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I have installed a 1962 261 in a 1950 chevy 1 ton pickup. The radiator I have is out of a 1955 1 ton 1st series truck. I have installed a water pump relocation kit to use the earlier/higher pump. I have a 4 blade fan that is approx 15" diamter and fits the center hole on the older style pump... the fan is a factory chevy fan.

my problem.. there is zero clearence between the radiator and the fan... is the 55 radiator slightly different in the mounting (compared to 1950)to cause the interference? or is the radiator to wide to use in this application? Are 1/2 ton units not as wide? Is there another factory fan that fits better?

Any help would be appreciated as I am "hopefully" finishing the install this coming weekend.

There is not a lot of clearance on these anyway but you could have a HD radiator in the truck. I have seen many of the bigger trucks with this option and it would be thick enough to interfere. They are 17-1/2 qt I believe and have an extra row in them.

I have a 52 3100 with a big radiator out of a 47 or 48 big truck (larger fenders/hood), and it fits perfectly with the original fan. Does your relocation kit place the fan forward significantly?

There should be plenty of clearance with my adapter and a stock radiator. In fact the fan will be in the factory position.
I suspect Brad is right.
I know of no fan that sits farther back.
I have seen pumps that did not have the pulley pressed on far enough. Do your pulleys line up?

I do not know if pump has pressed on far enough... is there a spec dimension from back of casting to front of pump pulley face?

The radiator is a stock 1955 from a 1 ton panel

Are 1 ton radiators a different dimension than a standard 1/2 ton model?

1955-1st series?
If yes, it is like the 1954.

Yes, the 1-ton radiator was either 0.5" thicker/deeper than a 1/2 or 3/4 ton (2.5" vs 2.0"); and, the optional 1-ton radiator was 3.0" thick/deep.

The 1-ton radiator had a different mounting frame.

I checked the dimension on my radiator... the top tank is 4" wide and the finned core is 3 1/4" wide.... is this the cause of the interference with the fan?

I would like to use the 1 ton radiator if possible but it sounds as if I would need to move the radiator forward to clear everything... correct?

If I switch to a 1/2 or 3/4 ton radiator will I need to get the mounting frame also?

It is hard to determine what is causing your clearance problem without seeing photos of the radiator and water pump and fan blade. But, if the extra thickness of the radiator is on the engine side of the radiator housing/frame, yes, that would result in the radiator being closer to the fan.

Not knowing what mounting frame you have, no one can tell you if need to get a different mounting frame for correct installation of a 3100 radiator.

I looked at mounting frames last night.. I have one from a 1955 1 ton panel, and one from a 1950 1 ton pickup. They look identical in layout and dimensions. I dont have any other radiators of this vintage to compare (though dimensions show it is the wider 3" deep core). Does anyone know if the extra depth on a 3" core is towards the engine or towards the front of truck?

Is there a difference between a 1955 and a 1950 radiator as far as mounting setup? I know a number of changes were made in 1954 and didnt know if slight changes were also made in radiator setup.

I will try and get some pics posted this weekend.

If its an original radiator there should be a tag spot welded to the upper tank, GM used Harrison radiators in the 40s-50s and that plate should have 'Harrison' and under it a model number. If its not Harrison I don't think that it's a stock or even GM radiator.

I went to the junk yard today (finally warmed up) and measured a 1/2 ton... it looks like the extra deep deep radiator (3") is 3/8-1/2 deeper towards the engine side.. which corresponds with no clearence with fan.

I also looked and could not find any Harrison tags or stampings on radiator.. it looks original and has the correct mounting but could not find and identification... maybe a prior rebuild?

Now probably looking for a new radiator as the junk yard stuff was ... junk. Anyone have any feedback that recently bought one? best cost? quality issues with some?

I bought part number 78-011 from www.classicparts.com I have been running it since 2011 with no issues, bolted right up.