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

[ultrarunner]

My 85 Fully Outfitted work van came with a 305 in California...

Never had a single issue with the engine and drive it all the time.

The only thing I notice is in the hills I always take my time and drop it down a gear...

 

[Mace Canute]

If you really want to know what the engine came from originally, you can use the information from this site to nail it down.

How to decode Chevy Engine Codes

 

[George2615]

I just bought an aftermarket tach at Advance Auto parts for about $50. It has a simple 4 wire hook up ( ground, ignition hot with key on, lights, & tach) and will work with almost any ignition and 4,6,or 8 cyl. It can be mounted with a nut / bolt using the included bracket. I used two hose clamps to mount it to my steering column.

The fuel filter you have was the wrong one. Maybe yours was missing because someone took it out and installed an aftermarket in line filter. Follow the fuel line back to see if there is one.

Seems like you got a good deal.

 

[Stimw]

The fuel filter needs to be the Sintered one (sp) , it looks like a poorly cast brass thingy with fine holes in it. They don't go bad, you just wash/blow them out.
I had a 1978 GMC w/305 and didn't like the way it pulled my 23' boat at the time. I sold it and bought a 1978 Chevy w/350 and it did much better!
The 305 will get it done for now but you can keep your eyes open for a deal on a 350. It's always easier to find something when you don't have to have it.
That rearend is probably not helping either, the original sticker was lower ratio. Watch your speed too, I doubt speedo was calibrated with the change.

 

[PoorMansCat]

Nice buy. I see some folks are trying to talk you into a 350. They are easy to find and you can build a stout one for a grand, maybe less. I rebuilt a 305 for a 1/2 ton GMC, an 86 model. It was a low compression 2 bl carb engine, similar to what you have. I had the engine bored .030 and the heads shaved .015 with a light port job. I installed an rv cam with a power range from idle to 4k. Not real radical, slight lope at idle. I installed a used low profile Weiand intake matched to the cam and had the machinist match the port job done to the heads. I topped the intake with a 500cfm 4bl carb manual choke. The owner of the truck had access to a dyno. The engine made 231hp and 319tq. I was impressed. Good power for a 305. When we installed it back in the truck we threw a set of headers on it with dual exhaust. Sounded nice. The nicest part was the engine made peak tq at 3k rpm. He towed his boat and a small camper for several years with this combo. A 350 will definitely make better power but the 305 can make good power too if done right.

I was going to suggest something similar... the 305 can be used for the OP application..
Years ago I built several 305 stroker engines by using a 400 SBC crankshaft and boring the engine .030.... If one loses the horrible factory camshaft and updates the cylinder heads with decent quality aftermarket valves/springs/retainers.. The engine becomes a very durable engine that produces great torque and raises the effective working RPm range...

 

[pclausen]

I'll definitely keep the 305 for now, but keep my eyes open for a rightly priced 350. I'm sure one will show up for next to nothing well before the 305 gives up the ghost.

I picked up a 4x8 sheet of pressure treated 3/4" plywood and after ripping it in half, it brought back the sides on the dump bed. Once the panels dry out, I'll shoot them with some glossy black paint.

I also picked up a tach at Advance for $40, taking advantage of the 20% off deal that they are still running. It's a Sunpro, so it matches the other 2 aftermarket gauges already installed. I'm thinking of mounting it on the dash rather than the steering column.

I'll also keep an eye out for a dash cover panel and steering wheel. Those are both in rough shape. Same goes for the bench seat. The springs on the driver side are completely worn out and you end up almost falling out the door. I wonder if there is a cheap fix for that or would I be better off looking for another one?

 

[murphy1244]

Peter, Get a JD air ride seat >>> I would look for the straight 6 that was in there can't be beat for torque. Don't build a 305 waste of cash.

 

[pclausen]

Lol, yeah, that would be pretty cool. That would help with the rough ride for sure! I actually found a rebuilt kit as shown below:

LMC have all kind of repro and oem pieces for these older trucks.

It has been suggested that if I end up swapping the engine down the road, why not go for a big block? I see a complete 454 on the local craigslist for $350. It was pulled from a a Chevelle. Would need a rebuilt as it spun a bearing. But that is all down the road stuff. The only thing I'm going to do in the short term is to POR-15 the frame and bed as they have some bad rust spots, especially the bed. I already have a full kit that I was going to use on the 3pt blade, but it really doesn't need it.

 

[timswi]

I'd try an Edlebrock intake and a Quadrajet or a Holly 600...305's can run pretty good but not with 2bbl's on them. I've had a few of them over the years and I really had no major complaints.

A 454 would be ideal but you might be able to make something out of what you have for a few hundred bucks and an afternoon of your time.

 

[murphy1244]

I'd try an Edlebrock intake and a Quadrajet or a Holly 600...305's can run pretty good but not with 2bbl's on them. I've had a few of them over the years and I really had no major complaints.

A 454 would be ideal but you might be able to make something out of what you have for a few hundred bucks and an afternoon of your time.

How you gonna get that mixture thru those tiny valves and heads? I would use a 305 for a door stop.