Difference between the F7 and the F9?

The four side carbody vents between the portholes are vertical rather than horizontal and there is a fifth vent before the front porthole.  However bear in mind that many F7's were retrofitted with the vertical vents.

Rusty

Another external F9 spotting feature is the headlight bezel.  The steel bezel was replaced by a thin one with a prominent rubber gasket. But nobody will notice whether your faux F9 has that feature.  In fact, I am not sure that the EMD 462 had it, as it was an upgraded F7 or F3.

As built by EMD or GMDD, things like vents, portholes, fans, and doors tend to be more specific to the model (type) of locomotive. Items such as lights, horns, grilles were optioned by individual railroads. Most railroads modified units over time, so things changed. While specific to ATSF here are 2 sources to help you determine F7 from F9:

Steve

http://old.atsfrr.org/resources/funits/index.htm

http://trainweb.org/jfuhrtrain...7Phases/F7phase.html

@L & N posted:

Things like vents, portholes, fans, and doors tend to be more specific to the model (type) of locomotive. Items such as lights, horns, grilles were optioned by individual railroads. While specific to ATSF here are 2 sources to help you determine F7 from F9:

Steve

http://old.atsfrr.org/resources/funits/index.htm

http://trainweb.org/jfuhrtrain...7Phases/F7phase.html

One still has to be careful as locomotives went through the shops.  Take the 308L for instance:

On Santa Fe's books, it's still an F7, although externally it has received the vertical side vents, FARR stainless steel grills and 48" dynamic brake typical of F9's.

Rusty

@Rusty Traque posted:

One still has to be careful as locomotives went through the shops.  Take the 308L for instance:

On Santa Fe's books, it's still an F7, although externally it has received the vertical side vents, FARR stainless steel grills and 48" dynamic brake typical of F9's.

Rusty

Modified my response to "as built". Yes railroad shops over time changed things. There would have been variations in the fleets as units cycled through. The resources above give information on as delivered.

Steve

The difference?  250 horsepower. 

All kidding aside, model designations are not always a cut and dry as us modelers would like.  On every diesel locomotive, the specification is continuously updated during the production period for any model designation.  As a result the final specification for the F3 was virtually an F7 just as the final specification for the F7 was virtually an F9.  When you get to model number changes there are more similarities than differences during that transition period. 

As always, if prototype fidelity is of interest it pays to research the specific model you are interested in.

Another F9 difference from the F7 is the front porthole.   It is moved about 1/2, toward the rear I think, on the F9.    The 48 inch dynamic brake fan is a big difference as mentioned and the I think the side grills may be different than a typical F7.

I did an opposite conversion in the 90s.   I had some of the Old Atlas Roco F9s and and Pennsy did not have F9s, so I wanted to convert them to F7s.     I ignored the fan because the amount of body work was too much for me.   I think replacing the 36 inch fan with a 48 inch would be much easier.   You would not need to worry about the area beneath the fan.    Going from 48 to 36, I would have had to get very nice body work in the area where I removed the fan.

The Roco units had steam generator stuff on the rear roof panel, and I filed and sanded all that off.    I also removed the 5th vent with sanding etc.    And I drilled out a new porthole window in the right location for the F7.    I cut off the old porthole frame and then made a patch panel from very think styrene that fit exactly between the rivet strips vertically and horizontally where the old portal was located.   finally Keil LIne, Now Scale City Designs, had a cast porthole window frames for F units which I purchased and in stalled.  

Those old rocos had cast on handrails and grabs and gigantic coupler openings.     I cut off all the cast on grabs and replaced them with fabricated wire ones.    I cut off the pilots and put pennsy style pilots on the units.   I also put antennas on them for PRR Trainphone.