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Old 12-26-2013, 07:51 PM   #1
68c10owner
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diesel to gas conversion

Still searching for another square and found a 82 swb with a diesel. What is involved in converting it to a 350sbc on gas? I know you have to change the tank and fuel lines but is there anything else? I figure I`ll need engine mount and hoses and such but thats the easy part. We dont have to smog diesels here in cali and would be easy to drop a 350 in this thing.
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Old 12-26-2013, 08:13 PM   #2
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Re: diesel to gas conversion

Double check me, but I believe that if you swap a gas engine in to it, it will have to be smogged. And it would have to be a 350 that would have come in it. Might be as interesting if you turbo the 6.2. Just my $0.02
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Old 12-26-2013, 08:19 PM   #3
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Re: diesel to gas conversion

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Double check me, but I believe that if you swap a gas engine in to it, it will have to be smogged. And it would have to be a 350 that would have come in it. Might be as interesting if you turbo the 6.2. Just my $0.02
Here in California we dont have to smog Diesels, yet. As long as I keep it titled as a diesel and they dont want to inspect it I can swap in the 350 with no issues. If they catch on or want to inspect it I would need the smog stuff required for either that year truck or the year of the engine, whichever is newer.
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Old 12-26-2013, 10:08 PM   #4
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Re: diesel to gas conversion

If i were you, I'd keep it diesel and enjoy the MPG!
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Old 12-26-2013, 11:32 PM   #5
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Re: diesel to gas conversion

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If i were you, I'd keep it diesel and enjoy the MPG!
That would be my vote too!! If you want a gas truck,why not just buy a gas one.There must be lots of rust free gas trucks in Cali.
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Old 12-26-2013, 11:37 PM   #6
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Re: diesel to gas conversion

Not buying a truck for mileage. I want a hot rod and don't have any interest in a diesel. There are plenty of rust free trucks but not much to chose from for 73-75 trucks. after 1975 we have to smog every 2 yrs unless its registered as a diesel and then we don't. That's the only reason I'm looking at this diesel truck. I can put a blown 454 or whatever I want and not have to worry about smog.
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Old 12-27-2013, 12:28 AM   #7
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Re: diesel to gas conversion

IIRC the 6.2 is based on a 350 Olds block and the tranny won't bolt up to a sbc without an adaptor. Something else to consider.
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Old 12-27-2013, 12:46 AM   #8
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Re: diesel to gas conversion

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IIRC the 6.2 is based on a 350 Olds block and the tranny won't bolt up to a sbc without an adaptor. Something else to consider.
Engine and transmission will be replaced together and probably a early 12 bolt swapped in there too, maybe a 9". I dont know that I`m going to buy it, planning to try to look at it tomorrow. I have been thinking of any 73-87 truck and do a LS swap. A LS swap could still be smog legal and make plenty of power. Just want to get a nice foundation.
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Old 12-27-2013, 10:02 AM   #9
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Re: diesel to gas conversion

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IIRC the 6.2 is based on a 350 Olds block and the tranny won't bolt up to a sbc without an adaptor. Something else to consider.
the 6.2s and 6.5s use the chevy bolt pattern
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Old 12-27-2013, 10:04 AM   #10
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Re: diesel to gas conversion

you could put a tuned cummins in it just saying. its going to smoke any gas engine you throw in there. the only difference in the diesel trucks im aware is some of the wiring ie glow plugs and 24 volt start and the filler necks on the gas tanks.
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Old 12-27-2013, 10:24 AM   #11
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Re: diesel to gas conversion

The 6.2 shares chevy bolt patterns for trans and engine mounts. If you want to keep the tranny that is in there you will need a gas torque converter. Only the CUCV trucks came with 24v systems. Everything else is a no brainer. The radiator is oversized so it will be fine for any big block you throw in there.
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Old 12-27-2013, 11:50 AM   #12
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Re: diesel to gas conversion

6.2 has nothing to do with Olds engines. You should be able to drop any 73-86 truck SBC into it. You will need to change the converter, your best bet is actulally to swap the trans as the shift points will be at lower RPM. Diesel truck will have a low axle ratio which you will want to swap for a hot rod. You will need a gasser wiring harness. You can flush the tank or swap it.
Quite frankly unlless this is the exact body, color, and trim level you want, or dirt cheap, you'd be better off looking for a gasser, as at the end of the day, the easiest way to convert is to buy a gasser and swap eveything over. Now you've got 2x truck and a lot of time invested.
Cummns conversion is great but way more money.
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Old 12-28-2013, 03:11 AM   #13
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Re: diesel to gas conversion

I can't speak for anything you want to do in CA.

That said I converted a 1986 truck from diesel 6.2 to gasser.

I did not change fuel tank, just did a thorough cleaning of the original fuel system.

I did not swap the wiring harness either. You can clean up the diesel one if you want,(remove glow plug harness and such).

Everything working fine for the last couple years!
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Old 12-28-2013, 03:17 AM   #14
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Re: diesel to gas conversion

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6.2 has nothing to do with Olds engines. You should be able to drop any 73-86 truck SBC into it. You will need to change the converter, your best bet is actulally to swap the trans as the shift points will be at lower RPM. Diesel truck will have a low axle ratio which you will want to swap for a hot rod. You will need a gasser wiring harness. You can flush the tank or swap it.
Quite frankly unlless this is the exact body, color, and trim level you want, or dirt cheap, you'd be better off looking for a gasser, as at the end of the day, the easiest way to convert is to buy a gasser and swap eveything over. Now you've got 2x truck and a lot of time invested.
Cummns conversion is great but way more money.
engine and trans would be swapped together. Its a short fleetside. Most trucks I`ve seen are short step sides lately. 1/2 ton shortbeds are getting tough to find around my area for cheap. Guy is asking $2400 which is right in my budget. Only other thing that cheap in a short fleetside is a 1979 6cyl truck for $1300 but then I have to deal with smog. Good excuse to do a vortec or LS swap though.
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Old 12-30-2013, 10:34 AM   #15
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Re: diesel to gas conversion

If the 82 still has the original 6.2 motor, there will be some demand for it. The original 6.2's were painted red and were unique because the blocks were high in nickel content compared to the newer cheapened down block. These 82 blocks are a good for power mods in the 300-400 hp range.
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Old 12-30-2013, 12:35 PM   #16
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Re: diesel to gas conversion

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If the 82 still has the original 6.2 motor, there will be some demand for it. The original 6.2's were painted red and were unique because the blocks were high in nickel content compared to the newer cheapened down block. These 82 blocks are a good for power mods in the 300-400 hp range.
As far as I know its the original 6.2/700R4. Guy claims 18-22mpg which is about 10mpg more than my 97 gmc currently. I dont know sh*t about diesels so never thought about any performance mods for them. 400hp would be pretty cool though. Do they make much torque? I`m hoping to look at it this week. Guy was out of town till last night.
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Old 12-30-2013, 12:53 PM   #17
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Re: diesel to gas conversion

Bone stock I believe the 6.2 put out 125hp and 250 lb ft of torque. And, yes, 18-22 MPG is very average for those trucks.
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Old 12-30-2013, 01:03 PM   #18
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Re: diesel to gas conversion

sounds pretty gutless, lol. If I pick this truck up I wasn't planning on keeping it diesel but a lot of you saying I should leave it in there have me thinking. I would like some mileage and when I say hot rod I don't nessesarily mean a gas guzzling pig. Just something that makes good power and is fun. Not looking to set any land speed records. Really been thinking a vortec or LS swap in any square I can pick up. It is a fleet side which I prefer and is a 82 and I prever the slant nose years but the main thing is the price. $2400 doesn't get a lot of clean short bed 73-87 trucks around here. Prices are threw the roof lately.
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Old 01-03-2014, 03:52 PM   #19
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Re: diesel to gas conversion

You could move to a free state, then you don't have to worry about all the commiefornia bs!

Just a suggestion.
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Old 01-03-2014, 05:08 PM   #20
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Re: diesel to gas conversion

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Bone stock I believe the 6.2 put out 125hp and 250 lb ft of torque. And, yes, 18-22 MPG is very average for those trucks.
Yes, bone stock they are extremely lethargic However, they respond well to mods. Free up the exhaust / intake and turn up the pump and they'll make some decent power. One thing the 6.2 has over the other diesels is the ability rev up to high rpm's.
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Last edited by Edahall; 01-03-2014 at 05:18 PM.
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Old 01-03-2014, 08:20 PM   #21
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Re: diesel to gas conversion

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The 6.2 shares chevy bolt patterns for trans and engine mounts. If you want to keep the tranny that is in there you will need a gas torque converter. Only the CUCV trucks came with 24v systems. Everything else is a no brainer. The radiator is oversized so it will be fine for any big block you throw in there.
still has 2 batts for start though
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Old 01-03-2014, 08:24 PM   #22
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Re: diesel to gas conversion

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Originally Posted by Edahall View Post
Yes, bone stock they are extremely lethargic However, they respond well to mods. Free up the exhaust / intake and turn up the pump and they'll make some decent power. One thing the 6.2 has over the other diesels is the ability rev up to high rpm's.
adding a turbo does wonders for them i hear also
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Old 01-04-2014, 12:19 PM   #23
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Re: diesel to gas conversion

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still has 2 batts for start though
Yes, in parallel to double amperage. They didn't have reduction starters back then I guess.
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