>Now I have some questions...
>Does anyone know if there is a five speed tranny out there that will work?
>(were there any five speed truck tranny's made in 73' or something else that
>would fit?)
>Is the L20b the same size and configuration as the L16b? I mean, how easy
>is it to swap? I am not really a mechanic, so I have no idea about either
>of these questions..
Based on the powder blue 2000 that I saw at Shasta in both '98 and '99
I'd think the last thing you'd want to do is raise the motor. As a
general point of info, the L-20b and the Z-series (except for the Z-24)
is 3/4 taller than an L-16/18. The Z-24 is another 3/4 taller still. I
know putting the bigger motors in the 510 you can have rocker cover and
stock style air cleaner interference with the hood if you aren't careful,
even though 3/4 of an inch doesn't seem like much. Some folks also lower
the rear of the motor/trans assembly, particularly when installing the
longer style 5-speeds. This pushes the front of the motor up into the
hood. Although MotorSports used to offer a replacement trans mount and
shortened drive shaft to facilitate putting the roadster 5-spd in the
510, they're long gone.
Much cheaper to go with a Z or truck 5-spd (about the same length as the
roadster unit) or the shorter (same as the 510 OEM 4-spd) so-called
dog-leg 5-spd. This trans has reverse in the left/forward position where
1st is found on most trannies, and it's not nearly as strong as the
bigger 5-spds. It does offer the advantages of being pretty much a
bolt-in swap, not needing a relocated hole for the shift lever nor
shortening the driveshaft. For the 510 swap, Experimental Engineering
makes very nice trans mounts for both the long and short transmissions.
Differences in the truck and Z trannies are pretty much different ratio
sets. Ratio sets in the Z boxes were tighter, with some of the truck
units having 1st so low as to be useless for car applications, but great
for getting a heavily loaded pickup moving with a relatively small motor.
Except for one Z-car trans that had a .75 to 1 fifth, all of them have a
.85 to 1 fifth, AFAIK. Transmissions from (NAP)Z-motored cars and trucks
can be used, but you need to replace the bellhousing with an L-series
unit (somewhat rare, I think).
The only logical reason I can see for using a downdraft on an
L-motor/roadster swap would be if there's not enough side room for SU's
with air cleaners. Using the Weber downdraft on the OEM intake requires
an adapter that raises the carb/air cleaner at least 1/2. There are also
short and long dual sidedraft (Weber/Solex) manifolds, but even using the
shorty might present clearance issues with the master cylinders. The SU
setup is far better than the downdraft, IMHO.
So, do you have the vertical room to put the L-20b in? If you're not
sure, make a couple one inch thick patties of clay and place one on domed
area of the rocker cover and on the highest area of the air cleaner and
close the hood all the way, gently. Re-open the hood and see if its been
mashed down. Push a thin stick into the clay, remove it and measure the
thickness, or just use a small ruler stuck into the clay.
Bill Kenyon (on this list, I think) has a KA-24 (12 valve?) powered 2000
that moves pretty good. Good enough to take FTOD at the Sunday autocross
at Shasta '99. If I were going to swap in a different series motor I'd
consider that. There really ain't no substitute for cubic inches, and you
get the advantages of EFI, too.
FWIW,
Ron
Ronnie Day
ronday@home.com
ron510@mac.com
ronnie_day@acd.org
___________
The ACL Group
Arlington, Texas
(817) 572-0873
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