twin carbs
donn - July 7th, 2011 at 10:30 AM
Ok, as some of you know I'm about as clued up on this stuff as my 3 year old grandson, so bear with me, after the Bugs and Busses by the Bay outing
last week I am back on the idea of twin carbs on the buggy (thanks Mick and Scott and a few other fellas there) long time ago I had been told that
there was no room under the back of the wench to fit the twins so I had discounted the idea but the fellas there pointed out that if I used Type 3
inlet manifolds then I can fit the twins, from there there was several sugestions regarding the type of carbs to use but I have since been wondering
why I don't just fit a pair of Pict32's (or whatever), so now I need you fellas to tell me why not. 
donn - July 9th, 2011 at 10:24 AM
Too hard ?
Bizarre - July 9th, 2011 at 11:27 AM
Why??
If it is street use - twins are ok
I "believe" twins are not the go for off road use??
Too much slosh is what I have heard
I know you can get stubby Type 3 manifolds for IDF Webers but all up I doubt you will have change form a grand
As for the 32's - I think it is a case of too old, no gain, too much to rebuild
Guess it comes back to why
Post a pick of the rear of the buggy
matberry - July 9th, 2011 at 03:07 PM
Why would duals slosh more than a single off road?? Slosh issues comes down to the type of carb. I'd say it's mainly to do with hassle of linkages
in the dirt and grime and air filter location is bad news with any dual carb off the shelf system. Use awesome an air filter system and/or remote
mount the filter into clean air and no problem.
As for the 32's, same answer, why? go Kadrons as the first step, IDF's as prefered IMO.
Bizarre - July 9th, 2011 at 04:31 PM
| Quote: |
Originally
posted by matberry
Why would duals slosh more than a single off road?? .
|
Just from my readings at AC.net and other places
I have no experience at bajas and the like
here is an exanple......................
OFF ROAD APPLICATIONS
90% of the time, off road applications should use a centermount system. Why? There are a couple reasons. The first is simplicity. Dual carbs require
more complex linkage, and when you are talking about off-road use, this is just more parts to break or give you problems. In addition to this, dual
carbs are mounted on the outside of the car, where they are vulnerable to getting hit with debris. Lastly, a carburetor mounted in the center is going
to get bounced around less then if it's mounted on the outside of the car as the car is pitched side to side. Therefore, fuel control is easier (less
chance of flooding) with a centermounted carb. The power difference between a centermount and dual set-up is very small, and with the above noted
advantages of running a single, it's an easy decision to justify. If you want corroboration, just have a look at the winners of the SCORE races and
then check out the induction systems installed on the winning cars...
donn - July 9th, 2011 at 05:25 PM
Thanks for that, so far as I knew twins would give me a bit more low down and I thought maybe just use the standard carbs (pict 34, I wasn't too sure
what is on the motor now), after spending the afternoon with a couple of fellas with some knowledge of these things I have opted to stay single 34 as
it's for road use not off road and the engine is stock. It seems I may need a different air filter as the one that is on it may be too small, a few
other things to sort may make a difference. 
grumble - July 9th, 2011 at 07:31 PM
Fair decision Donn I have fitted and used a lot of twin setups over the years when I was a little younger, strombergs, nikki dual throats ,solex's,
webers and a few more,more often than not they took a lot of setting up for little return in regards to performance or economy with the associated
problems .As age and experience comes into the equation .We had a lot of great experiences with these but now I am running a single carb on the Ghia
and enjoying it a lot more than working on the side of the road Cheers Les
matberry - July 9th, 2011 at 09:02 PM
| Quote: |
Originally
posted by Bizarre
| Quote: | Originally
posted by matberry
Why would duals slosh more than a single off road?? .
|
Just from my readings at AC.net and other places
I have no experience at bajas and the like
here is an exanple......................
OFF ROAD APPLICATIONS
90% of the time, off road applications should use a centermount system. Why? There are a couple reasons. The first is simplicity. Dual carbs require
more complex linkage, and when you are talking about off-road use, this is just more parts to break or give you problems. In addition to this, dual
carbs are mounted on the outside of the car, where they are vulnerable to getting hit with debris. Lastly, a carburetor mounted in the center is going
to get bounced around less then if it's mounted on the outside of the car as the car is pitched side to side. Therefore, fuel control is easier (less
chance of flooding) with a centermounted carb. The power difference between a centermount and dual set-up is very small, and with the above noted
advantages of running a single, it's an easy decision to justify. If you want corroboration, just have a look at the winners of the SCORE races and
then check out the induction systems installed on the winning cars...
|
Mmmm interesting, many variables with that statement. Pitch center of the vehicle, type of bump encountered etc etc. Next sentence says there's
little difference between single and dual hp figures .... go figure ?
One thing I forgot to mention which is proberly the most important (a post above made mention of it), offroaders tend to build for torque and SINGLE
carb setup will have more bottom end torque than duals.
donn - July 10th, 2011 at 10:01 AM
Is there any advantage in using a different type of carb, ie, duel throat over single, solex over webber etc?
matberry - July 10th, 2011 at 11:16 AM
| Quote: |
Originally
posted by donn
Is there any advantage in using a different type of carb, ie, duel throat over single, solex over webber etc?
|
A lot depends on the exact engine combination, but in a nut shell, a single dual throat will definately outperform a single single throat in my
experience. A single DCN is ok, a Zenith 32 NDIX is better, for a small engine at least. They both have thier drawbacks though. The DCN suffers from
BAD flooding issues when at angles or cornering/braking etc, the Zenith is old and has an old style acc pump system that I could do without, but they
are really the best for smooth delivery at all times.
I'd go IDF , a 40 or even 36 for a small engine, and 1900 upwards a 44, esp with a mild cam and preferebly some head/chamber work (naturally 
)
ANY single NEEDS an effective manifold heating system to operate properly in all temperature conditions IMO.
donn - July 10th, 2011 at 04:03 PM
ANY single NEEDS an effective manifold heating system to operate properly in all temperature conditions IMO.
So there is one of my problems I believe, though I came to that conclusion some time back, my manifold has no provision for a preheat as is on the
engine I have waiting patiently for me to decide where to go with it (procrastination, the theif of time ) so looks like I'll have to chase down
another manifold unless there's onother way of heating it.
Bizarre - July 10th, 2011 at 04:40 PM
some people say the electric manifold blankets work
I am not one of them
matberry - July 10th, 2011 at 04:59 PM
The easiest option to try is to use warm carb intake air, ie a snorkel or pipe picking up used cooling air or a pickup near an exhaust port to the air
filter surround. VW did this from early on, and also had the manifold preheated with the exhaust. Problem is it all starts to look pretty ugly. And a
summer winter switch would be best....