No air bypass screw on early Weber 40's

[2002Scoob]

at least that's what I've always read.... but now that I think about it.. in theory I'm not sure it matters. If you pull the low-high, you'll have to drop the idle, and if you go high-low you might have to speed it up a bit. 

[Sharktrainer]

Throwing in the towel. One carb is untunable on one side of it. Gonna either try to find another old Weber DCOE2 or proceed finishing my parts round up on turbo setup. Have everything but still need to make the plenum and runners and order forged pistons to bring compression down.

 

My question is can I put the normal intake with 38/38 Weber on and leave the sidedraft coolant bypass kit on and not connect original coolant lines to said manifold? Again live in a hot environment so choke is irrelevant mostly. Does the coolant inside play some sort of role in atomization or..?

 

 

Edited July 4, 2017 by Sharktrainer

[2002Scoob]

how or why is it un-tunable? 

 

Twisted throttle shafts? Clogged passages? 

 

Both are easily solved. 

[Sharktrainer]

No change when I turn that fuel screw like the other 3. Spitting and backfiring out that mouth and exhaust on low circuit. Runs like a raped ape when you get past low rpm issues.

 

One of the mounting eyes was broken off on this area and broke right along where fuel screw goes. I repaired with JB Weld and it held but this is the area that can't be dialed in. Pretty sure I didn't plug the passage. When I crank it out crazy amount of turns, it shoots a flash of flame.

 

I've changed for obvious no reason after the fact the idle jets to 55f8 from a 55f2 and air corrector to 175 from a 200. Regulator set to 3.5.

Edited July 4, 2017 by Sharktrainer

[2002Scoob]

32 minutes ago, Sharktrainer said:

 

One of the mounting eyes was broken off on this area and broke right along where fuel screw goes. I repaired with JB Weld

 

Well there's your problem... That's a pretty big variable you introduced to us!  I vote Recycle bin. DCOE's are great things when set up properly, I've found. But little inconsistencies like # of progression holes and spacing, clogged passages, dirty jets, etc can lead to frustrating issues if you're just learning, let alone trying to tune out a crack extending into the idle/progression circuit passages. 

[TobyB]

Quote

My question is

• can I put the normal intake with 38/38 Weber on and leave the sidedraft coolant bypass kit on and not connect original coolant lines to said manifold?
• Does the coolant inside play some sort of role in atomization.?

Yes.  It'll work

Yes, it improves fuel vaporization by preventing fuel from condensing on the walls of the manifold.

 

Keep your busted carb as a parts carb, and hit ePay or such.  Single bodies do turn up from time to time.

 

t

 

[Sharktrainer]

Found the problem. Epoxy made its way to the tiny hole that goes into throat by butterfly of said shade tree repair. Trying to clear it now. 

[Sharktrainer]

Sorted, got it so close now and can adjust that side now,  but feel I should go with f16's emulsion tube for it to be tits instead of the f15's  in there now.

 

We both extend a big Mahalo for your help.

[TobyB]

See?  You CAN sometimes go wrong with JB Weld!  Glad you got it sorted, tho, and thanks for the followup!

 

t

 

[Simeon]

3 hours ago, TobyB said:

See?  You CAN sometimes go wrong with JB Weld!  Glad you got it sorted, tho, and thanks for the followup!

 

t

 

 

Should have used duct tape. 

[Sharktrainer]

I didn't just spooge JB on the broken tab, lol.

I drilled at a mean angle through the 2 broken pieces and with a tight fit put 2 stainless bolts through and then JB the two mating surfaces so seal airtight.

[2002Scoob]

Oh my..... 

 

Yep, definitely something that could be considered a factor when discussing getting DCOE's to work, haha.

 

+5 Macgyver points for you. 

[Sharktrainer]

Today my jets, emulsion and correctors finally arrived.

 

Ordered;

190 corrector

F16 emulsion

120 main

50F8 idle

 

Prior

170 corrector

F15 emulsion

125 main

55F2 idle

 

This is how I came up with the supposedly correct jetting (some random Weber site)

 

 

 

 

With the prior jetting, I was getting maybe 4-6 miles per gallon, but it had big kahunas. 

 

Installed the ordered jetting and it runs smoother, economy probably 12-15 miles per gallon, but it's not quite the savage as with old jetting. Notice it starts leaning out @4500 rpm whereas the old jetting didn't struggle when you pushed to redline, in fact got there in quite a hurry.

 

 

 

 

My question is which component should I change to maintain fuel economy, even 10 mpg is fine just as long as it has stab at upper rpm range.

 

My thought maybe one step on main jet? Go back to F15?

Or should I leave as be and turn the screws in some more?

 

 

 

Edited July 19, 2017 by Sharktrainer

[eurotrash]

Install an AFM and when you get it to hang in the 13-14.5 range, you'll get your best mileage to boot. 

 

www.wide-band.com

 

Edited July 20, 2017 by eurotrash

[TobyB]

Check your float levels a third time- a 120 main jet should get you over 12 mpg at the race track.

 

But what kills your fuel economy is the 'idle' jet, which is really a transition jet, and is doing most of

the fuelling when you're cruising below about 80 mph.

 

So try going smaller there, and you'll find you have to open the idle screw to compensate, at a certain point.

But you'll get notably better economy.

 

at 5 mpg, you're probably dumping raw fuel- which isn't good for anything.

 

I agree, the wideband is such an indispensable tool for Webers, I wouldn't go out to the garage without one.

 

t