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Thread: 3 GM 6.5's later now I have a Cummins

  1. #21
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    Sep 2006
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    Have you advanced the timing? Advancing the timing improved my fuel economy. I also add 1 oz of 2 cycle oil for every 2 gallons of diesel to keep everything lubricated and improve fuel economy.
    1990 ¾ ton 4x4 Chevy Suburban
    -Cummins Diesel - 12 valve - factory rebuilt
    -6 speed bullet proof manual transmission - NV5600
    -Gear Vendors Overdrive
    -Upgraded Holset HX-35 turbo
    -NP205 iron transfer case
    -3.73 gears

    1982 ½ ton Chevy Suburban
    -6.2L diesel - high nickle crack free 1982 block
    -Stans headers
    -Ported heads
    -Timing gear
    -4 speed automatic
    -3.08 gears
    -30 mpg on freeway

  2. #22
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    Jan 2004
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    I didn't measure the timing with the dial indicator. It's advanced enough to where all you have to do is bump the key to start it. I think 18mph is pretty good for a vehicle this size.
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

  3. #23
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    Quote Originally Posted by computer monkey View Post
    I didn't measure the timing with the dial indicator. It's advanced enough to where all you have to do is bump the key to start it. I think 18mph is pretty good for a vehicle this size.
    The sweet spot is about 1/8 inch past the tick mark.

  4. #24
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    The last time I tried to move the pump, I couldn't by hand. I might tried again with all of the lines lose.

    Not sure what you mean by 1/8 inch past the tick mark?
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

  5. #25
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    Quote Originally Posted by computer monkey View Post
    The last time I tried to move the pump, I couldn't by hand. I might tried again with all of the lines lose.

    Not sure what you mean by 1/8 inch past the tick mark?
    You definitely won't be able to move it by hand. I used a ratchet strap get the pump to budge. Take a look at the following thread.

    How to advance timing 1/8 inch for more power and better fuel economy.
    http://www.youtube.com/watch?v=IZunL...e=channel_page


    Loosen the 3 nuts that hold the pump to the timing case. Loosen the bolt that holds the pump to the rear support bracket. Remove the banjo bolt from the AFC housing. Rotate the pump towards the cylinder head.

    You will need the "s" wrench for the bottom nut. The nut closest to the engine can be gotten with a long 1/4" extension from in front of the fuel filter.

  6. #26
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    youtube video has been removed
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

  7. #27
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  8. #28
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    Thanks Edahall,
    I never have put a mic on it will I first timed the engine so I am not really sure where it is timed in the first place. I know it starts in fifteen degree weather with out heater grid or block heater.

    I'll see if I can play with a little tomorrow or Thursday.
    Thanks again.
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

  9. #29
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    Quote Originally Posted by computer monkey View Post
    Thanks Edahall,
    I never have put a mic on it will I first timed the engine so I am not really sure where it is timed in the first place. I know it starts in fifteen degree weather with out heater grid or block heater.

    I'll see if I can play with a little tomorrow or Thursday.
    Thanks again.
    The timing adjustment I described is by the tick marks as shown by the picture below. You want the two tick marks to be separated by about 1/8". Others have reported an extra 2 mpg by doing this.


  10. #30
    Join Date
    Jan 2004
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    Oklahoma
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    Well I still haven't had time to play with the timing as of yet.
    I wrote up a little history and time line.


    1992 Cummins VE pump engine, 3200 spring, 175hp P-pump industrial injectors (15hp over) dynode 212hp and 520ft/lb at rear wheels. 276k miles plus on engine. Overhaul was done with all std. rod, main and rings. 94 to 02 Dodge inter cool, 94 to 02 Dodge radiator. Hx35w turbo. D-stroke starter ring and GM adapter. Cummins transmission oil cooler mounted under exhaust.


    4L80E transmission with stock guts. First thing I added around 50k miles was B&M shift improver (don't think they even sale this anymore) and a B&M deep dish oil pan. Second was an additional oil cooler. (Suburban was a K1500 6.5 diesel with tow package, all ready had a cooler in front) Without additional cooler tranny ran around 180 to 220 driving around town) Third was a Heath Diesel tranny shift controller (used to increase line pressure). Pretty much ran the tranny shift controller at full setting all the time. I didn't mind the harder shifting. Change transmission fluid about every two years with either Amsoil or Mobil 1.

    Ran this combination till third 6.5 engine broke. Replace with the Cummins at 172k miles. Total mileage on vehcile as of this writing is 198k. With the addition of the Cummins 6bt came the PCS tranny controller. With this I was able to custom tune shift points, lines pressures and torque convertor lockup. I have set up two modes on the controller. One for everyday driving and the other for towing. Both running harder shifts (higher line pressure). The two mode I have higher shift points and lockup points programmed. With the change I now have a B&M tranny cooler with thermostat controlled fan.
    Suburban is a K1500 3/4 ton frame (came with the diesel option). Has 3:42 gears. Vehcile is around 7500lbs in weight. It's a daily driver and trip vehcile. When on trips it's gross weight with small trailer is 11.5k lbs and pulling the toyhauler around 15k lbs. The rear 9.5 semi-float 14 bolt axle was upgrade three months ago with a 2003 2500HD 10.5 full float 14 bolt with disc brakes. Had some problems with the 9.5 overheating in the beginning. Put a Mag-hytec cover and Amsoil heavy duty oil stopped the over heating. Have not had any problems with the 10.5 over heating.

    As of this writing I have had no failures on the vehcile.

    Not much hotrodding is done, mostly pulling.
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

  11. #31
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    Burning Oil is offline http://www.lubedealer.com/pmdcable/home.aspx
    Join Date
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    I did a 6bt in a 96 GMT 400. I was determined to not do a body lift. I did have to lower the front diff 2" and slightly modify the oil pan. Also used the stock hood. My a/c hung off a factory high mount bracket to clear the frame.
    I think you needed the extra hood clearence because of how the a/c in mounted??
    I think I did a write up here on mine a few years ago.
    1993 4x4 1ton 6.5/4l80e runs on WVO.
    1996 1ton 2wd crew cab 6.5/4l80e with db2 IP.
    1996 1ton 4x4 crew cab dually with Cummins diesel
    1970 Chevy 4x4 big block 4 speed.
    1972 Chevelle convertible with 540 CID engine.

    We sell pmd extension cables and the Flight systems PMD or the new Stanadyne PMD with available 7 year warranty.
    Turbo Boost Bolts, engine oil cooler kits and lots of 6.5 turbo diesel parts. Check out the web site
    .

    www.pmdcable.com

  12. #32
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    Jan 2004
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    Oklahoma
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    I used the stock IFS so I was not able to lower the engine any. Plus I mounted the A/C in the factory location make the need to get a cowled hood.
    1998 1500 Suburban 4x4 3:42gears 5.9 Cummins

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