12 valve swap.

Discussion in 'Street Build Threads' started by Jake98, Aug 24, 2020.

  1. Jake98

    Jake98 Newbie

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    Hey guys, brand new here but not to gmt400s. I recently bought a 5th gen ss with really low miles to replace my beloved first truck and first build as well. But after driving the Camaro for a month, I really miss my truck but definitely not the fuel economy of a 5.7 TBI with 33s which lead me down the 12 valve rabbit hole I have the cash and already have a mechanic who will do the swap for me my question is how reliable is this swap? I’d be using a donor truck with less than 200k on it but since I don’t know really anything about diesels I wanted to see if a swapped Silverado would be as reliable as a basically brand new Camaro as a daily driver? that I’d take on longish trips(Florida back home to Missouri) 1-2 times and Colorado 1 time a year. Any response is great! Thank you.
     
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  2. Frank Enstein

    Frank Enstein Newbie

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    If the work is done well it should be reliable as a brick. Use a 4L80E transmission with upgrades, change the filters regularly and add quality diesel fuel additive for the low sulphur diesel and run the wheels off it. Only problem is emissions/plates. If you start with a 6.5 diesel truck all the problems go away.
     
  3. 88 one ton

    88 one ton Newbie

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    I have about 2k miles on my 88 c3500 2wd dually 5.9 12 valve conversion.I too am running a 4L80E transmission.Even with 4:10 gears it's still getting 15mpg,my truck has the oddball Dana 70HD-3 rear axle that the aftermarket don't make gearsets for so I'm in the middle of building a 14 bolt rear with 3:73's and should get me close to 20mpg,sure is better than the 8-9 mpg my big block was getting.Trust me you won't be disappointed with the swap. [​IMG]
     
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  4. White96k2500

    White96k2500 I'm Awesome

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    How did you go about hooking the tranny up to the motor and controlling it?
     
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  5. 88 one ton

    88 one ton Newbie

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    Bought the adaptor and adaptor flexplate from Summit $1k.using a eztcu controller but going to swich it out for something else in the future.
     
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  6. White96k2500

    White96k2500 I'm Awesome

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    Thank you for the info! Another question though, was it hard to swap from gas to diesel?
     
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  7. White96k2500

    White96k2500 I'm Awesome

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    Would you happen to have the links? Also what starter did you have to use?
     
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  8. 88 one ton

    88 one ton Newbie

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    It was easy for me,never removed the core support,only pulled the diesel out once to cut some material off the trucks engine mount bracket.There are tons of info on the web for these swaps.

    I have an extra set of new mounts for 88-99 2-4wd for sale if anybody is interested
     
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  9. thegawd

    thegawd I'm Awesome

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    I had to look up what a 12 valve was.... a cummins and probably their most reliable engine? Is this true? I drove a completely supped up and fully deleted 2008 ram with the 6.7, man with the tuner on the dash that truck didnt know that it was not a super car. It was tonnes of fun to drive as a work truck and I was always up for a good challenge that it never let me down. It wasnt mine and wasnt cheap to maintain, it had the extensive body work and had the engine and drivetrain completely rebuilt 5 months after my boss bought it. Someone took a grinder to the head while they were upgrading to the military head bolts that dont stretch.... dumbass. My boss was wondering why he got such a good deal on it...

    Now to have that kind of power and performance in a gmt400. Would be pretty damn cool! I looked up this engine and found a few for sale in my area, they were used in a bunch of different applications besides trucks. What years are best? 94-98?

    Al
     
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  10. 88 one ton

    88 one ton Newbie

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