73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Diesel Engine Discussion => Engine/Drivetrain => Cummins Swaps => Topic started by: wildcatjason on September 12, 2011, 05:38:20 pm
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I think it's cool to see a site that finally appreciates the old square body suburbans. I love the convince but hate the gas mileage. This is my solution. I have attached a picture of the donor 1986 Utilimaster step van this 1990 cummins 4bta came out of. It's rated at 120hp and 305ft/lbs of torque. I put a transmission in it that has a granny 5spd with an overdrive with the idea of raising the rear to a 2.73 ratio putting the granny first very close (its still a little lower then the 700r4 1st) to the overall ratio of the original 700r4 what will feel like a double overdrive since 4th will be 2.73 and 5th will be a 2.05 if I remember correctly.
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your picture didn't work.
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Sorry I can't shrink any much further it says they are to big. I'll see if this will work it is of the donor.
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Use this link to resize and upload, you are putting the location on your local computer...
http://forum.73-87chevytrucks.com/smforum/index.php?topic=6428.0
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Here is the engine before I pulled it out and preformed a total overhaul and here is one after the overhaul on a stand.
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The recipient after the worn out 350 was pulled and put in these cool turn signals. I am going to make a custom grill out of round bar with the block warmer attached.
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I know there is a tilt to the engine because I originally had the 700r4 behind it, but I had some issues with that transmission so I went with something tougher. It is level now. They tilt the cummins to chevy adapter in those stepvans due to engine fitment. The stepvan had a chevy 400 turbo behind this engine. I wanted overdrive. I went to a destroked adapter with a zf5 that leveled out the engine so I can shut the hood. I was going to put a cowl on it.
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you have to make a copy of the image before you resize it. Or if you can't figure that out, upload it to a photo sharing site.
The images you linked are on another site and it won't show up as they require a membership to view it.
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Here is one with the engine level and the hood on, also the rear of the truck.
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Sorry about that. I will see if I can figure it out.
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you have to make a copy of the image before you resize it. Or if you can't figure that out, upload it to a photo sharing site.
The images you linked are on another site and it won't show up as they require a membership to view it.
Thank you for the help. I will contribute. Money is tight right now because my wife recieved a concussion and has been out of work for the past month, but when she is able to go back to work I plan on it. I love these sights that help guys experiment with new things. Keep up the good work! The problem with my picture was that my digital camera was storing pictures as several hundred MBs there was no way to shrink them down under 128kbs. Flickr did it for me. Thanks again!
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Please report when you start driving it, especially the fuel mileage.
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Please report when you start driving it, especially the fuel mileage.
Will do! I got to drive it a little bit with the 700r4 and I could tell the difference in how fast the gas needle would move, but I didn't get to drive it enough to get numbers. I thought the torque converter went out, but it was an adapter bolt that backed out and got in the flexplate, so I bought a 5 speed before I pulled it out and found the problem. I wanted a 5spd to begin with, right now I have to build a transmission crossmember, get a starter, and have a driveshaft made/modified. I should start rollin coal after that.
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Cool ... love seein the burbs! Figuring out a way to get decent mpg and I would drive mine a LOT more :D
Love your pics. Would like to see more detail though. Since you already have a Flicker acct you can just link to the pics there and post bigger images. Somewhere on the Flicker page there will be a link listed. Just copy that then in your post here click on the little insert pic button below the formating line and past in that link.
Did you get your a/c working? Did you fab up that bracket?
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Maybe it's because I'm not a member, but I have not been able to do it. I've tried several times.
My a/c compressor was going out before this swap. It will turn on, but makes a horrible grinding noise. There is a place in montana where you can buy the bracket lots of chevy/ford trucks to the 6bt. It took very little modification to make it work with my ac compressor and it would hit the power steering pump without the vacuum pump. It was an easy fix. www.autoworldmt.com has lots of swap stuff for cummins.
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I would not be surprised if you can squeak 40 mpg at 60 mph out of this rig with the 2.73 rear end and manual transmission. Does your Cummins 4BT use a VE pump? And have you advanced the timing? Advancing the timing can get you a bit better fuel economy.
For better MPG's, consider installing a BHAF (Big Honkin Air Filter) like what I've got on my 1990 Suburban.
(http://img.photobucket.com/albums/v48/rhedahl/P1070640.jpg)
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I think 40 mpg might be a little bit of a pipe dream, but I am hoping for high 20's. Everyone says to advance the timing and I should gassers run better that way and this is my first experience with a diesel so I was a little nervous to screw with the pump to much. Yes it is a ve pump. I did put a 3200 spring in it. I will advance it. Just haven't done it yet. I have the industrial air filter on it from the frito lay truck. It's a least a foot in diameter if not better plus a 3 in exhaust in the back and 4 in the front (plans for a he341 in the future) with a flowmaster muffler (it might be to loud for my taste but I wanted flow).
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I would not be surprised if you can squeak 40 mpg at 60 mph out of this rig with the 2.73 rear end and manual transmission. Does your Cummins 4BT use a VE pump? And have you advanced the timing? Advancing the timing can get you a bit better fuel economy.
For better MPG's, consider installing a BHAF (Big Honkin Air Filter) like what I've got on my 1990 Suburban.
(http://img.photobucket.com/albums/v48/rhedahl/P1070640.jpg)
I see your running the vacuum booster. Does your vacuum pump work pretty well to stop it? Do you prefer that to a hydroboost? If you hit hydroboost hard enough it feels like you could bit your head on the windshield.
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I've also got a 1982 6.2L diesel Suburban with the factory hydroboost brakes so I can comment on both setups.
Yes, the vacuum pump works plenty well to stop it unless I'm trying to stop a trailer loaded with 10k load behind that has no brakes. :o The vacuum pump on the Cummins seems to put out a lot of vacuum so it's plenty adequate for running a vacuum booster. Besides, the 1st generation Dodge's that came with the Cummins ran a vacuum booster as well. However, I will say that the hydroboost stops faster because there is less lag time. I've had sports cars behind my Suburban who had to run off the road to avoid the bumper because those brakes are so quick. The vacuum booster brakes just don't engage as fast.
For your reference, I'm getting 26 mpg with the 1990 Cummins powered Suburban. It's 3/4 ton, 4x4, has a 4" lift, oversize tires, manual transmission and 3.73 rear end.
The 1982 Suburban with the 6.2L and my tweaking gets 30 mpg on the freeway. It's 1/2 ton, 2 wheel drive, 30x10.50 tires, 700R4 and 3.08 rear end.
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I've read about small trucks and Jeeps getting low 30s with a 4bt. If you comb through 4bt swaps you read alot about the gas mileage guys are getting and I can't see this brick getting over the 30 mark, but when I get to drive I will definitely post numbers. I did the math over the OVERALL gear ratio between a 700r4 with a 3.42 and a zf5 and a 2.73. If I ever tow anything relatively heavy it will have to be in third. That will be a 3.88:1 The first four gears of the zf5/2.73 combo would be relatively close to the 700r4/3.42 that I had with a 2.02 5th. I have a 28 in tire. I used a rpm calculator on the internet that said I would turn 1680 @ 70mph. It will be a road trip machine for sure.
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Here is a link to all the photos I took of my swap. Feel free to ask questions. I love gabbin about my truck. http://www.flickr.com/photos/66727529@N03/
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I would not be surprised if you can squeak 40 mpg at 60 mph out of this rig with the 2.73 rear end and manual transmission. Does your Cummins 4BT use a VE pump? And have you advanced the timing? Advancing the timing can get you a bit better fuel economy.
For better MPG's, consider installing a BHAF (Big Honkin Air Filter) like what I've got on my 1990 Suburban.
(http://img.photobucket.com/albums/v48/rhedahl/P1070640.jpg)
Do you have your stock gauges in the truck? When I drove this rig the oil pressure would run high most of the time (60's or greater warmed up) and then suddenly go to 30-40 and fluctuate in between and it would always show over 250 degrees when it warmed up even though you could pop the radiator and stick your finger in it. (New water pump and thermostat) I wonder if I should switch to mechanical gauges. Did you have any problems like that with your 6bt?
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Do you have your stock gauges in the truck? When I drove this rig the oil pressure would run high most of the time (60's or greater warmed up) and then suddenly go to 30-40 and fluctuate in between and it would always show over 250 degrees when it warmed up even though you could pop the radiator and stick your finger in it. (New water pump and thermostat) I wonder if I should switch to mechanical gauges. Did you have any problems like that with your 6bt?
Yes I have stock gauges in the truck. My oil pressure stays pretty much constant at 60. And my engine temperature stays pretty constant at 180 degrees. However, the temperature will climb pretty fast if I'm pulling a 10k load up a 7% grade and try to maintain 65 mph. I don't ever let it go above about 210 degrees when pulling.
I wonder if the 250 degrees is actually half of that, 125 degrees since you said you can stick you finger in the radiator. Using a voltmeter, test the resistance on the engine temperature sensor and see how it compares to a Chevy.
(http://67-72chevytrucks.com/vboard/attachment.php?attachmentid=740335&stc=1&d=1304292910)
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I was also wondering if you have any issues with noise and vibration from the 4BT. How loud is it in the cab compared to the gas engine?
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It's quite abit louder and shakes pretty bad I have a flowmaster to now. I found some factory sound deadner between the carpet and the floor when I've been installing the stick shift. I'm going to spray the heck out of it with lizard skin and have an idea about using a modified motor mount for the rear tranny mount to cut down the shaking. I was also running it without a hood for awhile. Thanks for the advice on the sensor. I think that might do it. I don't have the old chevy sensor anymore because I sold the 350, but my haynes might say something. If anything I could put a reducer in the block and put a chevy sensor in it. There is no way it is running that hot. It feels like hot tub water and at 250 it would be blowing anti freeze. I was afraid the wiring ran through the computer. I do have a youtube video I will get up of my truck running.
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I have tried and tried to post pics and get video up. Here is a link to hear it run. http://youtu.be/F806XvqMrOk
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Yes, I bet the sensors have different resistance values which is throwing your gauge off. However, there are option here.
1. Use a reducer so you can run a chevy sensor
2. Hook a resistor so that resistance matches to a Chevy sensor
4. Put a different face on the temperature gauge
But first off, find the resistance of the sensor when the engine is cold (say 70 degrees) and after the engine is fully warmed up.
Regarding mufflers, here's the muffler you want. This muffler is free flowing and quiet and I don't think you'll find a better price for it. If you're running a 3" exhaust, use a reducer to get the size down.
http://www.ryderfleetproducts.com/ryder/af/ryder/core/content/product/srm/oid/78183/erm/productDetail.do
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Thank you. I just bought this flowmaster, so for I gotta put up with it for now. I will bookmark that for future reference because this suburban has a regency package and it was built for comfort. I would love to keep it that way. I will experiment with the sensor first and probably go with the chevy sensor. I wish I would have kept my old one. It actually may be lying around somewhere, but I doubt it.
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I have tried and tried to post pics and get video up. Here is a link to hear it run. http://youtu.be/F806XvqMrOk
The engine sounds nice and healthy like my Kubota tractor. Thank goodness it has the VE pump on it. It would be significantly louder with the newer style P pump. From what I've seen, the noise and shaking from the 4BT is the biggest complaint of this conversion. There is not much you can do about the shaking but you can do quite a lot with the noise.
If you want to understand more about the science of noise control in a vehicle, read the following:
http://www.sounddeadenershowdown.com/cgi-bin/index.cgi
You can buy the MLV for a better price here:
http://www.soundproofing.org/infopages/flooring.htm
For areas you can't get to with the MLV, mix up some cheap house paint with a bunch of sand and apply a very thick coat of the slurry.
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As far as the shaking I though putting the transmission mount on a hinge to allow it rock back in forth with rubber pads on both sides of the mount pushing it into the crossmember to keep the tranmission from getting to wild. I've got some 1/8" I'll make it out of and reinforce it. I think I want something spray on for most of the undercarriage for the sound. I don't want to start tear up all my carpet. The headliner needs replaced, so I'll buy some lay out stuff then. I think after the hood and firewall I should be good. Thanks again for the advice. It does kind sound like a turbocharged tractor. It will be fun to put around with that 5spd knowing I'm not breaking the bank at the pump.
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I just complete the rear transmission mounts. I decided I wanted to get some of the shake of it so I used these hydraulic mounts out of a late 80s, early 90s taurus.
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I just complete the rear transmission mounts. I decided I wanted to get some of the shake of it so I used these hydraulic mounts out of a late 80s, early 90s taurus.
That looks nice. It'll be interesting to hear back on how well it works.
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Thanks man..I just bought a zf5 clutch line for the slave. I found a hydraulic connector on www.mcmastercarr.com that is good for 4000 psi with no flaring or soldering necessary, so I am going to connect some brake line to my wilwood master cylinder. I have to put in that chevy sensor, make some sheetmetal for the hole in the floor that I cut for the tranny, hook up the grid heater, finish connecting the starter, get a shifter from my dad he's making at work, and get the driveshaft modified. It's coming along.
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Yes, I bet the sensors have different resistance values which is throwing your gauge off. However, there are option here.
1. Use a reducer so you can run a chevy sensor
2. Hook a resistor so that resistance matches to a Chevy sensor
4. Put a different face on the temperature gauge
But first off, find the resistance of the sensor when the engine is cold (say 70 degrees) and after the engine is fully warmed up.
Regarding mufflers, here's the muffler you want. This muffler is free flowing and quiet and I don't think you'll find a better price for it. If you're running a 3" exhaust, use a reducer to get the size down.
http://www.ryderfleetproducts.com/ryder/af/ryder/core/content/product/srm/oid/78183/erm/productDetail.do
I wanted to thank you. I have working gauges that to your suggestion regarding using the chevy gauges to the chevy dash. I should have a working driveshaft by the end of the day, but my injection pump started leaking yesterday and now I have to have it overhauled. Looks like I'm dropping 400 bucks to have it overhauled. It does get up to 210 it you let if idle for a long time (about 30 min)in warm weather (75 degrees) without the fan. Oil pressure is running around 40psi. Thank you again for the suggestion.
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I wanted to thank you. I have working gauges that to your suggestion regarding using the chevy gauges to the chevy dash. I should have a working driveshaft by the end of the day, but my injection pump started leaking yesterday and now I have to have it overhauled. Looks like I'm dropping 400 bucks to have it overhauled. It does get up to 210 it you let if idle for a long time (about 30 min)in warm weather (75 degrees) without the fan. Oil pressure is running around 40psi. Thank you again for the suggestion.
You're welcome. Regarding the leaking injection pump, make sure you're adding some type of lubricant to your fuel. This Ultra Low Sulfur junk that we are having to pay a surcharge for is not friendly to these older injection systems. I've heard of people adding motor oil or transmission oil but I'm using 2-cycle oil since it's made to burn.
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edahall, you may or may not remember when you hooked up your coolant gauge, but I checked the resistance of my wiring leading to the gauge and found a green wire going to it. I hooked this up and ran even though my previous sensor had two wires (yellow and black) which led to the computer for which I removed. The green wire actually went to the coolant fan temp switch from what I read on the wiring schematic. (I had a mechanical fan but that is what haynes says) I know my gauge is still wrong with this one wire chevy sensor I bought. My yellow and black wire are gone because I took out the computer wiring harness. I can find how the computer led to the gauges. The rest is intact. I have my old sensor with the two wires and I know my gauge is off. It will go to 220, but my electric fan with a 190 on, 175 off sensor has been on 3 times since I've driven it. Any help I appreciate I'd like to have an accurate factory gauge. THANKS!
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I can't exactly remember but I'll take a look and report back what I've got.
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I just want to make sure it's accurate. My truck is going clear to 220 at idle and it doesn't make sense that the front of the engine is 30 degrees cooler then the back because the 190 on fan is in the top front before the thermostat. Think of changing the thermostat.
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I checked mine and I'm just running the single green wire just like your setup to the temperature sensor. Have you checked the resistance of the temperature sensor when the engine is fully warmed up? You want to compare that value to what the gauge reports to you.
Also, I'll measure the resistance of my sensor at running temperature and we can compare.
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Well I apprecitate it, but it was the thermostat. I have gone over 200, but one time since I replaced it. It was a new thermostat that I replaced. I hate when new parts are bad!!
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Well I apprecitate it, but it was the thermostat. I have gone over 200, but one time since I replaced it. It was a new thermostat that I replaced. I hate when new parts are bad!!
Good to hear that a good thermostat corrected the issue. What was the situation where it went over 200? The only time the temperature rises on mine is if I'm pulling something too heavy.
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I have no idea. I was just driving and looked down saw that it was at 210. It never did it again. I haven't towed with it at all. I will worry if it does it more frequently. I am excited to see what kinda gas mileage I am going to get. I have been through half tank so far and have 250-300 miles on it. That is a lot of city driving. This is a far cry from what it was doing. The vibrations aren't bad, but it is a noisy thing. I need to work on calming down the cab. I think if I can sound proof just the forward part of the floorboards and under the hood it would make a world of difference. There is a lot noise coming from the shifter boot and transmission hump. Even adding a lubricant to the fuel tank calmed down the engine.
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I have no idea. I was just driving and looked down saw that it was at 210. It never did it again. I haven't towed with it at all. I will worry if it does it more frequently. I am excited to see what kinda gas mileage I am going to get. I have been through half tank so far and have 250-300 miles on it. That is a lot of city driving. This is a far cry from what it was doing. The vibrations aren't bad, but it is a noisy thing. I need to work on calming down the cab. I think if I can sound proof just the forward part of the floorboards and under the hood it would make a world of difference. There is a lot noise coming from the shifter boot and transmission hump. Even adding a lubricant to the fuel tank calmed down the engine.
The elevated temperature may have been due to a trapped bubble in the system that needed some time to purge out.
You'll need to add some type of mass loaded barrier to tame the noise down. There are a number of ways to accomplish this some a lot less costly than others.
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I've been searching it online. I have a few inexpensive ideas. Kinda leaning towards dirt cheap.
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Figured I'd show off a little gas mileage action. This picture is from my iphone. All city miles mind you. There was a 2mpg improvement with tires and alignment.
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It'll be interesting to see what kind of fuel economy it gets on freeway. Have you advanced the timing?
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Yeah. When I had the injection pump rebuilt I went ahead and pushed it toward the head about an eighth of an inch.
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That's not bad mileage for a 3/4 ton suburban around town.
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That's not bad mileage for a 3/4 ton suburban around town.
It's a half ton. Thanks. Long time coming.