DIESEL TO GAS

[TonyL]

I KNOW THIS WONT BE A POPULAR QUESTION BUT WHAT WOULD IT TAKE TO SWITCH MY 6.2 TO GAS MOTOR? I KNOW PEOPLE HAVE GONE THE OTHER WAY WITH THE SWAP BUT I WAS JUST WONDERING IF ANYBODY HAD SOME IDEAS.

THANKS

TONY

[catmandoo]

actually it's easier to go to gas rather than to diesel.the only major things are exhaust manifolds and acc brackets.

[TonyL]

How about the fuel lines and tank, any thought about ignition?

[arveetek]

The pink wire going to the injection pump will plug right into the gas distributor, providing ignition function like normal.

However, why would you want to do this? I mean, why install an engine that requires more maintenance, has a shorter life span, and will cut your fuel mileage in half? Just for comparison, I went from a 9 mpg 305/TH350 with no power to a sweet 20 mpg 6.2L/700R4 with plenty of power. Plus, I no longer have to mess with those nasty carburetors and spark plugs! All I have to do with my 6.2L is change the oil and fuel filters!

Casey

[ropinfool]

I'll throw in my .02 I have been thinking of doing the same thing. I had a 79 Chev w/454 that got 10mpg loaded or empty. I'm getting about 12.5 now (doing 75 on the freeway) and don't have the power to pull any kind of trailer. Now granted I probably have some kind of problem, but I currently don't have the $$ to throw at this truck right now. There are no "local" shops who can look at it, the closest expert is a couple of hours away. Plus at $75/hr things can add up quick. I love my truck, it does ok by itself, around town I'm cruising but get out on the road, it'll peg the speedo on flat ground with no problems, but hit just a little hill, speed comes down and temps go up quick. Just my experience. John

[TonyL]

The reason I am thinking about it is the 6.2 thats in it now leaks oil from every where, coolant, and fuel. It doesn't start well, and to take all the time and money to fix it I could build a 350 that would have twice the power that the diesel would ever had. I have heard of these 300 HP 6.2's which is cool but for the money they spend to get them it is not worth it.(I belive Dr. Lee said his motor was about 6000.00 without a turbo) What i am thinking about buying is a GM crate motor they have a 350 with 330 hp 380ft lbs tourqe for 3300.00 and comes with a warranty. Gas mileage doent matter to me as I live about 1/4 mile from work. But what what does is being able to pass old ladies on the freeway. Any more opinions are welcome as I am still deciding.

Tony

[john8662]

My advice, why take a diesel off the road? I would advertise your truck for sale. Just sell the truck to someone that wants to put the wrench time into it that wants the diesel. Its not hard at all to find a really nice gas truck priced right. Heck, and 80's model gas truck in good shape will cost you what your looking for in that 300hp gasser motor. Its not really worth it to convert over to gas, even for the power. The best idea in my opinion (others may differ) is if you want a gas truck, get a gas truck. If you want a diesel truck, get a diesel truck. I understand the leaks all over. Its a pain in butt to fix. Heck I just picked up an 82 model 6.2 that will make an excellent engine once all the leaks are fixed, but the previous owner pulled and installed a gas motor in its place. So I understand how it happens. Go truck shopping, which is more fun than working on these things..

[Eric Deslauriers]

Save some $$$ and buy the $1300 crate 350. It's 250hp. Add a set of Vortec heads and an intake for another $500, swap in a decent cam for another $100, gaskets for $100 or so, and you have a screaming small block for less than the price of the 330hp or, IMO, overpriced ZZ4.

Car Craft does this all the time and sees up to 400hp. Stop at a used mag place and look through 1-2 years' ago issues.

Don't forget to change your tranny settings for the diesel. At least a new convertor.

Sounds like the right choice for you. My problem is every time I fill my truck, I think of all the other places I could be using the $$$.

I get double the mpg that other 20 year old gas MHs get (10-11 mpg towing), and it's still not enough! ;)

OTOH, now that it's turbo'd, it pulls purty good.

[TonyL]

I have a four speed manual with over drive, not the standard issue four speed with granny 1st gear. The bell housing should bolt right up correct?

[mhagie]

Tony L, I won't try and discourage you from the conversion to gas but in my case I went from 383 gasser to a Avant/Banks 6.5 TD , but then mine is a 80 silverado 4x4 1/2 T.
I did it more to be different than anything else, everybody and their brother has a smallblock , I wanted something different.
As far as to bolting up to block you have nothing to worry about there is only one pattern from the 4.3 V/6 all the way to the 502 crate motor and I would bet the D/Max is still the same pattern.
All I can tell you is to NOT use a 400 smallblock as the base for your engine it has more issues than the diesel you are removing.
If a smallblock is whats desired the 383 is the best pulling one you can make.
Good luck which ever way you choose to go....Merle

[84 Convert]

Been there, done that, and now I'm considering going back the other way! I have the same 4-spOD manual you are talking about, and it bolted right up to my 454. My average mileage with the 454 has been between 10 and 13.5. Which , I think is good for this engine. (On the other hand, what kind of mileage does a 350HP diesel get?) I spent a lot of time getting it tuned to run like it does and if I do swap back I will really miss the power. With an 8000lb trailer , I never had any problems, but then it ate the cam... If I were to do it over, I would probably look for a TPI motor form a Vette or Camaro. They seem to get better than average mileage for a small block. I knew a fellow who had a SB 4WD with a Vette motor who claimed 21mpg on the freeway. Big fish story? Maybe, but it has to be better than my Holley 3310 on a 454. You will also find it hard to get a radiator hose that will fit your diesel radiator and the gas motor. I ended up using Summit racing's custom Stainless hose kit. Yes , Brackets will be a problem, but with a SB you'll have an easier time finding a set than I did.
I do agree with the idea of going truck shopping, but I understand having a truck you don't want to part with as well. Good luck with whatever you do.
Sorry 'bout the long post.

Gregg

[SaintC]

I have an 84 all stock, utility type, flaking white paint, rusted hood, C10....N/A 6.2

It gets about 13 mpg with street and hwy use. It does not burn oil...it leaks just a bit...starts up within 2 seconds....just a real reliable workhorse.

I think I hit 85 mph once, going downhill, with a tailwind. There is just no power anywhere in the powerband. I have to drive in the slow lane when I am on any kind of hill.

But you know what....owning and driving a diesel is really not about that. I do not know what it is. I would not trade this ratty old truck for anything, except a better diesel. I love the sound it makes when driving.

I recon it is the same for Harley, Triumph, BSA, and BMW bike owners. I have known some who have to work on those bikes on a daily basis, and they just love it.

It is a relationship. When your car craps out on you, the junk yard looks good to send it to. When your diesel gives you trouble, you want to make it right. Diesel owners feel differently about their rides than other folks do about theirs.

Even before I joined here, my truck sat in my driveway with an electrical problem for several months. I only had about 1800 invested in it, but I never considered getting rid of it.

Something about diesels.....

If you have lost that something, or maybe never had it, give someone else out there a chance to own a diesel.

It's good karma :D

[britannic]

Originally posted by SaintC:
I have an 84 all stock, utility type, flaking white paint, rusted hood, C10....N/A 6.2

It gets about 13 mpg with street and hwy use. It does not burn oil...it leaks just a bit...starts up within 2 seconds....just a real reliable workhorse.

I think I hit 85 mph once, going downhill, with a tailwind. There is just no power anywhere in the powerband. I have to drive in the slow lane when I am on any kind of hill.

But you know what....owning and driving a diesel is really not about that. I do not know what it is. I would not trade this ratty old truck for anything, except a better diesel. I love the sound it makes when driving.

I recon it is the same for Harley, Triumph, BSA, and BMW bike owners. I have known some who have to work on those bikes on a daily basis, and they just love it.

It is a relationship. When your car craps out on you, the junk yard looks good to send it to. When your diesel gives you trouble, you want to make it right. Diesel owners feel differently about their rides than other folks do about theirs.

Even before I joined here, my truck sat in my driveway with an electrical problem for several months. I only had about 1800 invested in it, but I never considered getting rid of it.

Something about diesels.....

If you have lost that something, or maybe never had it, give someone else out there a chance to own a diesel.

It's good karma :D Plus you always have the option to turbocharge that N/A and pull 85MPH+ whenever you want!

I love driving a sleeper, it really upsets the "go faster crowd" - I've even passed a '99 PSD uphill at 7000' elevation - it was pure joy to see him trying to work out how an old camoflaged truck could do that!

[84 Convert]

Yep, that would be the reason the K2500 still wears a 6.2L Diesel badge! I think I've really surprised a few drivers with that truck! Of course when finances allow, I would really like to go the route of Turboing a 6.2. It sounds like it should run plenty hard for my tastes. Especially when set up like Britannic's. BTW, if you DO swap out the diesel, and wish to replace motor mounts at the same time you will need 6.2 mounts. I bought 454 mounts and found that the bolt pattern didn't match the frame.

Gregg

[britannic]

Originally posted by 84 Convert:
Yep, that would be the reason the K2500 still wears a 6.2L Diesel badge! I think I've really surprised a few drivers with that truck! Of course when finances allow, I would really like to go the route of Turboing a 6.2. It sounds like it should run plenty hard for my tastes. Especially when set up like Britannic's. BTW, if you DO swap out the diesel, and wish to replace motor mounts at the same time you will need 6.2 mounts. I bought 454 mounts and found that the bolt pattern didn't match the frame.

Gregg BTW, I found that 350 poly mount inserts work if you can't find them for 6.2/6.5L.

[panchosteam]

Hi guys:
Over a year later after my truck had major engine problems (1984 6.2 sierra classic pick up)and about 4000 spent on it (now with a 6.5 td} even when i know that i don't have this truck running the way it supossed to run, i will not convert to gas, no wayyy, diesel power feels good when you are driving that diesel truck.


1984 GMC SIERRA CLASSIC PICK UP NOW WITH 6.5 TD AND TURBO MASTER FROM HEATH .

[dieselcrawler]

Ok, I guess I need to say my bit now... I have to agree, having been around diesels all my life, starting with our old '74 Massy Furguson farm tractor, to work van I used to drive, a '93 E-350 7.3L N/A, to my K-30 6.2L play toy, driving a diesel is a frame of mind, maybe even an attitude almost. I just got back from takin' a drive in my truck, there's a little snow here, I was out playin', (and pullin' some lady out of the ditch who lost it on the slick roads) and have found a new joy in just driving now that I have a diesel again... I've had gas jobs, they ran ok, but I'm a compleatly diffrent driver when I'm in a diesel powered truck... I like to hear the roar of the motor as is rattles it's way thru life...
I guess to sum it up, it comes down to this... if you have to ask, yup, I guess you should go with gas... **grin** but to each his own, and a gas motor IS much easier to deal with on a daily basis, as in having it repaired, for most people. But as for me, I'll stick with the ol' DieselCrawler.
Greg

[ueckebes]

just an opinion but i cant really agree with a diesel to gas conversion,unless you are on a budget and the gas engine is dirt cheap or free,if the trucks in good shape and you plan on keeping it a while stay with the diesel . depending on your lifestyle the fuel mileage will soon ofset the extra cost of the rebuild. also be really sure the engine needs rebuilt i have seen engines with blown head gaskets replaced because the owner and in most cases the mechanic believed a blown piston or busted head was the culprit .sometimes the mechanic recomends a replacement just to get more buisness i have experianced this personaly .then their are those who believe a diesel simply dosent belong in a pickup,in some cases i agree but not many.if youre engine isnt knocking or using excessive amounts of oil it probably dosent need replacement,if power and or starting problems is a issue then timing chains or most cases worn injector pumps are probably the culprit.while on the subject of power,a noticeable difference can be made with simple exhaust work fuel ,timeing,settings and aftermarket air filters.the biggest reasons for diesel to gas conversions is probably lack of information on the diesel engine itself.

[84 Convert]

That last sentence sums up the whole reason for the conversion I did, and am now regretting. Eventually I will convert back and install a turbo. But, as has been said before, to each his own.

Gregg

P.S. I'm still amazed at how little mechanics know about the 6.2 most that I run into still think it is a converted gas engine like the 5.7!!

[TonyL]

THANKS FOR THE REPLIES, BUT I WAS HOPING FOR MORE TECHMICAL INFORMATION INSTEAD OF THE MORALITY ISSUES.

TONY

[84 Convert]

No morality issues here, Tony, I do understand what you're planning. I tend to lean toward diesel myself ( I'd like to get my 20 mpg back) but everyone has the freedom to choose their own favorite fuel. As for technical info, I found the swap to be pretty straightforward other than sorting out the wiring (should it stay or should it go). I have a fair amount of wiring background but it still took a week of evenings to get it all sorted and snipped. I reused the radiator and installed a 160 deg. thermostat (180 would be better for heater purposes) have no cooling problems. I had to use custom radiator hoses to make things work together. I mentioned the motor mounts not too many posts back. I lost Cruise but there should be a way to make it work. I built my own bracket for the throttle cable. Had to drain the fuel tanks (not hard with the bed removed,not sure if you leave it on what a guy has to do) to power the HEI, I found a wire that was ignition switched on both start and run positions 12v constant (I think it was brown) I used the hydro-power brake system...had to get the pulley for the gasser installed on the diesel PS pump (if you don't have the proper puller take it to a mechanic shop- I had to). In the end there is NO WAY I could get this thing to pass emissions if I had to get it tested! I do have a non-catalyst sticker so I can be honest when I say I didn't kill a cat in the process, but if I lived in CA or Seattle, I couldn't get away with it until the truck becomes exempt. I you have to be emissions legal, the swap will be much more difficult as I have NO emissions equipment on this truck (might explain the decent mileage)

Anyway good luck and if you have any more specific ?'s post 'em here I'll be checking periodically.

Gregg