Subject: [TR] TR250 Weber Carbs

From: david brady <[email-masked]>
Date: Mon, 11 May 2015 14:22:59 -0400

Folks,

After lots of procrastinating I finally buckled down to understand and 
tune my triple webers. I had a bad case of the dreaded flat spot in the 
2K to 3K rpm range. If I could nurse it to 3K she sung like an opera 
star to redline, but in that 2K to 3K range any real amount of throttle 
and the engine virtually stalled; It just fell on it's face.

I joined Keith Franck's yahoo groups forum: sidedraft_central and 
quickly read every file in his Files repository and all the archived 
threads on the dreaded flat spot. I learned that the F11 is really a 
pretty horrible emulsion tube for the DCOE family of carbs. Keith 
recommended the F7 and it completely cured my flat spot. I can now idle 
the car in fourth gear, floor it, and it pulls strongly and without 
hesitation all the way to redline. Keith actually makes his own emulsion 
tubes but his modified design is very close to the F7. He simple said by 
adding a single anti-syphoning hole to the F7 I pretty much have one if 
his custom emulsion tubes.

Here's what I'm running:

Weber 40 DCOE 151's, Triple,
Choke: 30mm
Idle: 65F8
Air Corrector: 145
E-Tubes: F7 (modified with anti-syphon hole)
Mains: 125
Aceel Pump: 40
Aux Venturi: 4.5

The engine is dyno-ed at 150hp to the rear wheels. It has pretty 
extensive intake and exhaust porting and intake runner matching. I'm 
running an Elgin 715-18 cam, which has 240 degrees of duration at 0.050 
lift. I'm running 1.65:1 roller rockers for a total valve lift of 0.5". 
It has all the other goodies you'd expect: tubular pushrods, cam 
bearings, timing wheel, lightened flywheel, shaved head (9.5:1 
compression), 6-2-1 exhaust header, mechanical advance dizzy set to 28 
deg advance, ARP hardware, titanium keepers, hardened valve seats, etc.

David Brady
'68 TR250 CD8124L

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