Truck won’t Start

[71 C20 CS]

I did a full front end rebuild on everything except the engine and everything was fine except I forgot to put the spring back in my lower radiator hose and at some point it collapsed and all the coolant leaked out. It got pretty hot, but I don’t think anything cracked and the oil still looked good.

After that it would start but die after 5-10 seconds, but seemed to run fine for those few seconds with no smoke, now it won’t start and has a flame that shoots out the carb. The ignition and a pertronix distributor chip were replaced a couple years ago, and the coil, plugs and fuel pump are good.

Does anyone have a clue what is going on? I don’t know how getting it hot could change the timing and if the valves are toast wouldn’t I hear it or see smoke?

Any advice is greatly appreciated!

[HO455]

I suggest checking the basics to start.
Does it have a good spark? A spark tester would be handy to confirm strong spark.

Is the carburetor getting fuel? Look down the primary bore and wing the throttle. You should see fuel spray.

Check the timing.

Inspect the spark plugs for irregularities.

Once these are confirmed then you can move deeper into the engine. Overheating the engine can cause several issues
Loss of compression from blown head gaskets, ring failure or cylinder wall damage from loss of oil film protection.
Overheating of the cylinder head can cause improper valve closing due valve guide seizure, if the heads have hardened seats installed they can come loose, press in rocker studs can come loose.

Removing the valve covers and carefully examining the valve train would be my next step.

Good luck and please post your findings.

[71 C20 CS]

It’s got spark, new plugs and coil. An old timer told me that sometimes when a motor gets hot it can cause the timing chain to to skip and throw it out of timing, I’m going to check the timing and see if it fixes it, I’ve never heard that overheating can cause your timing chain to skip.

[Steeveedee]

Before you loosen anything up, turn the crankshaft to TDC on the timing mark. Note carefully where #1 and #6 terminals are on the cap. Then remove the cap and see where the rotor is pointing. It should be very close to one of those terminals. If not, it has likely jumped time. Unless you got it hot enough to melt the nylon off the cam gear (assuming you still have the factory cam gear) it should not have jumped time. Unless it overheated because the timing jumped. Chicken-egg deal, there.