Picked up a 1970 GMC C3500 dump truck that needs some TLC

   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #1  

pclausen

Veteran Member
Joined
May 9, 2008
Messages
1,472
Location
Nelson County, VA
Tractor
JD 5085M, Ford 1700, JD GT235
I found this one locally on Craigslist. Guy was asking $1600, but I got him down to $1200. It runs and the dump cylinder works fine although it is a bit tricky getting the PTO in gear, but once I learn the personality of the truck, I hope that will get better. :D

Here it is after I got it off my trailer:

gmcdump10.jpg


The sticker in the glove box shows the following options (notice how it originally came with a 292 cu. in. L6):

gmcdump11.jpg


It looks like it now has a small block in it, my guess would be a 350. Here are some engine pics. Can anyone help me identify what this is? It looks like it has a later model alternator and the distributor definitely does not look like its from 1970!

gmcdump13.jpg


gmcdump14.jpg


gmcdump15.jpg


It starts right up and idles nicely, but hesitates really bad when giving it gas, and it stutters and stalls when putting it in gear unless you're real careful and rev it a lot. I pulled the front 4 plugs, and they definitely looks like they should be replaced:

gmcdump12.jpg


I cleaned one of them off enough to where I could read the part number. The plugs are ACDelco R45TS.

I figured I'll start with getting a new set of plugs (whatever the above crosses to at Advance Autoparts), and a new air filter as it is very dirty (its one of those large round ones). I'll also pick up an oil filter (I guess anything that fits a 350 chevy of a 70s vintage should fit?) Maybe I'll pull the old one in the morning to make sure I get one that will work.

I run 5 or 10W30 Mobile 1 synthetic on my other gas engines. Would I be safe to run 10W30 synthetic in this, or should I stick with dino oil on this old engine?

It could also use some fresh valve cover gaskets, so once I figure out what engine I got, I'll be able to pick those up as well.

It definitely needs some work, but I think it could be a good vehicle for around my land to catch chips from my pto chipper and haul dirt around!
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #2  
Love that..I'd have bought that in a minute for 1200...Congrats on a great score.
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #3  
That is a great deal!
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC
  • Thread Starter
#4  
Thanks! The rear tires are practically brand new and it also appears to have a rebuilt rear axle and new brake lines. I took the rear shocks off as there are no brackets for them to mount to on the frame. I wonder if the original 1970 4.57 rear axle did not have shocks?

gmcdump3.jpg
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #5  
Small block 1974 and up hopefully not a 305. The engine being orange means before they went corporate so early 70s
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC
  • Thread Starter
#6  
Thanks murphy! I'm surprised the original L6 engine was replaced after only a few years, but it might have been worked hard when new. So you think that distributor is circa 1974 as well?
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #7  
If you can get the casting number off of the block that will give you the answer as to what is it. (check the driver's side of the block where the bell housing bolts up).
It looks like a great truck. I have an '83 3500 dump. They're real handy. Put some TLC on that rear brake line set up. Vibration will crack those hard lines.

SimS
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #8  
Distributor is definitely an HEI unit. No points in that one. I think they started coming out around '73. I know that I had a '74 Pontiac with it.
The spark plug number for sure rings a bell in many of the engines I tinkered with and/or swapped out of the '76 K20 & '78 K10 Chevys and '79 K15 GMC that I owned in the 80's and 90's.
Your option sticker shows a 4.57 rear, so if it's really a 4.10 now there's been a change along the way. Never messed with the heavier trucks so I couldn't tell you about the shocks. I know that the half ton 2WD's of that era had rear coils with shocks.
I see that it was originally dark green. Brings back memories of my very first vehicle. 1969 C10 with 250 CI six banger, 3 on the tree and factory wood floor in the bed. Also dark green.
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #9  
That truck is a steal!
The distributor is a HEI (stood for High Energy Ignition),one of the best most trouble free electronic ever made!
For the hesitation, with the engine off, work the throttle while looking in the carburator. It should squirt gas.
On the front of the carb where the gas line connects to it there should be a fuel filter behind the big nut. Make sure to use two wrenches, the big nut always comes loose first and twists the gas line!
Also check the distributor vaccuum advance for blown diaphragm or sticking linkage.
 
   / Picked up a 1970 GMC C3500 dump truck that needs some TLC #10  
Great deal! Good looking truck the 67 to 72 Chevy and GMC are my favorite trucks just a really good looking style in my opinion!
 
 
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