> While MGB's used the same basic engine through the years, there are some
> important differences when swapping. I'm trying to get it all straight, in
> one place.
>
> 1st, the main question at the moment, then I'll try to get more of the
> details sorted out for future use:
>
> When fitting an engine from a later (Black bumper) MGB into a chrome
> bumper car, will the later engine fit using the later mounts & brackets, or
> does an earlier front engine plate have to be used, along with its brackets
> and mounts?
No problems. I have an 18V in The Green Car now, just waiting for some
more time to get everything hooked up. That 18V was last used in a '65
chassis, so I think we're covered there, modulo the known problems with
gearbox/starter/etc. on the 3-main chassis.
[Um, I've read the rest of your first message now, and I see what you
mean. Check out how the motor mounts fit to the engine and you might
not have to pull the whole front plate.--sf]
> In general:
>
> 1) There are 3 different drive shaft lengths, depending on 3 or 4 syncro,
> and OD or not. This is pretty clear.
It's uglier than that. Recall that beginning in 1965 they also changed
the differential type, meaning that there's a variable at either end of
the driveshaft. So add another column to your table. The factory
supported 3 and 4 synchro gearboxes, with or without O/D, and banjo versus
tube-type axles. But they didn't support every combination -- specifically,
they didn't support late gearboxes and banjo axles.
> 2) Transmission pilot bushing diameter is smaller on 3 main engines (And
> maybe All 3 syncro trannys?)
Yes -- all 3-synchro transmissions require a smaller pilot bushing than
used on the 4-synchro transmissions (or, well, than used on the ENGINES
that came attached to 4-synchro transmissions).
> 3) Engine rear plate may need to be changed when changing between 3 and 3
> syncro trannys. ????
Yes, I think; the starters are either of different types or in
different places. Check the floor pan shape on early vs. late
to see what that looks like.
> 4) The tranny tunnel needs to be enlarged to fit a 4 syncro tranny in an
> earlier car, due to the shifter being moved back about 4 inches on the
> later tranny.
4" might be where the shifter goes, but you don't need to cut that
much off the tunnel. I took a crescent about 1" deep (down the length
of the tunnel) and 4" wide (across the width) to fit the '72 gearbox
into the '65 chassis. If you either have time or an aesthetic sensibility,
you can do a better job fabricating a gearshift cover than I did out of
a bread pan (could be worse, could be a bed pan!) and some fiberglass.
> 5) Transmission mounts changed a couple of times.
>
> 6) Engine mounts & brackets changed to round plates on 75 and up.
Uh-oh. That's news to me. I've got a '72 18V in my '71 chassis, and
the engine mounts are the same on both. I'd assumed that the mounting
brackets would be the same across all 18V lines.
On the pre-18V motors, the motor mounts don't connect to the front plate
directly, but they're held in with big cross-headed screws that run
parallel to the crankshaft; there's an L-shaped bracket that gets the
two bolts/studs sticking out of the rubber portion of the mount. Then
there's a four-hole metal plate that gets bolted to the chassis. Is
this not the case on post-75 Bs? I've never had occasion to look...
> 7) Earlier engines don't have the mounts for alternators.
Right, and I'm not sure when the changeover happened. Note also that
the wiring harness changed between May 1971 and whenever my parts B was
built in 1972; the connectors on The Green Car wouldn't fit the alternator
that came from the parts car, so I refitted the (fortunately still sound)
alternator from the Green Car originally.
What else? You're familiar with the internals of 18V heads and blocks,
yes? And with the different front crossmembers used in post-75 MGBs to
get the front ride height up for the bumpers, etc.
--Scott
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