David, Unfortunately what I have found is that the LS and LT installations are very unique to each other and information regarding the LT installations is lagging a bit from some of the vendors and what is worse is some are completely clueless that there are differences. Combine this with the differences between the C10 and C20 especially the Custom Camper and you have a real mess. Thank goodness there are members of the forum who have been there done that so learning on their dime is extremely valuable.
Had not been for this forum I would have gone ahead and just ordered a LS radiator with inlet and outlet on the Passenger side. The LT are both on the Driver side however the install is inlet Driver side and outlet low Passenger side with a cross over plumbing which is no big deal as that is how the 2018 1500's are set up. Easy Peasy to do.

[kev2809]

for the speedo, have you seen the s10 speedo that gets modified into the stock cluster?