Gerald F. Doherty wrote:
>
> I'm new to this list, so I hope this isn't something that has been
> previously discussed (although I would be shocked if it wasn't).
>
> I'm contemplating an engine rebuild for my 73 TR6. I asaked me mechanic
> for suggestions on increasing the horses. He strongly urges installation
> of triple Webers, although he says they are sometimes hard to keep in
> tune. He also indicated that the car would probably idle rougher with
> the Webers.
>
> I do not compete in the car; its just my favorite toy. I'd appreciate
> any advice anyone may have on installing Webers, or hearing any
> experiences (good or bad) anyone has had with them.
>
Jerry,
About 5 years ago, I installed twin side-draft 40DCOEs on my basically
unmodified (just 50 thou off the head) 1500 engine. The engine has since
been modified to take advantage of the extra induction.
I did the jetting myself, basically following the suggestions in the
books. Over the period of about a year, I was on almost a first name
basis with the folks a Pierce Manifold, buying a jet either a little
larger or a little smaller than what I had on hand. I now have a rather
good collection of idle, main, and air correction jets.
The car now runs very well with the same jet settings I finalized about 3
years ago. What really helped dial in the mixture adjustments was the
installation of an in-dash air/fuel mixture gauge. It allows you to
monitor the mixture at idle, progression, and full bore. The only
adjustment I make now is with the idle speed, to compensate for cooler
and denser, or warmer and thinner air that comes with the change of
seasons.
What I'm getting to here is, if you install these carbs, be prepared to
either sort them out yourself, or have someone near at hand who can.
Lumpy idle? Yes, maybe, but only because each piston basically has it's
own carb. That makes each intake port more sensitive than two carbs that
supply all six cylinders. Slight imbalances with the idle mixture or idle
speed screws need to be corrected for a smooth idle.
An engine, running at any speed, or under any load can only use so much
fuel--too much and you're running rich, to little and you're running
lean. The great thing about Webers is they are almost infinitely
adjustable. I was able to properly jet the carbs for stock and modified
engines. They will give you a boost in performance, stock or modified,
but only it they're set up properly.
Would I go back to SUs or Strombergs on my autocross car? Hell no! I like
standing on the go pedal and getting immediate response.
'nuff said,
Charlie B.
Spitfire Pilot
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