So both the carb, and distributor, are the correct stock OEM issue? I was under the impression the dizzy was supposed to be a dual diaphragm unit in those, and this was maybe why the trouble. But, that's why I hedged, I dunno anything other than about 99 and 44/100ths per cent of the folks with the older Y blocks ditch the Loadomatic and install a '57+ dizzy.

edit: OK, so the dual diaphragm distributors were used on 4 barrel equipped cars only. The Loadomatic used different vacuum advance techniques for idle or cruise, and wide open throttle, since there were no mechanical advance springs or weights. "Venturi vacuum".

Might be fun to try and repair the Loadomatic for nostalgia sake? Or not.

 

I may have misspoken, that is an original type set up but I'm not sure it is correct for that year truck. I've only seen that on the early Y block 239 and 272 motors in 54-55 passenger cars. I'm not 100% sure it was used on the trucks in 56...

Edit: I think the OP should post the pictures in the 48-56 section and see if he can get a positive ID of the year.

 

I just went thru part of this on a 312, ti was running a 4 barrel carb and the stock non weighted ,vacume only dist, I just got the correct dist with weights and vacume,although i haven't run it yet this set up is correct.
Is the carb on the OP's question the correct Tea pot set up by FOMOCO, the dist is but I believe hsi carb is not the tea pot, so this dist will not work correctly, BUT it will run the only difference between distributers is the overall degrees of advance, my 312 ran like a scallded cat with the tea pot dist on it, so I sense another problem here.

 

Some people claim that when they are setup right the teapot carb and vacuum-only advance works well, good performance with excellent fuel mileage. I dunno.

Lots of people call it "Load-o-Crapic" too. The teapot carb too has another nickname, aka "towering inferno".

 

The OPs carb isn't a tea pot, it's a 2V with the triangle mounting design and vacuum control valve. Anything about a tea pot is irrelevant and no help.

 

Then the vacume only dist should be replaced with the later one as had been stated earlier with weights and vacume to work on the different carb.

 

could be the incorect spark controle on carb. they look exactley like power valve used in later carbs.best bet is get a57 or newer dist along with corect carb. i have taken 58and newer dist and convert to ford dura spark ign,along with 57 and newer carbs. engines ar mor fuel eficent and mor power. if you ar interested have some info i could emailyou.also look for 57int,and carb.you will never get results unless carb and dit ar matched.the vacume advance only dist 54-56 never wher that great. my em is ct1940@shaw.ca