1978 K20 Project with No Name

[rustybottoms88]

I was not sure where to put this build. It will see some offroad use but nothing extreme. Its primary use will be farm duties and tow rig. I sold my 4 door SWB 03' 2500HD Silverado and wanted to down size to something old school. I loved my 03' because it was comfortable and pulled good for a gas rig, it had the 6.0L. So I started looking for something fairly solid, that had a decent interior and it could be running or not because I had a 6.0 LS swap in mind eventually.
With the help of some friends(they are always willing to help spend money) we found alot of prospects but I settled on this 1978/82 K20. Story on it was that back in the mid 90's a P.O. swapped a 82' cab and front clip onto a 78" frame. Its received a paint job somewhere along the way but now the clear coat is peeling. The guy I bought it from ran a stump or post down the passenger side door and bed side and attempted to repair it. The owner advertised it as the 350 engine being junk and it is a 400Turbo and NP203. It came with LS swap motor mounts and cab corner patch panels. The owner had recovered the seat.

 

[350TacoZilla]

Looks like a nice starting point, what's the overall plan on drive train? I know you had said 6.0 swap but planning to keep the TH400\NP203 setup or swap to a more modern OD trans? If keeping the 203 make sure it has a part-time kit in it before running it much with lockouts. Guessing it has 10bolt\14 bolt setup in it for axles so while the front is meh its not a big deal for a general use truck as long as tire's are kept to reasonable diameter.

 

[rustybottoms88]

Looks like a nice starting point, what's the overall plan on drive train? I know you had said 6.0 swap but planning to keep the TH400\NP203 setup or swap to a more modern OD trans? If keeping the 203 make sure it has a part-time kit in it before running it much with lockouts. Guessing it has 10bolt\14 bolt setup in it for axles so while the front is meh its not a big deal for a general use truck as long as tire's are kept to reasonable diameter.

The overall powertrain plan is pretty fluid at this point, it will really depend on what drivetrain combo the donor vehicle will have but at the moment I plan to use the TH400 if it is good and as you mentioned a part time kit in the NP203. Ultimately a later model transmission with overdrive would be nice as this thing could see some long distance trips. Since you mentioned axles do you know if the later model chevy trucks with rear disc brakes have a similar WMS to this truck?

 

[350TacoZilla]

It's a bit wider than the rear but closer to front.
Your axles are something like 69" front and 67" rear. Newer disc 10.5aam is 68.5"

 

[rustybottoms88]

So my dad and I went to Mo. and brought this thing home Saturday. I tinkered with it that night and as the owner had mentioned the engine was indeed locked up. So I began by taking the starter off thinking it might be hung up, this required removing the passenger side header. I found that all of the spark plugs had been removed and there was no oil in the pan. I found some pieces of grass and leaves the deeper I began to dig into things. I also noticed one of the head lights had what looked like pond water in it. All bare metal had some light rust like it has been wet.....you see where this is going. Then I found what looked like pond silt in odd places. Like the broken windshield washer bottle and the torque converter cover.

Anyway I messaged the P.O. and asked why there was no oil in the engine. He told me when he was driving it around in a field that is locked up and so he drained the oil to look for chunks but found none except for some metal flake. Again remember that I bought this knowing the engine was "junk" or seized so this is all fine but the appearance of the truck doing a nose dive into a pond was beginning to look probable. Anyway that's all water under the bridge as they say so I poured ATF down the cylinders and over filled the oil pan so the crank bearings would be covered in oil.
Sunday afternoon I put a crow bar on the fly will teeth and managed to get the engine alitte loose working the flywheel back and forth. After a while I became in patient and got out a special tool.

This got things moving pretty quickly and I rotated the engine about 4 times. Then I tested the starter on the bench. It was stuck as well so I freed it up with a screw driver and PB blaster. So I draiend some of the oil since I had over filled it and installed the starter and bam it whorled the engine over pretty good. The engine did have a gallop to it but no banging or clanging sounds. I proceeded to compression test the cylinders.

I could not test #5 and 7 because of the drivers side header being in the way. I was kind of expecting #6 and 8 to be down alittle because I had the valve cover off on that side on Saturday and when I wacked the spring side of the rockers with a plastic mallet those two seemed stiff and/or stuck. They loosed abit at my wacking. So as a friend of mine mentioned the valves could be bent or it just maybe they are rusty and sticky. Time will tell. This evening I am going to put in spark plugs and connect the spark plug wires. I have tested the HEI and it is putting out spark, lets just hope it is timed correctly. With alittle luck and some chainsaw gas it may start. If so I may drive it with this junky 350 for abit while I wait for the right 6.0 LS donor to appear.

 

[350TacoZilla]

Cool deal but if it took a dive into pond you might want to flush trans and such before firing engine and pumping sand through trans if water got up to dipstick level.

Can't go wrong with a running sbc of it's already in there lol. 6.0 donors are becoming cheaper and easier to find now but I wouldn't turn down a 5.3 if you find one for good price, either one will out perform a tired old 350 and 5.3 might return better mpg.

 

[rustybottoms88]

Cool deal but if it took a dive into pond you might want to flush trans and such before firing engine and pumping sand through trans if water got up to dipstick level.

Can't go wrong with a running sbc of it's already in there lol. 6.0 donors are becoming cheaper and easier to find now but I wouldn't turn down a 5.3 if you find one for good price, either one will out perform a tired old 350 and 5.3 might return better mpg.

Thanks, you make a good point about the transmission and I did check the fluid of the trans, although it was not idling or at temp, it was over full and didn't look "quite right". For price of fluid and a filter it would be a good insurance as I won't be out any extra unless the transmission is no good to begin with. The P.O. said it was good, for whatever that's worth.
I also agree with you about the 5.3L, I would certainly consider one if the deal was right.

 

[rustybottoms88]

Well Tuesday night I got the transmission fluid and filter changed in the truck. The fluid was alittle off color like it might have some water in it. The clutch material in the pan wasn't real concerning pretty normal IMO. I got all the spark plugs in and poured some gas in the bowl of the carb and it jumped to life right off the bat. It ran for a second and then it promptly flooded. So I took the carb off to investigate. PO told me he had the carb off and "rebuilt" it. I had my doubts given its condition when I pulled it off the engine.
Quadrajet fresh off the engine:

So I took it apart and found that it had all old gaskets and in general everything looked pretty dirty. It did have a new needle and seat but the seat was missing its tang and it was not attached to the float at all. So I got the numbers off the carb and picked up a rebuild kit for the Quadrajet. I watched a few YouTube videos on rebuilding the carb. I found that these wells can leak.

The carb was empty to begin with and I found some of the epoxy that had came off the biggest two wells laying in the carb so I suspected they leaked. I wanted to use some JB weld TankWeld but couldn't find any local so I opted for JB Weld StickWeld. It may last awhile maybe not?

 

[rustybottoms88]

I rebuilt the carb. When reassembling I realized someone had removed the choke completely. I put the carb on the engine and checked for spark and double checked firing order. I cranked it nothing, pulled plugs and they are wet. I'm kinda done investing time and money in the "junk" 350. I can say I tried. I picked this up today.

2002 2wd 2500HD 6.0L. 200k plus miles. It's been wrecked on the other side. Lots of goodies like a Reese bumper hitch and 4.10 gears in the rear. Parts rigs are the way to go. When I Magnum swapped my TJ the parts ZJ just kept on giving and then I sold it for few hundred bucks. I have a question for the audience, the K20 has dual tanks, I am trying to decide if I want to just use one tank with a in tank pump or put a inline pump ahead of the tank selector solenoid? I am afraid the inline pump won't last long being a puller instead of a pusher.

 

[ridenby]

Have you opened the diffs? Heck of a project. Keep updating.

 

[rustybottoms88]

I

Have you opened the diffs? Heck of a project. Keep updating.

Not yet. Thank you and I will keep updating. Maybe a week or so before I do anything else on this. I am going to do an R&R on the Jeep timing set and water pump as well as finish the a/c on it. Thanks for following along.

 

[350TacoZilla]

Heck nice find on the parts truck, shame its not 4x4 but still plenty of good stuff to pull off. Rear should be the 10.5 you were asking about, you could swap it in and re-gear the front or keep eye out for a D60 front to match whatever gears the rear has.

 

[willis_racing]

I have a question for the audience, the K20 has dual tanks, I am trying to decide if I want to just use one tank with a in tank pump or put a inline pump ahead of the tank selector solenoid?

Ran up against the same issue with my square. I bought an '87 suburban 40gal tank. That way I can ditch the saddle tanks, have more capacity than both of them anyway, and run almost all OEM part numbers for the tank, mount setup, and sender.

 

[rustybottoms88]

Ran up against the same issue with my square. I bought an '87 suburban 40gal tank. That way I can ditch the saddle tanks, have more capacity than both of them anyway, and run almost all OEM part numbers for the tank, mount setup, and sender.

The 87 Suburban tank will fit right in place? That would be nice and clean.

 

[willis_racing]

The 87 Suburban tank will fit right in place? That would be nice and clean.

I think it's some fab required. I have the tank and some straps sitting around, haven't gotten around to actually doing that yet. If you get to it first let me know how it is.

All I know for sure is it will fit between the frame rails. The fab seems pretty basic though. Here's a youtube video I found on the subject. Obviously with this you're also going to have to run a custom filler neck.

 

[350TacoZilla]

Nice part about the later suburban or blazer tank is they were fuel injected so you should be able to replace the pump itself with one for the LS pressure and drop it in tank.

 

[willis_racing]

Nice part about the later suburban or blazer tank is they were fuel injected so you should be able to replace the pump itself with one for the LS pressure and drop it in tank.

Yessir, That's the reason I got an '87 tank instead of an older one. I think the factory fuel injected tanks have a little sump in them for the in tank pump sender, or at least some kind of little slosh guard. Just works better overall than retrofitting a normal squarebody tank.
IIRC, I put a walbro 450Lph pump in mine.

 

[The Beens]

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This may not be the exact one you would need, but you can keep both tanks and use a pump like above when you go with the 6.0.

 

[willis_racing]

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This may not be the exact one you would need, but you can keep both tanks and use a pump like above when you go with the 6.0.

The only problem with going the retrofit sender route is that if you plan to keep both tanks you have to use a 6 port switching valve, because when you run EFI, you have to not only switch the fuel feed, but the fuel return as well. It seemed to me to be less effort and fuel system complexity to go with a single tank, but different strokes and all that. It certainly can be done if you just like the saddle tanks.

 

[arse_sidewards]

The only problem with going the retrofit sender route is that if you plan to keep both tanks you have to use a 6 port switching valve, because when you run EFI, you have to not only switch the fuel feed, but the fuel return as well. It seemed to me to be less effort and fuel system complexity to go with a single tank, but different strokes and all that. It certainly can be done if you just like the saddle tanks.

Or run ford sending units that switch themselves.

Return side is only open for business when there's pressure on the pump side. No switching valve, just switch the electricity to the other pump.

 

[willis_racing]

Or run ford sending units that switch themselves.

Return side is only open for business when there's pressure on the pump side. No switching valve, just switch the electricity to the other pump.

So in that case you just Y the return together at the tanks? Sounds pretty bitchin actually. I still didn't/wouldn't do it but it's bitchin

 

[arse_sidewards]

So in that case you just Y the return together at the tanks? Sounds pretty bitchin actually. I still didn't/wouldn't do it but it's bitchin

Yup.

92-96 F-series. Anything with dual tanks and the high pressure in tank pump has it.

 

[rustybottoms88]

Or run ford sending units that switch themselves.

Return side is only open for business when there's pressure on the pump side. No switching valve, just switch the electricity to the other pump.

These sending units fit on/ in the Chevy tank?

 

[PurfsMcGurfs]

Yup.

92-96 F-series. Anything with dual tanks and the high pressure in tank pump has it.

Most of these trucks have low psi lift pumps that fed a chassis mounted pressure pump if I remember right. My 460 f350 was like that (94) and my dads f150 was the same (92) I think my 86 bronco had a similar setup too.

The 87 Suburban tank will fit right in place? That would be nice and clean.

It will fit but, its huge. I opted to go with a 74 blazer tank. 25 gallons and it's shorter then the 31 or 40 gallon tanks. Originally had a 40 gal suburban tank in the bed but hated hauling that much fuel around. I'll be installing the k5 tank under the bed soon. The latter efi tanks are ok but most are set up for TBI pumps. When I get the fuel injection for my SBC, I will just get a holley retrofit pump unit. Drill a hole, lock the screws down and cap off the old fuel lines. The holley units come with or without a return port and enough options for big horse or stock efi motors. Kind of spendy but, install is easy.

 

[arse_sidewards]

These sending units fit on/ in the Chevy tank?

I'm sure it could if you had basic electrical and plumbing skills.

Most of these trucks have low psi lift pumps that fed a chassis mounted pressure pump if I remember right. My 460 f350 was like that (94) and my dads f150 was the same (92) I think my 86 bronco had a similar setup too.

Your '94 wasn't like that. They shit-canned the frame rail pump with the facelift in '92 and went to high pressure in tank. Maybe it was '93 or a mid-year changover (ford loves those) but I've never seen a '92 with the frame rail pump

 

[Grendel]

Most of these trucks have low psi lift pumps that fed a chassis mounted pressure pump if I remember right. My 460 f350 was like that (94) and my dads f150 was the same (92) I think my 86 bronco had a similar setup too.


It will fit but, its huge. I opted to go with a 74 blazer tank. 25 gallons and it's shorter then the 31 or 40 gallon tanks. Originally had a 40 gal suburban tank in the bed but hated hauling that much fuel around. I'll be installing the k5 tank under the bed soon. The latter efi tanks are ok but most are set up for TBI pumps. When I get the fuel injection for my SBC, I will just get a holley retrofit pump unit. Drill a hole, lock the screws down and cap off the old fuel lines. The holley units come with or without a return port and enough options for big horse or stock efi motors. Kind of spendy but, install is easy.

Fuck that noise. Single tank, big tank and be simply done.

I did the Burb tank in so many different trucks it's not funny.

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Hole saw out the old sending unit boss, center that ring and TIG it.

OR

Rick's Hot Rod Shop 27003 Rick's Hot Rod Shop Fuel Pump Retainer Rings | Summit Racing

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Install this, with an o-ring and a lock ring.

JEGS 159082: High-Performance Fuel Pump Module for 2010-2015 Chevrolet Camaro - JEGS

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Can get them at the parts stores.

If you only want to run one line up front:

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Fuel sending unit matches the gauge, pump is more than enough fuel and runs 100K miles. You can use factory wiring to the pump and let the ECM control it.

A 52G stainless tank from an M932A2 with one of those rings in stainless and a pump will fit between the rails...

 

[PurfsMcGurfs]

Fuck that noise. Single tank, big tank and be simply done.

I did the Burb tank in so many different trucks it's not funny.

Earl's Performance 166021ERL Earl's Performance Late Model USCAR Fuel Pump Module Mounting Rings | Summit Racing

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Hole saw out the old sending unit boss, center that ring and TIG it.

OR

Rick's Hot Rod Shop 27003 Rick's Hot Rod Shop Fuel Pump Retainer Rings | Summit Racing

Free Shipping - Rick's Hot Rod Shop Fuel Pump Retainer Rings with qualifying orders of $109. Shop Fuel Pump Mounts at Summit Racing.

www.summitracing.com

Install this, with an o-ring and a lock ring.

JEGS 159082: High-Performance Fuel Pump Module for 2010-2015 Chevrolet Camaro - JEGS

High-Performance 106 gph Fuel Pump Module for 2010-2015 Chevrolet Camaro

www.jegs.com

Can get them at the parts stores.

If you only want to run one line up front:

Summit Racing SUM-230151 Summit Racing™ Universal LS Fuel Filter Regulators | Summit Racing

Free Shipping - Summit Racing™ Universal LS Fuel Filter Regulators with qualifying orders of $109. Shop Fuel Filters at Summit Racing.

www.summitracing.com

Fuel sending unit matches the gauge, pump is more than enough fuel and runs 100K miles. You can use factory wiring to the pump and let the ECM control it.

A 52G stainless tank from an M932A2 with one of those rings in stainless and a pump will fit between the rails...

That's definitely an appealing option for an LS swapped rig when you have a donor truck. Good info.

 

[PurfsMcGurfs]

Your '94 wasn't like that. They shit-canned the frame rail pump with the facelift in '92 and went to high pressure in tank. Maybe it was '93 or a mid-year changover (ford loves those) but I've never seen a '92 with the frame rail pump

You're probably right, I havent had those trucks in well over a decade. The 86 definitely had the lift pump, I replaced both pumps in that piece of shit.