Them old "Y" block 272,292 and 312's were not bad motors, just oiling problems to the rockers,-- in their day, most all of them you saw, had a top oilier kit installed.( exterior oil line to the rocker cover bolt)
Prolly with todays good detergent oils they would be ok, and not needed.
Got under the hood of a lot of them as a kid in High school pumping gas for spending money.

Thanks for all the tips and info. Something I didn't mention in my first post........ I bought the '78 Chevy I need to work on brand new in '78.

That fan blade is a counter clockwise rotating blade. It can not be flipped. You will need a clockwise rotating fan blade. If you go with another flex fan get a good one and try to find a fan shroud to put on it also.

Not to beat a dead horse,
As I said in post #2 it is a "pusher fan" and it is also installed backwards .
if flipped over, it will work as designed as far as pushing air into the back of the radiator and out the front of the truck.
The way it is installed now, the airfoil effect in negated.
I doubt it will push little more than a breeze as installed backwards.
It is understood that it is not ever going to pull air through the radiator and over the engine unless the engine is counter rotation like in some twin engine/ screw marine applications.
The OP has the correct fan in a box of parts as stated in post #5
Now why some person installed that type of reverse air flow fan is only a guess :bigthink:
And I can't agree with you more, a shroud will improve idle/low speed cooling with the proper fan.

Some engines that use a serpentine belt, and because of the routing of the belt, the water pump and fan blade rotate counter clockwise opposite of the way the engine rotates so that is most likely a fan blade for one of those engines. Not trying to start a fight but have seen this issue on a couple of junk yard motor installations.

Totally forgot about that, you are soo correct! I have two, 4.3 Gm engines here and both are reverse rotation pump/fan, with serpentine setups
They are plastic type fans and prolly @ least 10 blades or so.
Yep, have to be careful on some vehicles to get correct water pump also as some are indeed reverse rotation and on others, conventional.
Guess sometimes old age works against me.

I did a little checking on the fuel system today.

First I pulled the gas line at the carb, put the end in a tin can, and cranked for about five seconds. No gas.

Next I unscrewed the filter can. There was a very little dirty gas in the bottom, but the filter didn't look dirty, so I put it back in for now.

Then I pulled off the line coming from the tank at the carb. Gas ran out like it should.

I went back to the carb line and put it in the can again. When I cranked this time, It started filling the can.

I put the line back on, and on the third try (pouring a little gas in the carb each time) it stayed running on its own.

I haven't driven it on the road yet, but it acts like nothing is wrong.

Vapor lock? Dirt in the line that got knocked loose? :HeadScratch:

Loosen the line @ both ends and give it a good blow with the air hose, prolly crud in it.
Also don't know what kind of filter you have, but some paper ones will not pass water worth a darn if some is in the tank, ya never know if it has been sitting a while.
Also you don't know what might be in the tank, pulled some crazy things out of them over the years from kids toys to sanitary napkins:crap:

I was kind of leaning toward crud being the problem. I'll blow the line out tomorrow. I hope I don't have to pull the tank to clean it.

You might want to anyways, with my 77 van it'll run fine until I get a tank of gas, then I can't keep it running because crud in the tank gets stirred up and finds its way to the needle valve and makes it stick partway open. I'm going to run it to empty this year and then drop the tank, clean it, and seal it. I think I'm going to add a second fuel filter to the line too, one in the stock location and one at the pump. Good luck!