Converting MPC-era 4-4-2 to 3-position reverse?

[cando614]

Converting MPC-era 4-4-2 to 3-position reverse

 

MPC experts please help!  I would like to convert a 1970s vintage 4-4-2 (#8304) to 3-position reverse.  These locos all came with a double-wound field and two position e-unit.  In fact, throughout the entire decade of the 1970s, the only four-drivered steam loco to receive a 3-position e-unit was the switcher #8506.

 

Now I am aware that in this conversion, only one of the two field windings is used.  My question is more about the fitting and mounting of the e-unit.  First: Are there any Postwar e-units which have the lever in the correct position to reuse the existing hole on top of the boiler casting?  Second: I did a trial fitting of a type 100-3 e-unit borrowed from a Postwar #1615 switcher.  Although it fits neatly between the frame sides, it seems that there is no "foot room" for the lower part of the e-unit that holds the drum!  This location in the MPC-era frame is occupied by part of the plastic bracket that holds the roller pickups.

 

Note: I also have a 1970 2-4-2 #8042 which has the hollow Scout-type rollers, and I see how a 3-position e-unit could easily be installed in this early version of the chassis.  But when it was redesigned in 1972 to accommodate replaceable rollers, the plastic bracket that holds the pickups was enlarged, apparently leaving no clearance for the lower part of the e-unit.

 

Unfortunately, the plastic bracket can't be removed or modified (at least not without pulling the wheels, which I'm not equipped to do myself.)

 

Has anyone done this mod?  Does anyone have an 8506 in their collection that they could post pictures of, or describe how the plastic bracket was modified to accommodate a traditional 3-position e-unit?  It's too bad that QSI no longer offers their ACRU-E, because it would have been perfect for this application.

 

With sincere thanks in advance for your help!  -Ted

 

 

[lionelsoni]

I can't help with the mounting problem.  But I suggest that you might want to try using the entire field coil, with the two sections in series.  This will give you somewhat slower operation, which you might find that you prefer.

[cando614]

Thanks Bob!  As a prelude to installing a 3-position e-unit, I removed the 2-position e-unit that was installed at the factory.  My curiosity got the better of me, so I connected the brush lead to both coils in series end-to-end as you suggest (except with no e-unit in the circuit.)

Of course, without the e-unit, the motor only runs in one direction.  While it does run slower with, say, 10 volts indicated, I found the motor has poor starting characteristics in this configuration.  And as before, it still runs pretty fast downhill.  For my next trick, I think I may wire a couple of diodes or a rectifer into the circuit, to see whether performance and throttle response is any different on DC.

Slightly off-topic from my original post, but: In the past 2 yrs, Lionel has reissued many of the postwar steam locos with universal "Pullmor" motors (the latest being the pink 2037 "girl's engine.")  I tested one of the 2056 Hudsons and noticed that it actually exhibited decent speed control.  Not Odyssey-like, but able to maintain speed on slight uphill and downhill grades better than its postwar counterpart.  Mechanical construction is similar to the original, including a pancake-style three-pole armature and spur gear drive.  But it looked like there were a lot of electronics crammed in the boiler.  I wonder if Lionel is running these motors with DC now?  Heck, in the latest catalog, they even offered a Pullmor-motored GP-7 with Legacy command control (but not speed control.) 

If I end up having to use an electronic e-unit mounted remotely in the tender, it will mean a 5-wire connector.  It will also mean sacrificing the existing sound of steam and whistle.  At that point I might as well go whole-hog and upgrade to TMCC and Railsounds!

Thanks for your response.  Now maybe ACDX Rob or someone who has actually done this mod will chime in.   -Ted

[rtraincollector]

I'm wondering if a electronic e-unit would work like the one I had in my  8632 or otherwise know as 6-18632. now it had a dc cam motor in it so if thats not the case maybe a what they use for e-units in the lionel classic's

[ADCX Rob]

The #8304 should have room for a 671-50 or 726-51 e-unit mounted horizontally or at an angle on a homemade bracket.  You could furnish a small hidden slide switch for on-off or use just the switch & board from the 2 position(also mounted on a homemade bracket) to keep a factory "look".

[cando614]

Rob I think you posted once before that you had done this mod.  It sounds like a lot of custom work.  Would you be willing to post any pics?  -Thanks!

[ADCX Rob]

I have not done it, but am contemplating it.