Sorry gang
Second point about Mark Jones running a smaller carb then William Wynne
recommends.
Carbs are rated in their ability to breath typically in CFM or
cubic feet per minute. Using a smaller carb does NOT hurt and engine, merely
acts like a governor in that it limits the engines ability to perform to its
peak ability if it is matched to below what the total capability to perform is.
If you take the CID of the engine and apply it to a formula in the auto
mathbook, max rpm X displacement divided by 3456 (a constant) and then
multiply that answer by .85, you will get an approximate size of CFM carb that
will work for your application. If this puts you between 2 sizes, say a 600cfm
& a 650cfm, choose the 600. It will deliver better overall performance, and
use. The only time you should max the carb to engine is in race applications
when you will be operating at the upper end of the rpm range most if not all
the time. Mark Jones simply chose the next smaller Ellison and will probably
never regret it due to the fact that he will never be in the situation where he
will max out the capability of his engine. You are always better to choose 1
size smaller carb than 1 size bigger. The suction or vacuum signal received by
the carb is so much better, it virtually eliminates all operation complaints
that large carb users typically have, i.e.: stumble, hesitation, difficulty
setting mixture, varying idle, stalling, surging, coughing when accelerating,
loss of power at full throttle, unpredictable fuel consumption, plug fouling,
and premature engine wear due to cylinder wash.
Colin & Bev Rainey
KR2(td) N96TA
Sanford, FL
[email protected]
or [email protected]
http://kr-builder.org/Colin/index.html
