Hi,
First off, I'm presumaing that you're talking DCOE 40's here.
The answer to your question depends on exactly what GT6 head the carbs are
fitted to. Like TR6, GT6 has different port spacing, the MkIII is similar
to "late" TR6, CC75xxx to the end of the CF series. I can't speak for
european models. Early GT6 might or might not work with an early TR6 head.
FWIW, triple Webers on GT6 are pretty rare in my experience.
Now as far as making triple webers fit your TR6 - piece-o-cake. The later
TR6 (starting with CC75000) has an indentation in the inner right-hand
fender well to accomodate the later style "long runner" intake manifold.
Note: the eraly TR6 has this indent, but on the later cars the indentation
runs the entire width of the inner fender. So, if you have a post CC75000
car, you can bolt 'em right in. The situation that Malcom refers to is
related to the type of K&N that you use, there's a 3 inch tall filter and a
shorter one, I believe 1.75 inches. The shorter ones fit easily, the longer
ones take some "fitment". In fact, given the fact that there is _no
clearance_ between the inner fender and the tall style K&N, especially on
the front-most carb, the only way you can screw the top part on is by
making a hole in the inner fender... the rear carbs are easy to access,
although an offset screwdriver is very helpful for removing/installing the
air filters!
But don't let that dissuade you.
Another more suitable method to filter the air to the Webers is via an "air
box". With this setup, you make a sheet-o-aluminium to go between the
carbies and the intake manifold - you then fashion up a piece or pieces to
form up a box and then close one end and at the other end run in a pipe of
some sort and a larger air filter can be fitted as needed. This is the way
that most of the E Production road racers do it in the 'States.
I mention the air box because it is a much better solution than just
hanging three K&N filters on the carbs. It's better because you get cool
air to the carbs (if your air source is in front of the radiator, hint
hint) and the carbs will run cooler. The Webers will thank you for this.
Now as far as jetting and choke size and all that, the answer depends on
how you use the car. If you run in SCCA, then there are some limits in some
classes depending on where you run. In stock class, no Webers. Period. DSP
has no limit on induction (except no forced induction... I'll let the sea
lawyers argue about whether an airbox is forced induction). So, you could
run with 30mm chokes, even 33's if you can get the thing to run. I'll point
out that with huge chokes, the car won't run for shit except at wide open
throttle, so if this is a street car, be warned. If you run in the
"prepared class (AP)", then you are limited by the rules to 28mm chokes. I
have no idea why. This is true for E Production road racing, also.
Presumably someone on the "comp board" doesn't want pesky-ol' TR6's beating
say Miatas at the Runoffs(tm), so they limit the choke size. I'll bet with
a really tweaked TR6 motor, this limit has to account for some serious HP
loss (guestimate: 25 HP), but I have no emperical data... if someone out
there has a Desktop Dyno, this would be an interesting item to run, but
you'll need real flow numbers to actually calcualte this stuff... If you
want to run E Mod (solo II) then do whatever you want. However in that
scenario, you'll need to shed 800 pounds from your TR6 to be really
competitive... no easy task, I'll add. I can't address GT3, as I've never
seen the GT Spec book. I'll be there's no limit on choke size there, but
you have to have extremely deep pockets to play that game, so we won't go
there.
So, what to do?? Well, if you would arrange to deliver the carbs to me, I'd
make sure they got a good home. BTW, the GT6 manifold is actually different
than TR6, so if you do buy this setup, figure you're going to have to drop
$300 - $400 for an appropriate manifold to fit up to your TR6.
A better thing to do would be to find a GT6 racer (or Vitesse) and broker a
deal so that you can get your own Webers...
One last thing, to understand these carbs (Weber), you need to read a lot.
I suggest Passini (Hi Mark!) and Braden (HP Books) as a starting point.
Read Passini, then read HP to figure out what Passini just told you. Bottom
line: figure in another $500 to dyno the car and play with the jets to get
everything right.
Webers are not cheap, and the initial cost is just the "entry fee".
But they look so koool. And I'm Sick. (Hi Don S.)
rml
TR6's
With Weber DCOE 40's
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