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

Grumpy Old Man · Jan 6, 2013

pclausen said:
Got the casting numbers and it looks like everything is indeed original:

3932386 Block 68-70 300/350hp
3932454 Heads 68-69 307/350 1.72/1.50 76cc 300hp heads
3927184 Intake 69 300/350hp truck, vette

Another engine pic after removing the air filter and fan.

Valve cover removed. Looks fairly decent.

This truck is way more rusted out than my '70. I think I'll haul it off to the scrap yard after taking the bench seat and instrument cluster out of it. Will also keep the alternator and side mirrors.

Why junk it take what you want and give it or sell it to the next guy someone is looking for that frame or something else that's still good on it !

pclausen · Jan 6, 2013

That's not a bad idea. I'll definitely try that first.

Got the engine pulled. It looks like it has been host to many a mice over the last 28 years.

murphy1244 · Jan 6, 2013

Notice the oil filter, it is the truck can.

Runner · Jan 6, 2013

Looks like the grille on the blue truck is in better shape too, might want to swap that out. By the way, I love old trucks and love this thread. Thanks for posting.

Hay Dude · Jan 6, 2013

It is a nice thread. Lots of info & photos and very little GM bashing so far......
350's were amazing engines. Arguably the most versatile V-8 ever built.
I have a buddy in Indiana that restored a nice old Chevy C-60 grain truck with a 350 in it. Still uses it.

pclausen · Jan 6, 2013

I'm going to leave the 305 in the dump truck for now and take my time tearing down and inspecting this 350 before doing the swap.

I'll put a new cam in along with long tube headers. I'm thinking this cam from Summit, which is a very mild cam meant for towing:

SUM-1100 Duration 242/252, Lift .368/.398 RPM Range Idle - 4000

I'm not limited to just the Summit brand, but they are cheap ($54.95).

The only other things I will replace unless something else is discovered when tearing it down are:

Lifters $48
Timing Chain and Gear Set $13.95
Gasket Set $16.95

So about $150 in parts, plus the long tube headers, pipes and glass packs. But then I think I'll have a strong running dump truck.

Grumpy Old Man · Jan 6, 2013

pclausen said:
I'm going to leave the 305 in the dump truck for now and take my time tearing down and inspecting this 350 before doing the swap.

I'll put a new cam in along with long tube headers. I'm thinking this cam from Summit, which is a very mild cam meant for towing:

SUM-1100 Duration 242/252, Lift .368/.398 RPM Range Idle - 4000

I'm not limited to just the Summit brand, but they are cheap ($54.95).

The only other things I will replace unless something else is discovered when tearing it down are:

Lifters $48
Timing Chain and Gear Set $13.95
Gasket Set $16.95

So about $150 in parts, plus the long tube headers, pipes and glass packs. But then I think I'll have a strong running dump truck.

those rams horn cast exhaust manifolds had some pretty good flow and the right back pressure for torque back in the day .

crazyal · Jan 6, 2013

Grumpy Old Man said:
those rams horn cast exhaust manifolds had some pretty good flow and the right back pressure for torque back in the day .

That's exactly what I was thinking. I would put them on ebay if you don't use them.

Grumpy Old Man · Jan 7, 2013

pclausen said:
I'm going to leave the 305 in the dump truck for now and take my time tearing down and inspecting this 350 before doing the swap.

I'll put a new cam in along with long tube headers. I'm thinking this cam from Summit, which is a very mild cam meant for towing:

SUM-1100 Duration 242/252, Lift .368/.398 RPM Range Idle - 4000

I'm not limited to just the Summit brand, but they are cheap ($54.95).

The only other things I will replace unless something else is discovered when tearing it down are:

Lifters $48
Timing Chain and Gear Set $13.95
Gasket Set $16.95

So about $150 in parts, plus the long tube headers, pipes and glass packs. But then I think I'll have a strong running dump truck.

you have it out you have to replace the clutch pressure plate and throwout bearing or you will be replacing them in 2 weeks ! it never fails to go bad after its running good and you think your done .