ok I know this isn't a modern vehicle by any means.

All new 6v positive ground wiring front to rear, New coil, new points and condensor, new battery.

Truck starts and drive amazing for the year IMHO, but in 4th gear around 45 MPH it seems to run like a governor is on but only sometimes, it is oddly intermittent, and hot or cold this issue may happen.

Basically I will drive along and it just seems to reach its limit and start cutting out around 45-50 MPH, and if I let off the gas it will smooth out.

Then some of the time I can run it up to 60 MPH without issue and it runs great. I don't feel comfortable pushing it past 60 as I feel that is pushing the limits as it is.

So what I am asking is what should I be looking at as the issue? I know I have a vacuum issue somewhere as I replaced the original fuel pump with a new one and still my wipers work like crap and I know they should be much smoother.

So my thoughts are either vacuum at the carb or at the distributor, but before I start tearing into things I wanted opinions. Plus I am out of town for the next week and will not have time to even look at it.

The plus is I used it to haul off a bunch of limbs from a tree I had to cut down in my front yard, wish I had taken pictures. The entire flat bed was full at at least 6-8 feet high with limbs, and did I ever get some odd looks driving to the local mulch place.

Original 329 Flat head, original carb, original 4sp, original rear end as far as I know.

 

It sounds like possibly an ignition issue, to me. Did any of this happen to begin after you changed out the coil, condenser and points?

 

Sadly no sure. Prior to working on it what little I could drive it was interrupted by a rusty gas tank, which I changed, then found my wiring was in bad state, so I changed it out. Then it wouldn't start so I changed the coil, the points and condenser then even the fuel pump. After all that it was still weird and wouldn't start till I poured some gas in the carb then it fired right up and the pump started doing its job... after a 2 day fight it ran.

 

The fuel line is the low point of the fuel system. If the tank was rusty, the lines are undoubtedly pretty full of rust and sediment. Best is to replace them, cleaning is really difficult, the rust particles set up like concrete.

 

One other thing to check is the vacuum advance on the distributor. Be careful if you buy a new one, at least one batch of these is made wrong at the vacuum line threads.

 

I'm with Ross , change your fuel line , it sounds like it is starving for fuel due to partial blockage .
You may also need to go through your carb and clean it out .
But do the fuel line first .

 

Newly manufactured condensers are notorious for being bad out of the box. It's worth eliminating that as a source of any trouble by fitting in a known good one. Although, an intermittent ignition problem would likely mean backfiring.

 

I'll be the third to vote on fuel line. I didn't see a fuel filter replacement mentioned.

 

Sorry I did replace the fuel filter (x2) it has one before the fuel pump and one after. I will replace the fuel line. That would make sense as at higher rpms it would need more fuel and it felt like something was wrong. Ugh more fuel all over me and the driveway....

 

There should be a shutoff petcock on your tank, it will at least limit the amount of gas you get out of the line. When you get the old line out, flush it into a coffee can and see if it's full of crap before buying new.

 

Sadly there is no shut off valve on my tank I am betting it was removed years ago. At least I didn't see one when I changed the tank.

 

While you have everything apart, it might be a good idea to put the petcock back in place.