1971 K20- project just get driveable!!

[Dieselwrencher]

That definitely is a nice trailer. Mine is 10' less than, deck surface, that and weighs 5500lbs with nothing on it. An open center trailer is nice to help secure things down too. Just weird during loading in the rain.

[mx289]

The k20 is looking great Jud.

Congrats on the new trailer.Looks great.

[DeadheadNM]

Drive it out here Jud - we can fill that trailer up with another couple of project very quickly!

[Vintage Windmills]

Originally Posted by Dieselwrencher

That definitely is a nice trailer. Mine is 10' less than, deck surface, that and weighs 5500lbs with nothing on it. An open center trailer is nice to help secure things down too. Just weird during loading in the rain.

The treadplate steel is a little weathered and worn. I actually had to put the K20 in 4x4 mode to back up on there. I guess I need the no spin and tires newer than 12 years old! I was thinking I could get some wet paint on there and sprinkle some fine sand on there.

Originally Posted by mx289

The k20 is looking great Jud.

Congrats on the new trailer.Looks great.

Thanks, I just fixed the stripped jack and the tight, missing a spring coupler on it, so liking it better now. Now on to the wiring fixes and winch repair.

Originally Posted by DeadheadNM

Drive it out here Jud - we can fill that trailer up with another couple of project very quickly!

Once you get the K20 storage and transfer lot set up, I will make some runs out there These older 4x4's sell well here in the rustbelt.

[DeadheadNM]

Sounds good - I'm closing on an 8-acre place at the end of the month...

[72 Super]

Has came along ways. Really coming together nicely!
Ray

[Vintage Windmills]

Time for an update. I worked on the truck for a few hours on Friday and overcame an obstacle. I fixed the wiring issue with patience, the factory wiring diagrams and trial and error with a multimeter. If you recall, the parking lights and dash lights were always on and I had to keep disconnecting the battery. As it turns out, there is not supposed to be a wire connected to the fuse block where it says "clstr dimmer". The factory schematics kind of stink but after noticing the dimmer switch got very hot within a minute, I determined there was 12V there at the fuse block terminal already and the circuit was complete with nothing plugged into the front of the block. The other issue was both parking lights would blink together with the turn signal on. I found a burnt/shorted bulb in one to be the culprit.

Now if I could just get the engine tuned better I'd be happy. I put a new distributor with a working vacuum advance on but it still stumbles when accelerating. I think the issue may be the carb but I haven't tried much with it yet.

I've been enjoying the nice brakes and tight front end, but haven't driven it much due to engine tuning. I may just get an SMI qjet tuned for it and know its set up properly and as efficient as possible.

To do list:
-Install 2" blocks instead of the 1" in the rear.
-Put better tailgate linkage on that doesn't bind against the box seam evertime I try to open it
-Put exhaust tail pipe back on
-Get 285's on it
-Install a shock on the front steering bar
-Alignment
-Put the breather cap in the HO52
-Paint interior door panels black and install

[y5mgisi]

Really cant wait to see it with the 285s!

[Vintage Windmills]

Originally Posted by y5mgisi

Really cant wait to see it with the 285s!

Yep!

I upgraded the rear lift blocks from the 1" aluminum to the 2" iron ones shown below. The truck is now pretty level, could use a little sag in the front to make it even better though. The skyjacker 2.5 springs are more like 4". I also now like the amount of excess thread better and its good to get rid of the soft aluminum with the heavy loads I may haul.

[DeadheadNM]

Jud - Where did you get the lift blocks from? I may use a set for my sagging GMC as a bridge before a new set of leaf springs. Keep the pics coming. Best, Pete

[Vintage Windmills]

Originally Posted by DeadheadNM

Jud - Where did you get the lift blocks from? I may use a set for my sagging GMC as a bridge before a new set of leaf springs. Keep the pics coming. Best, Pete

Pete, they are superlift kit 3225 but I used my heavier skyjacker U bolts. Kit 3225 is for a 6 lug truck so you may want a different kit to get stronger U bolts if you aren't using your own. I believe all the blocks are the same. Notice Summit doesn't specifically list a kit for our trucks but my blocks are very beefy and fit great except I did have to grind down the nub some to get it to drop down into the Eaton. How's your K20 liking its bigger yard?

[DeadheadNM]

Thanks! The K20 fits in well here! It looks nice in the pasture. Hope to break ground on a shop in the spring.

[Vintage Windmills]

Well no luck tuning the engine better and I did more root cause analysis. Cylinder #4 has a bit lower compression and a leakdown test indicates its leaking out the exhaust valve. I'm still surprised it won't fire since compression is still around 135 compared to the other cylinders at 155 to 160. I did all testing on a cold engine. It has good spark.

Seems like the head needs to come off, would be a good time to upgrade so I don't have to keep adding lead substitute to the gas. I'm kind of on the fence about what to do, crate engine or redo heads. Can the heads be changed with the engine in the truck? I'm really looking for the cheapest easiest at this point. I've got other trucks now that I'd rather put more time and effort into.

Still managed to haul some trailers for firewood hauling with 7 cylinder power! Pics in a bit

[swamp rat]

Did you try new spark plugs cap and rotor? Or a different wire? Try swapping a wire from another cyl to see if the cyl fires and the other now does not. Then try swapping plugs from another cyl too. Sometimes even a new plug can be bad.

Yes you can pull heads while in the truck. But keep in mind that fresh heads on a warn out bottom end will ultimatly make you burn more oil on decel and make more blow by into the crank case and in general will be a smoker. That said i dont concider 155 to be a bad compression number but don't know what your engine was when fresh.

But to hazzard a guess i'd say new heads with hardened valve guides and umbrella seals would keep you on the road for a while.

[Vintage Windmills]

Originally Posted by swamp rat

Did you try new spark plugs cap and rotor? Or a different wire? Try swapping a wire from another cyl to see if the cyl fires and the other now does not. Then try swapping plugs from another cyl too. Sometimes even a new plug can be bad.

Yes you can pull heads while in the truck. But keep in mind that fresh heads on a warn out bottom end will ultimatly make you burn more oil on decel and make more blow by into the crank case and in general will be a smoker. That said i dont concider 155 to be a bad compression number but don't know what your engine was when fresh.

But to hazzard a guess i'd say new heads with hardened valve guides and umbrella seals would keep you on the road for a while.

Finally looking at this again now that winter is here and its harder to do stuff outside. Have shop time now. It had good spark when cranking with the plug removed. I'm still going to try a different plug and wire since its the easiest. Have you ever seen a plugged intake manifold on one port? Its like its not getting any fuel...

[Vintage Windmills]

I tried a different plug and wire and still the same thing, won't fire on #4. I was wondering if the intake could be plugged but after looking at it, I doubt it. Cylinder #1 and #4 are off the same runner and #1 runs fine. Also I do get some compression on #4 so it must be drawing air in through the intake valve and if it does that, fuel would be in the air. I guess the compression is just low enough to not fire. So now I need to decide if I want to put new heads on, just buy a crate engine, or drop in the 502 HO out of the crew cab that is probably getting a cummins. I think the 502 is too much investment for this driver, should save that engine for a prettier truck or muscle car or just sell it. I'm leaning towards just doing the heads since that would probably be the easiest and I may not keep this truck very long. I've got too many trucks.

[SS Tim]

Did you perform an actual measured cylinder leakdown or just pressurize the cylinder to see ifit leaks?
Without a borescope its hard to tell but have you verified the valve is opening.

The 502... well Christmas is just around the corner. If you need my shipping address.... :-) Kidding!

[Dieselwrencher]

LMAO Tim! I'd probably redo the heads or put a good used engine in it if you plan to dump it anyway.

[Vintage Windmills]

Originally Posted by SS Tim

Did you perform an actual measured cylinder leakdown or just pressurize the cylinder to see ifit leaks?
Without a borescope its hard to tell but have you verified the valve is opening.

No flowrate was measured, I don't have a cfm gauge. I had the rocker covers off and the valve sure looks like its moving

Originally Posted by SS Tim

The 502... well Christmas is just around the corner. If you need my shipping address.... :-) Kidding!

Send me a CST K20 and it will be on its way

Originally Posted by Dieselwrencher

LMAO Tim! I'd probably redo the heads or put a good used engine in it if you plan to dump it anyway.

Hard to find shops around here that do that. This part of MN is a throw it away and buy new area unfortunately. I see NAPA has reman head or new heads, but there are so many options I'm not sure which is the one I want. Need to research that.

[Littletony]

Jud, I am going to have to check up on you more. You are moving right a long with the truck.
I am finally getting time to work on mine, I just striped it down to start rust repair. I also discovered what was causing the skip/stumble mine had. At some point it bent the intake valve for cly #3, which cracked the head in the valve guild area. Hopefully at some point I will have a build thread going.

[Vintage Windmills]

Originally Posted by Littletony

Jud, I am going to have to check up on you more. You are moving right a long with the truck.
I am finally getting time to work on mine, I just striped it down to start rust repair. I also discovered what was causing the skip/stumble mine had. At some point it bent the intake valve for cly #3, which cracked the head in the valve guild area. Hopefully at some point I will have a build thread going.

Hi Tony, good to hear from you. I miss the GMC k20 and have been looking since that one and haven't found another. Hope you do a build thread but understand if you don't since they do take time.

Its a coincidence but I'm also having engine issues due to the valve on one cylinder on my K20. Its on hold now until I figure out what to do. I can't decide what I want to do for the engine. I think its down to just buying the crate 350 for $1570, the crate with roller cam and vortec heads for around $2k, and sometimes I'm tempted to do a mid 90's TBI swap. Too many options!

[Vintage Windmills]

Well, jegs dropped the price on their 260hp GM crate engines so I couldn't pass it up. New engine will be delivered tomorrow! Then it will be time to yank the old one, and start the swap... as soon as I have time and can get a hand or two

[y5mgisi]

How much was it, if you don't mind me asking?

[Vintage Windmills]

$1344 to my door. Just didnt make sense to rework the current engine at that pprice

[y5mgisi]

No kidding! Thats not bad at all!