mth imperial bb verses lionels bb?

I assume you want to compare to Lionel's semi-scale equivalent.  I have the Lionel Lionmaster Legacy Big Boy #4006, which with tender coupled is 30 1/8 inches by similar measure ("from tip of cow catcher to tip of knuckle coupler on rear of tender.").

 

I also have the Lionel full-scale JLC Big Boy.  With tender coupled it is 34 1/8 inches measured the same way.

If you are looking for info on the scale BB, here are some good threads.  I had to hunt them down, but many had answers to similar questions I had.

A thread about boiler overhang.

A thread about Lee running his JLC BB and photos and info about clearances.

A thread with photos of a BB on really big curves.

Lastly, a thread about the length of the last 2 Lionel scale BBs.

Thanks all I read that boiler overhang is 3 1/4" on outside curve of 072 this so far is good as I allowed 5" clearance from wall.

sinclair... thanks for the links to threads of information I needed.

I finished the back 072 curve area that is under that elevated logging line at rear wall.
not easy as had 7" of room to work installing the 072 curves man do I feel like a human pretzel!!

$oo

We have until the end of the year before these show up at the soonest.  You could of waited until I had a free weekend to help you.  I might be a bit more pliable.   I'm planning on 4" from the wall to the center rail, so hopefully that will be enough room.  I'll just have to make sure that I keep the corners free for the boiler.  Straights should be fine for facades. and brush.

The boiler overhang on the Lionel scale Big Boy is about 3.5 inches, yes, BUT . . . the semi-scale Lionmaster's overhang is only about half an inch.  The reason for this big difference is not the slightly shorter length of the semi-scale, but how it is built.  The Lionel scale Big Boy is, besides being scale, true to the prototype, a true Mallet design: the rear set of drivers is fixed to the chassis and the front set pivots at its rar end.  This makes for massive boiler overhand in curves.  By contrast, on the lionmaster, both sets of drivers pivot in their middle position, which minimizes overhang (and, to me, looks more natural).  

 

I do not know if this is so with the MTH Imperial, but I would guess it is the same way: back four of five years ago I had an RK Big Boy and it was set up just like the Lionmaster:  It was about 1/2 inch shorter than the Lionmaster but had both sets of drivers pivoting and had no more than half an inch of overhang, too.  

 

 

I bought a MTH Imperial BB a few years ago (the set with the black passenger cars) because my layout was 036 EVERYTHING, It runs good but I had to rework a lot of scenery to make the cab swing at 3". Love the engine and now I want a Challenger!