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Swopping from gas to diesel?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bigblue82, Jan 14, 2007.

  1. bigblue82

    bigblue82 Registered Member

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    I have an 82 w/ 350 and th350 trans and i am going to swop the motor over to a 6.2 from a gmc truck mid 80s. Anybody know what all needs to change? I know gas lines and tanks but how about radiator, trans and rear end. Any information would be helpful.
     
  2. imiceman44

    imiceman44 1 ton status

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    You will need a radiator from a diesel for the oil cooler unless you want to put an external oil cooler, the 81 and up truck will fit fine so no problem there.
    the th350 you have might be a problem, they never put the 350 behind a diesel so there is no governor for diesel but you can use a th400 torque convertor and you should be OK.
    It's better if you can change to a 700R4 or a th400 and get the diesel version or get the governor and TC from a diesel.
    Other than that, clean the tank and put diesel fuel in it. :D
    You should be fine with the rear end unless you want better mileage then just put bigger tires.
    Diesels don't like high RPMs
     
  3. bigblue82

    bigblue82 Registered Member

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    I have the whole truck that the motor is coming out of so i will take the rad out of it. Its a 2 wheel drive so i will have to track down a 700r4 to fit mine. Any ideas on where i can score one?
     
  4. LovesDunes

    LovesDunes Registered Member

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    Why in the world would you get rid of the 350 for a 6.2?
     
  5. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    How about double the fuel mileage and similar power? That was my reason...plus the 6.2 is awesome offroad.

    Rene
     
  6. LovesDunes

    LovesDunes Registered Member

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    Been there done that. Sure the 6.2 does get spectacular mileage. Compared to the 350. Off road it was ok. On the road to get to the trails it's a piece of crap. In a headwind the 6.2 will actually have trouble moving the rig forward. Towing, the 6.2 is garbage. Or maybe towing an old Camaro was too much to expect. The 350 has more horspower and torque. The inline 6, available in some years, had as much, if not more HP and torque than the 6.2.


    If mileage is the big concern yep it's great. Part replacement is crazy expensive. The injector pump and glow plugs and injectors are very expensive. Adding decent additional power is not going to happen. The head gaskets can't handle addition pressure. Even if you o ring the block and heads. The heads on the 6.2, even the good "J" codes crack between the glow plug hole and the valves. Never seemed to affect power but when rebuilding or just replacing the head gaskets it's an expensive fix. Back in the day, 9 years ago, aftermarket heads were not available. Heads from the yards were all cracked. GM Heads, even at my cost were $1,000 a head.


    The 350 is cheap to maintain, not too expensive to add power, reliable. Yes the mileage is no where near that of the 6.2. But what does that matter if it takes forever to get anyplace. I milked my 6.2 for 6 years. Loved the mileage. My current blazer has a 383 stroker in it. This day and age of fuel injection greatly narrows the gas mileage gap. My 383 has more than 3 times the horsepower and more than twice the amount of torque than my 6.2 did.


    I know lots of people that love their 6.2. Having had one for a long time I don't think it's worth the mileage to do a swap. You don't save all that much in the long run. Diesel in these parts is on average 30 to 40 cents more than gasoline anyways.
     
  7. imiceman44

    imiceman44 1 ton status

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    Well you have a point but what you got was the worst case, not every head cracks, not every engine has trouble, and since so many like you don;t want the 6.2 they are everywhere in junk yards now, and you can get the heads for less than $100 if you are willing to go pick your own in a junk yard.
    I don't think it's the best diesel, but for the price these days, and the ease of having it in a Chevy (bolt in) I think it's a great alternative to high fuel cost.
    Now I would try and find a truck that is already diesel, but if I can't I think it's worth swapping.
    :D
    I will be putting one in my wagoneer when the 360 in it goes, and same with my blazer chalet when the SBC400 goes.
    :wink1:
     
  8. LovesDunes

    LovesDunes Registered Member

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    My 6.2 ran great. For a 6.2. It had 140,000 before I tore it out for a complete rebuild. Rod knock. The 6.2s are all over the junkyards around here. I must have looked at 20 different heads. All had one problem or another. Mostly cracked. I needed my truck for work so all the time I wasted hunting was not good. The cost of the rebuild was stupid expensive. 1000 for heads was just a drop in the bucket. But I thought a fresh rebuild would really liven things up. I really wanted it to work out. The gas mileage was great. I loved that truck. It was quieter, without the rod knock. But it had no more power than it did before. I went so far as to put headers on it. I tried the dual and single plane intakes. Fabed up a really nice looking intake to try and get that "ram air" effect for more top end. But found that it worked best with all the stock components on it.

    I had always wondered about the injector timing since I never had it set with a light so I had the timing set at a shop equiped to do so with their fancy timing light and at its "recommended" factory setting it ran really bad. So I bumped it back up a few degrees after I left. I say "up" but I think as you retard the timing it increases the RPM at idle and makes more power at the top end. It's been awhile.

    On a trails rig my 6.2 was be pretty good. The mechanical injectors are a lot more tolerant to dirt going through them than electronic units. On the trails your not trying to go 65 mph. Just don't get the glow plug controller wet on the back of the drivers side head. They don't like that.

    I sold the truck to a guy that yanked the 6.2 and slipped a Cummins in between the frame rails. WOW. Never thought I would see my Sub smoke the 35" tires.
     
  9. k204dr

    k204dr 1/2 ton status

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    a turbo makes all kinds of difference.
     
  10. LovesDunes

    LovesDunes Registered Member

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  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    You should try combining some agressive gears with the 6.2 and throw a manual tranny in the mix...it will never be a cummin's, but my 6.2/NV4500,4.56 geared combo equals or betters the 350 i had in it before. No the 350 wasn't tired or stock either.

    Rebuilt IP and 8 rebuilt injectors I got done for under $400. Roughly the cost of a new carb.

    The dyno numbers contradict your claims that the sbc puts down more torque than the 6.2. and if the 6.2 spun to 5000 rpm the hp would be comparable too. I still have no idea where GM got their numbers from, but chassis dyno numbers I've found show the real world numbers at the rear wheels are quite a bit higher than advertised (tq anyways...)

    As for the cracks in heads, it is common but also doesn't really affect anything. It's not like they crack through any coolant passages, or even bleed off compression into an adjacent cylinder...

    They are a pretty reliable and inexpensive engine to swap in and run. If you're looking for a tow rig I would use pretty much anything else though. I also wouldn't recomend a small block for towing either though.

    My two cents, obviously your experience and my experience with 6.2's has been different.

    Rene
     
  12. LovesDunes

    LovesDunes Registered Member

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    We definately had different experinces. I was expecting much more from a diesel. Took me a while to realise it's never going to be a towing machine.

    When looking up the numbers for HP and Torque it seems different places have different answers. The stats on this site are different than the numbers on the printed GM brochures. The dyno numbers you were getting were higher than that from GM. Maybe it's the gearing you were running. The numbers I got off the dyno were even lower than that from GM. Probably my lack of gearing and tire size. But then again changing to a lower gear wrecks the gas mileage. As you mentioned the engine does not spin very fast. So if you gear the thing to get up and go, somewhat, you loose the ability to drive long distances unless you go really slow, or keeping the RPMs at the higher end of the tach. The 700R4 I had helped but if it had another gear it would have been great.

    The cracking thing in the heads I always thought was odd. But never seemed to effect the performance or reliability. I could just never bring myself to put a cracked head on an engine.

    If I had had more knowledge back in the day about the 6.2 my experience would have been different I'm sure. I would not have expected so much. For me, the 6.2, in my Sub as a daily driver / trail rig / tow vehicle, in San Diego just did not work out. In Kansas I probably would have loved it. It's all flat there. I don't regret those days of putting around with my 6.2. It just makes me appreciate my PowerStroke that much more.
     

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