mid mount weber

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 29 Mar 2004, 7:09 pm

#154131

My car has a 1916cc motor and Im running a mid mount 40 dcn weber. Is this carb ok to run my engine? Ive been having a lot of trouble with the car stumbling on acceleration and then she picks up. Ive put 33mm chokes in it and changed the jets accordingly. but also when she warms up blip the throttle and she stalls. rich?? I live in Brisbane and was told I dont need to "preheat the manifold, it doesnt get cold enough here". I would love to put duel carbies on it but thats down the track when I can afford it. So has anyone run this carb on a bigger motor successfully?

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 29 Mar 2004, 9:23 pm

#154230

"Ive put 33mm chokes in it and changed the jets accordingly."

and what would they be?? Sorry - tell us what jets they are

Single's can work - but rarely.

I wouldnt worry about the preheats.

The stalling could be the idle jet is too lean or the accelerator pump is not set right.

Futue te ipsum!!!

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 29 Mar 2004, 10:09 pm

#154271

I think they are 145 mains and 50 idles. so you think I might have to put up with it running like a dog till I can buy twins? is there any other alternative?

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 30 Mar 2004, 8:35 am

#154415

50 idle seems small for a single set up

Does it dial in at this??

Do you find "best lean" at 1 -2 turns out???

Futue te ipsum!!!

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 30 Mar 2004, 5:29 pm

#154671

dial in? do you mean the air mixture screws? The right hand mixture screw does nothing. wind it in or out all the way and the idle doesnt change. left one seems ok. could this be some of the problem?

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 30 Mar 2004, 6:16 pm

#154699

Sounds like you have a blocked jet or plugged circuit.

Should really "dial in" - especially as a single. ie one barrel feeding 2 pots.

That would cause a flat spot

Futue te ipsum!!!

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 30 Mar 2004, 6:36 pm

#154714

Ive taken out the right hand idle jet on the side the jet isnt blocked and Ive sprayed carb cleaner in the hole. the cleaner squirts out of the main jet so I guess its not bloked. Should the carb come off and be professionaly cleaned do you think? thanks for the help by the way.

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 30 Mar 2004, 6:44 pm

#154722

If the jet isnt blocked and cleaner is going through then it aint plugged.

The only thing i can think of is the air by pass screws are out of wack or the shaft is bent and the butterfly's are at different openings
The air by passes both need to be shut and only adjusted to compensate for minor differences in the butterflys.

Can you put a "snail" on and measure any fifference between the barrels

Futue te ipsum!!!

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 30 Mar 2004, 8:29 pm

#154786

"snail" ? whats that? and barrels as in left bank of cylinders and right bank? please excuse my ignorance

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 30 Mar 2004, 10:07 pm

#154840

a snail is a "syncrometer"

a device for measuring the air being sucked through the barrels of the carb

http://www.aircooled.net/new-bin/viewproductdetail.php?keyword2=TZE0021&cartid=0330200462617739

In a single dual barrel carb the leht barrel feeds cylinders 1 and 2

Right barrel feeds 3 and 4

The should suck at the same velocity. This is more important in twin dual barrel set ups.

But in your case something is wrong - and the 2 barrels should read the same as they are on a common shaft. If it is bent or the air bypass is badly adjusted this COULD be the problem

Futue te ipsum!!!

cumonghia Commited Dubber

70 posts · joined Mar 2004 · 1 Apr 2004, 6:09 pm

#155267

Thankyou thats great info. I will check these things and let you know. With the mid mount 40dcn operating and jetted properly, will she run and perform ok?

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 · 1 Apr 2004, 8:57 pm

#155318

Better than a solex.

Byronbug or one of the Nth Coast girls i "believe" has a single DCNF

Save for a set of Webers.
You will really notice the difference then

Futue te ipsum!!!

vassy66T1 Wow ... are U reading this?

2,120 posts · joined Jun 2003 · 4 Apr 2004, 7:01 pm

#156426

I have used a 40dcn on a 1776 and it ran just fine. I would start with 55 idle jets. I only had either 30 or 32 mm venturis and the 55 idle was the go. Sounds like a lean problem to me.
The accelerator pump could also be a problem area(ie, not enough fuel when you stab the throttle)
The other thing that needs to be spot on is the timing. Mine liked as much advance as you could dial in before pre-igniting.
The 1776 went great with it. That said, when I put a pair of 36idf carbs on, the improvement was outstanding.
cheers
Marcus
PS. I am in Brisvegas and have a unisyn to balance the carbs. E-mail me if you still need some help. vassy@coolcats.net.au

[Edited on 4-4-2004 by vassy66T1]

[Edited on 4-4-2004 by vassy66T1]

dubcab Seriously Crusin Dubber

175 posts · joined Sep 2002 · 4 Apr 2004, 8:22 pm

#156479

I ran my warm 1835 with a single 40 dcnf and it went real well. No stalling or hesitation at any rev point. I cant see a reason to change this carb for my new 1835. Would only swap for E.F.I. now.

dubcab Seriously Crusin Dubber

175 posts · joined Sep 2002 · 4 Apr 2004, 8:23 pm

#156480

I ran my warm 1835 with a single 40 dcnf and it went real well. No stalling or hesitation at any rev point. I cant see a reason to change this carb for my new 1835. Would only swap for E.F.I. now.