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Old 04-07-2011, 10:41 AM   #1
flyingtim01
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New guy with '71 K20

Hey guys!

New guy here here with a field-fresh '71 Chevy K20. I'm going through the whole thing to try and identify exactly what I have, and I've got a few questions.

I haven't yet scraped the crud off the casting number and craned my neck to be able to see it, but according the the stamped number on the pad on front of the motor, I think its a 350 out of a '76. The stamping is K0725TXD, if I remember right. Anyway, I've seen some other shots of the glovebox stickers, and it seems like trucks that were equipped with a 350 were noted as such on the sticker, and mine mentions nothing about what engine it would have come with. Though, the sticker only listed options, right? So was a 350 standard for a 3/4 4x4 in '71, or is this really a motor from a '76? I know, I know, I've gotta check the casting number, but I just thought I'd throw this out there and see what you guys have to say.

I'll take some pics this afternoon and get them up here.
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Old 04-07-2011, 02:15 PM   #2
CPNE
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Re: New guy with '71 K20

If VIN starts with KE and no optional engine on SPID, original engine was a 307

If VIN starts with KS and no optional engine on SPID, original engine was a 250
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Currently on or near the homestead:

67 Chevy SWB 2WD stepside 350/3 on tree (Pat's)
67 GMC SWB 2WD Fleet 402/auto (Brian's under construction)
67 Chevy 3/4 ton 2WD 402/auto (Business Hauler)
67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC)
68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC)
70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC)
71 Chevy SWB stepside (Crushed by tree - parts donor)
72 Chevy 3/4 ton 4WD (Parts donor)
72 Chevy 3/4 ton 4WD Suburban (Parts Donor)
72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC)
81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler)
82 Camaro Z/28 355/Super T-10 (Pat's toy)
93 Caprice 9C1 (Brian's Cop Car)
02 Toyota Camry (Reliable but a souless steel and plastic hulk)
2011 2SS RS Camaro M6 Factory Hurst Shifter

Maybe I need to sell some of this crap

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Old 04-07-2011, 08:40 PM   #3
flyingtim01
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Re: New guy with '71 K20

Great, cpne, just what I needed to know. Although I see that the number in the glovebox starts with KE and the number on the plate on the door jamb starts with CKE and they're different numbers besides. Im guessing they should be the same and something is amiss here?
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Last edited by flyingtim01; 04-07-2011 at 08:41 PM.
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Old 04-08-2011, 06:20 AM   #4
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Re: New guy with '71 K20

In '72 GM added a new prefix to the truck VINs to tell GMCs from Chevys. Chevies got a C and GMCs got a T. So a Chevy V8 4wd 3/4t went from KE2 to CKE2 and GMCs went to TKE2. so,yours has recieved a cab swap using a '72 4wd cab. The frame VIN is located on the top of the driver side frame rail back near the cab.
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Old 04-08-2011, 07:45 AM   #5
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Re: New guy with '71 K20

Quote:
Originally Posted by flyingtim01 View Post
snip
I haven't yet scraped the crud off the casting number and craned my neck to be able to see it, but according the the stamped number on the pad on front of the motor, I think its a 350 out of a '76. The stamping is K0725TXD, if I remember right. Anyway, I've seen some other shots of the glovebox
snip
If I remember correctly the engine that was in my truck when I got it had a TXD suffix. The good news - if my memory is right - is that it is could be a 4-bolt main 350. Not that it matters. Some guys get all hot and bothered when they get their hands on a 4-bolt main 350. If the casting number is 3970010 it could be either a 2-bolt or 4-bolt. The only way to know for sure is to drop the pan and count bolt heads.

Mine is currently on the shop floor waiting for me to put it on craigslist. It simply couldn't keep oil pressure so it needs a going through. I replaced it with an old-school 383 build. My machine shop guy had a 400 crank laying around so I put it to use in an old 350 I had laying around.

That VIN on the frame is a partial VIN. I believe all it is going to have is a "K" for 4wd, another letter for the plant it was manufactured at, and the sequence number from when it rolled down the line. Not real helpful other than to let you know whether or not the cab on it came with that frame.
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Old 04-08-2011, 11:33 AM   #6
CPNE
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Re: New guy with '71 K20

Also, if it had the base engine, either 307 or 250, a K20 had 4:56 gears by default, unless an optional ratio is listed on the SPID. Looking forward to pics
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Currently on or near the homestead:

67 Chevy SWB 2WD stepside 350/3 on tree (Pat's)
67 GMC SWB 2WD Fleet 402/auto (Brian's under construction)
67 Chevy 3/4 ton 2WD 402/auto (Business Hauler)
67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC)
68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC)
70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC)
71 Chevy SWB stepside (Crushed by tree - parts donor)
72 Chevy 3/4 ton 4WD (Parts donor)
72 Chevy 3/4 ton 4WD Suburban (Parts Donor)
72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC)
81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler)
82 Camaro Z/28 355/Super T-10 (Pat's toy)
93 Caprice 9C1 (Brian's Cop Car)
02 Toyota Camry (Reliable but a souless steel and plastic hulk)
2011 2SS RS Camaro M6 Factory Hurst Shifter

Maybe I need to sell some of this crap

Yet another Bozo with a sawz-all
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Old 04-08-2011, 11:59 AM   #7
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Re: New guy with '71 K20

welcome, moved over to the 4x4 section....

we like pictures
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Old 04-08-2011, 01:53 PM   #8
flyingtim01
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Re: New guy with '71 K20

Ill certainly get some pics up this weekend. I've got some parts coming in today that should make it relatively road worthy, so I'm predicting a loud test drive this weekend. It backfired last week and blew out one of the mufflers.

Thanks for the vin info, I guess I just want to know which vin is correct, sounds like the tag on the frame will tell me that.
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Old 04-10-2011, 06:06 PM   #9
flyingtim01
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Re: New guy with '71 K20

So here are some pics of the rig.















I love the tall, skinny tires and fell right in love with these, too bad they're on the old suicide rims and pretty dry rotted:



I spent most of the day yesterday fighting with the old MC and booster. The truck had a lousy brake pedal, the pedal didn't return as it should, and when the pedal was all the way down the engine would almost die like there was a huge vacuum leak. All those signs pointed to a new MC and booster. It took most of the day to do that 'simple' job, the pivot pins were so stuck I had to take the mounting bracket off the firewall and completely disassemble the pivot assembly to get the old booster and push rod off. Then you break a couple of fittings off old rusty brake lines...and pretty soon you're ordering the front brake line kit and proportioning valve you should have ordered with the booster and MC. Oh well.

Today was mostly cleaning and trying to figure out exactly what I have in this truck. The guy I brought it from said it was an old line truck, which explains the PTO winch and the rack body. From what I've read though, all the trucks that had came with a PTO winch from the dealer had a cable operated PTO that was mounted on the dash, and was only power in. Unless it was mounted on the Tcase, but those seem to be pretty rare. Mine has a lever mounted on the floor, not a cable through the dash. You can see it pretty well here.



The shifter for the PTO is pretty touchy. Matter of fact, I didn't realize that I kicked it into gear yesterday and when I went to start the truck, it wouldn't turn over. Starter engaged and just a loud hummmm...after my heart started beating again I realized that the PTO was in gear, the hook was hooked onto the fairlead and it wasn't going anywhere. I couldn't pull the winch out of gear out at the winch (still can't, actually) so thats when I decided to figure out the PTO once and for all. This morning, I took the hook off the cable before I did any more damage to anything, and figured out that the PTO does indeed have a forward AND reverse! From what I've read those are pretty rare. So that was a pretty pleasant surprise. Going to need a new cable though. I don't think I'd want to pull much of anything with the frayed thing thats on the drum right now. I can't see a name on the PTO, but there are numbers stamped into the tag. Maybe they mean something to someone here? The winch itself is a Braden, I'm guessing a Chelsea PTO.







There was also another pleasant surprise. The glovebox had turned into a mouse Hilton over the years, and when I cleared out all the old seat stuffing, cotton, turds and acorns, I found the original vin plate that must have been on the old cab. It matches the sticker in the glovebox.



When I got the truck, it had been run by a gas can on the motor for a long time, idling away while it pulled the POs wrecks around his yard, up hills, out of swamps, etc, so there was a lot of work to be done with the fuel system. The tank looks nearly new (for a 40 year old truck) and it didn't exactly stink of varnished fuel, so I topped it off with 10 gallons of hi test, replaced the melted rubber line between the tank line and the hard line that runs up the frame rail, put some new rubber pieces in at the fuel pump and tightened up the fuel filter, and it started right up. I'm guessing that it wouldn't start one day, due to the fuel line under the truck turning to mush, and he just started feeding it by gravity. I even found an old gas can label sitting on the intake. Really? All that for a 50 cent piece of fuel line? Anyway, it started but ran like crap off idle. It back fired but good once and:



Now I've got a really loud truck on one side that fills the cab with fumes.

I took the carb off to give it a quick spray with some carb cleaner and take a look inside, but only got as far as the mixture needles. It look like the PO ran them in with an impact gun. They had big steps right in the middle of the needle. Luckily I had a couple old steel needles that weren't the greatest, but at least they were smooth. I threw them in and tossed the carb back on, and it seems to run pretty good. It does a lot of backfiring at higher RPM, so I'm thinking that maybe there is a restriction in the system somewhere. Maybe the old inline filter, maybe the screen in the fuel nut, going to have to go through all of it. Also, I'm pretty sure this is a later model motor. The fuel pump has a return line on it, which has been plugged. I don't think our trucks had return lines, I know mine has no provision for one. I'll probably pick up the right pump for it too, one less thing to worry about leaking.

I ripped out a lot of the old carpeting. I think that it was indoor/outdoor stuff that was really horrible. Carcinogenic. Once out, I could see some previous repairs.



I suppose I can't really complain...the toe board is really solid, as is the rear floor of the cab. But the front floors have had it, as have the doors. Rotted clear through the bottom, forget about doing just door skins. I'll have to keep my eyes open for a couple good doors. Also, I didn't get a pic of it, but the metal headliner is rotted through right where the rearview mirror would bolt up. Looks like water was coming in through the windshield seal. Are those inner pieces repop'd?

So all in all, it was a good weekend for the truck. Once the brake lines come in, I *should* be good for a test drive. I'll be changing all the fluids (did an oil change this weekend too...that was the blackest oil I had ever seen. Made me feel good about putting a whole quart of Marvel in with the fresh oil) and I have gaskets for the front and rear end and about 17 quarts of gear oil. I also noticed that the balancer is wobbling pretty good, and something has started whining in the front of the motor, probably time for a water pump and hoses and all.

I don't particularly care for how the rack body looks, though I love the functionality of it. The steel deck is starting to rust through in some places, so I think that I'm going to cut the steel center section out and replace it somehow with some pressure treated lumber, and build some shorter wood sides that will fit into the stake pockets. That way I can use it more like a pickup if I need a load of fill or something, and I can put the racks back on if I'm hauling wood or brush or something.

So thats the beginning...I'm already in love with this thing, so it looks like I'm here to stay!
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Old 04-11-2011, 01:07 PM   #10
CPNE
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Re: New guy with '71 K20

Thanks for the pics. Looks a lot like some of the "relics" I've brought home a time or two. Have fun with it. Are thos blue spicer lock outs as nice as they appear in the pics?
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Currently on or near the homestead:

67 Chevy SWB 2WD stepside 350/3 on tree (Pat's)
67 GMC SWB 2WD Fleet 402/auto (Brian's under construction)
67 Chevy 3/4 ton 2WD 402/auto (Business Hauler)
67 Chevy 1 ton dually 2WD 396/4 speed (Former business hauler, Needs TLC)
68 Chevy 1/2 ton Suburban 2WD 250 six/3 on tree (Brian's Needs TLC)
70 Chevy 3/4 ton 4WD 350/4 speed (Pat's - Disguised as a 68 GMC)
71 Chevy SWB stepside (Crushed by tree - parts donor)
72 Chevy 3/4 ton 4WD (Parts donor)
72 Chevy 3/4 ton 4WD Suburban (Parts Donor)
72 GMC 3/4 ton 4WD 292 six/4 speed (Mine - Disguised as a 67 GMC)
81 GMC 4WD Dually Dump Body 350/4 speed (Business Hauler)
82 Camaro Z/28 355/Super T-10 (Pat's toy)
93 Caprice 9C1 (Brian's Cop Car)
02 Toyota Camry (Reliable but a souless steel and plastic hulk)
2011 2SS RS Camaro M6 Factory Hurst Shifter

Maybe I need to sell some of this crap

Yet another Bozo with a sawz-all
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Old 04-11-2011, 03:34 PM   #11
flyingtim01
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Re: New guy with '71 K20

They're definitely not bad. The drivers side seems to work just fine, but the passenger side doesn't seem to want to unlock all the way. I guess thats better than last week when it wouldn't move out of the lock position at all. I soaked everything in penetrating oil and rocked the truck back and forth a little bit and got it to move, though I'm thinking its still going to need to come off and get cleaned up. From what I can tell, the truck has just sat for a long time and things are rather stuck. Passenger side window won't roll down, wing vent won't open. Heater controls won't move at all, though there very well may be a nest in it, judging by the ton of acorns I vacuumed out of the cab. No matter, the heater core has been bypassed, so I'm sure that leaks. Cab vents don't look like they've moved in a long time. Its just going to take some time to get things moving again, I think. Like the lever on the winch. Its been in gear so long it doesn't remember how to be out of gear.
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Old 05-15-2011, 03:50 PM   #12
flyingtim01
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Re: New guy with '71 K20

Okay guys, I've been working at it for weeks now, and I'm kind of at the extremely frustrated stage, where I don't even want to look at it. Here's what I've been up to:

*New MC and Booster
*New front hard lines and hoses
*New proportioning valve
*New calipers, pads and rotors
*New wheel seals, fresh packed bearings
*Rebuilt Spicer lockouts

It runs halfway decent, I guess, but the 2 barrel intake has two broken studs, so I can't really tighten down the carb and make sure this thing has no vacuum leaks or anything. I got an Edelbrock performer and a Quadrajet for it. Cleaned up the intake and rebulit the Qjet, so they're ready to go on. Looks like I should probably also spring for a water neck, t-stat, water pump and hoses.

The current issue right now is the brakes. As I said, its got new hard lines and hoses, calipers, prop valve, master cylinder and booster. Here are the issues I'm having with the brakes:

1) When I pump up the brakes and then crack the front bleeders, fluid is constantly dribbling out of them, like the MC isn't fully releasing. I ground about 1/16" off the pushrod, reinstalled and it seems to do the same thing. I have about 1/4" free play in the pedal itself.

2) No fluid to the rears. I've ready a thousand threads about prop valves and pushing in the button in front when you're bleeding. I've taped the pin so it stays in, and still no fluid coming out the rear bleeders. I pulled the rear line off the prop valve, and just a dribble of fluid out of the valve itself.

3) I started the truck to see what sort of pedal I had. Not particularly spongy, and the truck seems to stop fine (in the driveway, at least), but at about halfway through the stroke of the pedal, the engine starts to stumble like there is a big vacuum leak. When the pedal is all the way to the floor, it seems to go away. The pedal also doesn't seem to return easily on its own, I have to pull it back up by hand so the engine won't die.

I have to admit to a brain fart, I failed to bench bleed the MC. However, the fronts don't seem to have any air in them at all, after I bled them out, and again, seem to stop the truck fine. Also, even though I mentioned that the bleeders in the front seem to always have fluid coming out of them, the calipers aren't locked up.

So, let me know what you guys think. I'd like to take it for a ride sometime this summer!
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