1971 K20- project just get driveable!!

[Ol Blue K20]

The k20 is looking good and nice find on the parts truck.

[DeadheadNM]

Jud how's the rear bumper on the new parts truck? Looks like a cool and heavy period correct step bumper...good find on the parts C20.

[mx289]

Just read through the build.What a great truck.
I will be watching this and your others.You have some cool k20's.

And its nice to see it used as a truck.!

Tom

[Dieselwrencher]

Great work on the truck and nice score on the parts truck. It's in really nice shape. Can you go into more detail on the blower motor? I'm interested in this as I'd like to put the best one in mine before I actually make it a driver.

[Vintage Windmills]

Originally Posted by DeadheadNM

Jud how's the rear bumper on the new parts truck? Looks like a cool and heavy period correct step bumper...good find on the parts C20.

I think its pretty good. May have to use it on one of my trucks. Are you looking for one?

Originally Posted by mx289

Just read through the build.What a great truck.
I will be watching this and your others.You have some cool k20's.

And its nice to see it used as a truck.!

Tom

Thanks, good to know people are following along
After this thing is on the road, I will resume working on the blue K20. Then I may do a quickie on the 71 K20 292 truck just to get it running again. Then work in a cummins conversion lol.

Originally Posted by Dieselwrencher

Great work on the truck and nice score on the parts truck. It's in really nice shape. Can you go into more detail on the blower motor? I'm interested in this as I'd like to put the best one in mine before I actually make it a driver.

Ryan, the blower is what Rock auto had listed for both the heat only and AC trucks. It sounds like the heat only trucks originally had a weak 5 or so amp motor. This one draws about 16 and blows like a supercharger I was expecting a fuse to pop but so far so good. Course I've only run the motor about 5 minutes so far. There is a hole on the side of the motor (it must cross reference with a newer truck) that is for a little tube to connect to for cooling the motor. I could connect a tube to my heater box, but I'm not sure I want to modify the original box...

[Ol Blue K20]

I would put the tube in it and point it down just to keep the water out. It would still get air to cool it.

[DeadheadNM]

Not looking for one but thanks for asking. I really like those old, thick steel step bumpers and have one painted and ready for my K20. I actually looked into having one chromed but was told by the plating co. that as mine had the diamond pattern on top the chrome wouldn't adhere well and would fail - too bad.

[Dieselwrencher]

Originally Posted by Vintage Windmills

Ryan, the blower is what Rock auto had listed for both the heat only and AC trucks. It sounds like the heat only trucks originally had a weak 5 or so amp motor. This one draws about 16 and blows like a supercharger I was expecting a fuse to pop but so far so good. Course I've only run the motor about 5 minutes so far. There is a hole on the side of the motor (it must cross reference with a newer truck) that is for a little tube to connect to for cooling the motor. I could connect a tube to my heater box, but I'm not sure I want to modify the original box...

Thanks Jud. I think I'll just purchase one fom there and give it a whirl.

[Vintage Windmills]

Originally Posted by Dieselwrencher

Thanks Jud. I think I'll just purchase one fom there and give it a whirl.

Hey, I see what you did there

I got quite a bit done on the truck this weekend. Pretty much didn't do anything else but work on it.

Wire wrapped to keep new ducting on defrost vents:


Decided to replace the poorly engineered original pump with something more modern:


only bad thing is it loses the prime and has to be reprimed all the time. I think I will install a checkvalve or just look for a different pump. This one is technically supposed to mount directly to tank.

Rebuilding the turn signal setup:


Sig parts all cleaned up and ready to reinstall. I got a palmfull of dust out of the old one. Remember, this truck had no back window and sat in a field for a couple decades.


Column (with new upper bearing) back in and radio delete and new cig tray installed:



What? I have to fit this grommet over this speedo cable!!! Armor all (lube) and the vice to the rescue. I got it but it split the grommet a little. Next time, think I will just cut the grommet.



Hood and different inner fender back on. That was fun by myself Good thing I am stronger than I was in my 20's. Easier to put on muscle these days thankfully.


Getting real close, need to get shoulderbelts and put them in, hook up fuel sender and figure out why the dash lights are always on, then the seat can go back in. Also need to rebuild pass door mechanisms and put mirror on driver side.

[Dieselwrencher]

Great work! I always wondered if they put the grommet on before they crimped the cable ends on because they aren't real forgiving when you're trying to force that cable nut through that small hole.

[swamp rat]

Nice work!

[Ol Blue K20]

Man, that truck is looking great what a difference from what it started from....

[mx289]

Truck looks great.

Really like the look.

Tom

[Vintage Windmills]

Thanks guys, I ordered 2 of these and a lapbelt yesterday.
http://wescoperformance.stores.yahoo...t-gm-retr.html

too cold here to heat the shop with propane these days, plus I've been wiring in the bathroom project.

[Dieselwrencher]

Thanks for that link. I need to measure my seat to floor on my truck and I will be ordering some of those. I've been waiting because the others I had seen on the net looked cheesy IMO.

[swamp rat]

The set I bought thru a local vender didn't have a plastic housing on the inside belt. Its almost a two handed job to get it buckled trying to hold the inner buckle. If you can get a set with a plastic sleeve on the inner buckle side I would recommend it.

[mx289]

Thanks for the link Vintage.
The belts look really nice and 29 colors.!

Tom

[Vintage Windmills]

Belts showed up. Should have some time to work a little on the truck this weekend.

Thinking I need to:
-Install belts
-Replace front rotors and calipers (never did since debating what front axle to run)
-Check valve in wash fluid line
-Install seat
-Install rebuilt Qjet
-Hook up gas gauge

[hgs_notes]

Looking real good. I think I still need to get my windshield washer working. Kind of forgot about that. And my wipers squeak real bad too. Looks like I found a couple things to keep busy on until I can get it back on the road.

[Vintage Windmills]

Well with the big rear bumper and lift, I need to drop the hitch a little and create a custom bracket to mount it. I used the software we use at work for design (Solidworks). I'm going to weld or bolt one of these on each side. Also checked the stress at the rear bolt, which would be the highest loaded. Its not exactly detailed to the proper degree but this simplified simulation is telling me its still not exceeding the material strength (31,000 yield for mild steel), even assuming 3000 lbs is reacted on that one bolt with a little washer. The real washer will be thicker and have more area.

[hgs_notes]

Looks easy enough to build. No way will it see that kind of force all downward like that outside of an accident. It would have to be 6000 lbs downward total because you have 2 sides. And pulling force would be shared across the other 2 bolts of each side, so it should handle anything the truck is capable of pulling. It actually looks a lot like the hitch set up I have on my Jimmy.

[swamp rat]

Are you saying that with my 4" lift and 33" tires i may need to lower my hitch? I never thought much about that, can you tell me how high the bottom of the reciver hole is to the floor now and what you think would be ideal?

I do plan on buying a flatbed trailer and figured i'd need a drop hitch, but now i'm wondering if maybe there is not a drop hitch low enough.

Any help appreciated.

[Low Elco]

On these tall trucks, I've always wondered about the firce multiplier of the 4-6" drop drawbars. It's one thing to have the trailer's force in a nominally linear push/pull. Wonder how it works with a 4/6/8(!)" lever applied. Hitch looks good!

[Vintage Windmills]

Originally Posted by hgs_notes

Looks easy enough to build. No way will it see that kind of force all downward like that outside of an accident. It would have to be 6000 lbs downward total because you have 2 sides. And pulling force would be shared across the other 2 bolts of each side, so it should handle anything the truck is capable of pulling. It actually looks a lot like the hitch set up I have on my Jimmy.

Yep, but I like to estimate high on the force since in reality, loads are dynamic and fatigue issues can occur at stresses lower than the yield stress.


[quote=swamp rat;6569959]Are you saying that with my 4" lift and 33" tires i may need to lower my hitch? I never thought much about that, can you tell me how high the bottom of the reciver hole is to the floor now and what you think would be ideal?

I do plan on buying a flatbed trailer and figured i'd need a drop hitch, but now i'm wondering if maybe there is not a drop hitch low enough.

On my factory tow package k2500hd, its about 16" to the bottom of the receiver hole and its worked really well for a straight hitch on big tandems and a mild drop on smaller trailers. You can definitely get away with a drop hitch if you arent hauling very heavy loads. I looked at your hitch and its not one of the strongest setups since the mount is the shorter frame interface. That said, the mfg rating is still probably quite high but would be reduced with a large drop hitch. the drop will not cause greater stress from the tongue weight of the trailer but will when braking due to the offset and resulting momen

Originally Posted by Low Elco

On these tall trucks, I've always wondered about the firce multiplier of the 4-6" drop drawbars. It's one thing to have the trailer's force in a nominally linear push/pull. Wonder how it works with a 4/6/8(!)" lever applied. Hitch looks good!

Those arent nearly as bad as the 12" ones ive seen on some of the big lifted trucks!
wouldnt be too hard to calculate the load increase under hard braking. we could assume full deceleration in 4 seconds or so, then get ft/sec^2, then F=ma, then multiply that force by the drop distance (from frame bottom, not recvr), and divide by length of interface at frame. That will be the additional amount of force reacted by the bolts at the rear.

[swamp rat]

On my factory tow package k2500hd, its about 16" to the bottom of the receiver hole and its worked really well for a straight hitch on big tandems and a mild drop on smaller trailers. You can definitely get away with a drop hitch if you arent hauling very heavy loads. I looked at your hitch and its not one of the strongest setups since the mount is the shorter frame interface. That said, the mfg rating is still probably quite high but would be reduced with a large drop hitch. the drop will not cause greater stress from the tongue weight of the trailer but will when braking due to the offset and resulting momen


Those arent nearly as bad as the 12" ones ive seen on some of the big lifted trucks!
wouldnt be too hard to calculate the load increase under hard braking. we could assume full deceleration in 4 seconds or so, then get ft/sec^2, then F=ma, then multiply that force by the drop distance (from frame bottom, not recvr), and divide by length of interface at frame. That will be the additional amount of force reacted by the bolts at the rear.

Thanks for the info on your towing setup.

My hitch is class IV if i use a load leveler its rated at 12,000/600 without 10,000/500 I'm hoping to be able to tow a 18' tandem flatbed with another 67-72 pickup on it Or even a 24' camp trailer.

Actually looking at it i feel the hitch is stronger than the truck frame so have been a little concerned.

So by adding the brackets your making do you feel that it is stronger than using a drop hitch? lets assume i needed a 4" drop and the brackets accomplish this drop.

Hate to say it but i don't understand your formula