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

[pclausen]

Lol, well let me try to get us back on topic again.

So last weekend I hauled about 5 loads of mulch to mom's from my pile. On the 4th load, the engine stalled when I coasted into her driveway. Started right up again and I backed up and dumped the load. I noticed the engine was about to stall when I applied to pto for the lift cylinder. Just gave it a bit of throttle and not problem.

Went back for the 5th load, and it stalled at the source mulch pile. Got it loaded up and made the 5th trip (it's only like 1/2 mile round trip if that). Engine seemed to be getting weaker and weaker. Just barely made it back to my place again. And now the engine won't start again. I figured something with the carb, but was very surprised when I could not even get it started when spraying start fluid directly down the carb. I only got it to fire very weakly on 1 cylinder, but that was barely enough get the engine turning after than the starter motor.

I only have maybe 50 miles on new plugs, wires, coil and rotor, so I doubt it is the ignition, but I suppose I'll pull a plug to see if I got spark.

What else could it be? Could the timing chain be going? I guess doing a compression test would tell me?

Man, just as I get everything else related to the chassis running great, the darn engine starts giving out...

 

[ultrarunner]

Compression, Spark and Fuel.

Unless it is totally flooded... a short of starting fluid should at least fire if the problem is fuel related.

Any chance the distributor timing changed or points closed?

Compression is first thing I would do when I had a vehicle that had sat for years and then go from there.

 

[pclausen]

I forgot to mention I went back and tried to start it several days later. Nothing, tried starting fluid again, still nothing.

I also forgot to mention that I did grab the distributor firmly and tried to turn it. It was tight. Btw, no points. I'm running a HEI one.

Here's a pic of the engine from back near the start of this thread showing the 305 mill after I cleaned it up and gave it a tune up:

I even did the HEI mod for a strong 12V source. I'll grab my voltmeter just to double check that I still have a solid 12V at the coil supply and the relay didn't go bad. Although I think with the power slowly going, I got a bottom end issue...

Good news is that I got a 350 4 bolt main sitting on my engine stand that I pulled out of a '69 GMC 1/2 ton to replace the tired 305 in the dump truck. Looks like I might be starting that rebuilt sooner that what I had planned to...

 

[bcp]

How does a compression issue happen so suddenly?

Bruce

 

[pclausen]

All I than think of is that the timing chain is shot and started jump teeth until the point there was little/no compression left. Maybe?

 

[94BULLITT]

Are you sure you have spark?

Sent from my Samsung SPH-L710 using TractorByNet

 

[Degolyerent]

Check all connections, could be pick-up coil in the base of the distributor. You would know if it jumped timing, I would rule that out. But it is easy to check that too, bring up #1 piston to TDC on the compression stroke and check the position of the rotor in relation to #1 on the cap. Most likely bad connection or pick up coil in my opinion.
John

 

[FairfaxStu]

Good news is that I got a 350 4 bolt main sitting on my engine stand that I pulled out of a '69 GMC 1/2 ton to replace the tired 305 in the dump truck. Looks like I might be starting that rebuilt sooner that what I had planned to...

Probably not a bad idea. I would keep my options open and ask myself could I rebuild it cheaper than this:

Chevrolet Performance 10067353 GM Goodwrench 350ci/260HP Engine & Packages

That is a surprisingly decent price for something with a 3 year warranty.
-Stu

 

[Stimw]

Check the rotor button. The HEI is so hot that it can jump a path to the distributor shaft right through the plastic!!

A timing chain usually does not jump slowly.
I had a 1974 3/4 ton Chevy Van (customized ) with 100,000 miles on it. I hit a patch of ice at an underpass while trying to get up to speed for I-75. Engine did serious RPMS then shut down. I ended up moving the distributor and getting it to start so I could limp on home.
The engine was running so bad that it was firing out the exhaust on some cylinders. I had chrome side pipes on the Van and it burned the chrome off where the right pipe made the bend coming from under the Van!
I had to lay on 2' of snow to change the timing chain because most of it was accessible underneath. THAT'S WHY I LIVE IN FLORIDA NOW!!

 

[crashz]

I've had a 350 that would run even when the timing chain wore a hole in the timing cover. It had a lot of slop, but ran.

Even low compression or a few wiped cam lobes would fire on starting fluid. My initial guess would be ignition related as stated above. Don't rule out a worn distributor gear even.