WEBER 28/36 Info Source Request
Bug
Weber 28/36 DCD carb.
Im trying to find any info, settings data / schematics etc for this
carb. Any help would be appreciated.
TIA
Mike
Tanuki the Raccoon-dog
<Captain.Blatstar@spam.?.net> said
Get yourself a copy of the Haynes "Weber carburettors" manual.
It's got a stripdown/rebuild sequence, plus sample jetting
info in the back, largely for things like Ford 105E Anglias/Mk.1
Cortinas.
Bug
Tanuki the Raccoon-dog <Tanuki@canis-^Hmajor.da^Hemon.co.uk> wrote in
message news:9t3BgAAS...@canismajor.demon.co.uk...
Oooo, sounds promising
Ta vewy much.
Sample jetting info too. I hope it has Imps in there as well.
Burgerman, John Williamson
"Bug" <Captain.Blatstar@spam@virgin.net> wrote in message
news:UyBF5.252$oD....@news6-win.server.ntlworld.com...
> A little help please?
> Weber 28/36 DCD carb.
> Im trying to find any info, settings data / schematics etc for this
> carb. Any help would be appreciated.
> TIA
> Mike
>
Weber carbs are easy....
On each barrel the following jetting/setting applies.
First you need a dyno/gas analyser......
Then set up the following. And I suggest you print this and take it with you
to get your car set up, as from my experience of some of them they are
clueless, although not all.
Main Jet (actually sized in mm so a 175 is 1.75mm diameter so you can buy a
set of drills...) works from around half throttle onwards.
It comes into play earlier if the float height is set higher, and later if
set lower.
Set it too high and fuel will dribble through the main circuit even at idle!
Also the Main jet works in conjunction with the Main Air Corrector. If at
wide open throttle and high rpm it is rich, but at wide open throttle low
rpm it is weak, you need a Bigger Main Air Corrector jet. And the opposite
is true. Full throttle CO level should be around 4 to 5 percent but varies
with different motors. Go for the CO that gives the most power on the dyno,
but a fraction on the rich side of ideal for safety and cooling reasons.
Accelerator pump jets are also available in lots of sizes. Use the one that
does not give any hesitation when the throttle is blipped and let go from
idle. Too small and it can flash back through the carb or pick up slowly or
cut out for an instant when you accelerate or blip the throttle. Too big and
when you blip it it will pick up and 'stall' when you let go as it will be
momentarily rich at idle.
Idle mixture is controlled by idle mixture screw. Set for smoothest idle
possible.
Idle jets control mixture just off idle, and transition/cruise. If these are
swapped, then the actual idle mixture needs resetting by the adjusting
screw.
Idle air correctors are not always adjustable on all Weber carbs, but they
control mixture with throttle closed or almost closed as at high rpm they
allow more air to emulsify the fuel. They are usually a little big on
purpose for emissions reasons, and cause popping and banging on open
freeflowing exhausts due to the weak mixture on overrun. If you block them
off on race engines you can get flames from the exhaust on overrun due to
the very rich closed throttle high rpm that you get! (my bike used to do
this..)
That just about covers how to set up any dellorto/weber type sidedraft or
downdraft, single or double barrel carbs. CV carbs (constant
velocity/constant vacuum) like most big bike carbs, some ford (VV) etc and
SU/Stromberg carbs work differently.
Hope that lot helps loads of you!
--
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Tanuki the Raccoon-dog
<Captain.Blatstar@spam.?.net> said
>
>Tanuki the Raccoon-dog <Tanuki@canis-^Hmajor.da^Hemon.co.uk> wrote in
>message news:9t3BgAAS...@canismajor.demon.co.uk...
>> In <UyBF5.252$oD....@news6-win.server.ntlworld.com>, Bug
>> <Captain.Blatstar@spam.?.net> said
>> >Weber 28/36 DCD carb.
>> >Im trying to find any info, settings data / schematics etc for this
>> >carb. Any help would be appreciated.
>>
>> It's got a stripdown/rebuild sequence, plus sample jetting
>> info in the back, largely for things like Ford 105E Anglias/Mk.1
>> Cortinas.
>
>Oooo, sounds promising
>Ta vewy much.
>Sample jetting info too. I hope it has Imps in there as well.
I just checked my copy. Alas there's no sample jetting for an
Imp. Seems odd to me that you're looking at a 28/36 on an Imp;
all the Imp motors i've seen have used either twin Strombergs
or in some of the hotter implementations, sidedraught Webers.
Bug
> I just checked my copy. Alas there's no sample jetting for an
> Imp. Seems odd to me that you're looking at a 28/36 on an Imp;
> all the Imp motors i've seen have used either twin Strombergs
> or in some of the hotter implementations, sidedraught Webers.
It seemed a little odd to me as well.
However, this carb has been inherited, ie came with the car. The usual
comments from vendor, *yeah, runs fine Mr, just been standing a while
thats all*. But he seemed an honest enuf type.
I have heard of the 28/36 on Imps before but as you observe, the usual
modification is sidedraughts or twin strombergs.
Perhaps these were the better carb or more suitable for a tuned[1]
engine, I know not.
What I do know is it ticks over horridly and wont take any choke at all
without flooding and dying, so its spanner time this weekend, bonus, it
gets me outa doing the shopping.
[1] I dunno!!! I have only v-recently acquired the car, definitely some
kind of comp dizzy (advance is???), 28/36 weber, 4-2-1 and straight thru
baffle. Cam & head work unknown as of today, maybe I'll poke around
there tomorrow.
Bug
Burgerman, John Williamson <burg...@ntlworld.com> wrote in message
news:W5EF5.681$NQ4....@news2-win.server.ntlworld.com...
>
>
> "Bug" <Captain.Blatstar@spam@virgin.net> wrote in message
> news:UyBF5.252$oD....@news6-win.server.ntlworld.com...
> > Weber 28/36 DCD carb.
>
> Weber carbs are easy....
<snipped loadsa helpful content>
>
> Hope that lot helps loads of you!
So do I !!
Thanks for the reply John.
Its coming off tomorrow so I'll be checking settings / jet sizes then.
I did think it was a bit of big carb for a throbbing 875cc s of pure
power (?) opinions anyone?
Dave Plowman
Haven't you missed out how to adjust the progression - the most difficult
part for a road car?
--
* Always borrow money from pessimists - they don't expect it back *
Dave Plowman dave....@argonet.co.uk London SW 12
RIP Acorn
Burgerman, John Williamson
"Dave Plowman" <dave....@argonet.co.uk> wrote in message
news:4a0cf0e437...@argonet.co.uk...
Depends what you mean by progression, if you mean from idle jets to main jet
transition it is controlled by tiny holes drilled in the carb body right
where the throttle plate closes and in most production cars this is not
exactly adjustable.
Is this what you are referring to?
Or venturi insert sizes?
Or emulsion tubes?
Give me some idea what you are referring to.
Dave Plowman
"Burgerman, John Williamson" <burg...@ntlworld.com> wrote:
> Depends what you mean by progression, if you mean from idle jets to main
> jet transition it is controlled by tiny holes drilled in the carb body
> right where the throttle plate closes and in most production cars this
> is not exactly adjustable.
Yes. It *is* adjustable after a fashion by either enlarging the holes or
drilling holes in the butterfly. That's why I said it was a pig. And it
affects the running of the engine over quite a wide band at slow cruise.
--
* Who is this General Failure chap anyway - and why is he reading my HD? *
Burgerman, John Williamson
"Dave Plowman" <dave....@argonet.co.uk> wrote in message
news:4a0d04d5ae...@argonet.co.uk...
The effect can be covered to a degree by the amount of overlap that all the
different circuits have, and all of these are reversible (jetting) So
altering these holes in the bore whilst possible is not exactly easy to do,
or to improve on. So I chose to ignore it for the purpose of this post, as
it is a little involved.
But if you wish to add the bit I ignored, then feel free!--
Visit my personal website for movies, pics (of my nurse!) , miniature jet
engines, DDA act, VR6 MPV, Bikes, Nitrous V8 Sierra, Tuned Powerchairs and
Dave Plowman
"Burgerman, John Williamson" <burg...@ntlworld.com> wrote:
> But if you wish to add the bit I ignored, then feel free!--
No - I failed miserably trying to get smooth progression on a mildly tuned
MGB fitted with a 45 DCOE. Went back to SUs as it was a pig to drive in
town. But plenty of power on a rolling road.
--
* A snooze button is a poor substitute for no alarm clock at all *
Uptodate
>
> A little help please?
> Weber 28/36 DCD carb.
> carb. Any help would be appreciated.
> Mike
Take a look in David Vizard's 'Tuning BL's A-Series Engine'
david halley
standard with the twin Strombergs. Took them off and put 28/36 on. Made a
major difference to driveability with a little extra power. The two chokes
open sequentially so you get the benefits of a smallish single choke up to
half throttle and then the benefits of twin choke thereafter.
Major problem on these carbs is wear in the carb body allowing the throttle
spindle to wobble about and let air in through the spindle holes. A weber
specaialist will be able to bore and fit bushes.
As you don't know the state of tune of the rest of the engine, a rolling
road is gouing to be the only truly accurate method of tuning.
Have fun
David
Martin Eva
What he does not know about carbs is not worth knowing
tell him the exact details of engine, carb current specs etc and he will
offer advice
Regards
Martin
Uptodate <upto...@chello.nl> wrote in message
news:39E832A7...@chello.nl...
Bug
> In article <vyMF5.1897$NQ4....@news2-win.server.ntlworld.com>,
> "Burgerman, John Williamson" <burg...@ntlworld.com> wrote:
> > But if you wish to add the bit I ignored, then feel free!--
>
> No - I failed miserably trying to get smooth progression on a mildly
tuned
> MGB fitted with a 45 DCOE. Went back to SUs as it was a pig to drive
in
> town. But plenty of power on a rolling road.
>
"holeless" Im more interesting in getting a smooth running tractable
engine than ultimate BHP. Thanks.
Bug
david halley <david....@ntlworld.com> wrote in message
news:DH3G5.3616$oD.7...@news6-win.server.ntlworld.com...
> Going back into the mists of time I had a Sunbeam Stilletto which came
as
> standard with the twin Strombergs. Took them off and put 28/36 on.
Made a
> major difference to driveability with a little extra power. The two
chokes
> open sequentially so you get the benefits of a smallish single choke
up to
> half throttle and then the benefits of twin choke thereafter.
>
> Major problem on these carbs is wear in the carb body allowing the
throttle
> spindle to wobble about and let air in through the spindle holes. A
weber
> specaialist will be able to bore and fit bushes.
Im not in this state just yet, I've tried (gently) moving the
butterflies and I cant detect any movement other than that in the usual
direction of rotation.
> As you don't know the state of tune of the rest of the engine, a
rolling
> road is gouing to be the only truly accurate method of tuning.
Yes, as others have also suggested, this would seem to be the best way
forward. (Any near South Leicestershire that folks would recommend).
> Have fun
I do try!!
However, the electric fan controller (black box) has died!! Grrrrr,
Arghhh. This needs sorting pretty pronto so as not to become a potential
source of head warp. Ho hum, off to Kenlowe.com...
Mike
Burgerman, John Williamson
"Bug" <Captain.Blatstar@spam@virgin.net> wrote in message
news:4_yG5.6608$oD.1...@news6-win.server.ntlworld.com...
>
> Dave Plowman <dave....@argonet.co.uk> wrote in message
> news:4a0d123ffa...@argonet.co.uk...
> > In article <vyMF5.1897$NQ4....@news2-win.server.ntlworld.com>,
> > "Burgerman, John Williamson" <burg...@ntlworld.com> wrote:
> > > But if you wish to add the bit I ignored, then feel free!--
> >
> > No - I failed miserably trying to get smooth progression on a mildly
> tuned
> > MGB fitted with a 45 DCOE. Went back to SUs as it was a pig to drive
> in
> > town. But plenty of power on a rolling road.
> >
> Interesting reading but I think I'm gonna be leaving the butterfly
> "holeless" Im more interesting in getting a smooth running tractable
> engine than ultimate BHP. Thanks.
>
???? modifying the progression holes and drilling small holes in the
butterfly is usually a desperate attempt at trying to get smooth progression
from idle to 'just off idle' and I have never found a need to do it. The
other jets allow enough control of this. And it makes no difference at all
above say 1/8th throttle anyway.
So what does it have to do with "ultimate horsepower"?
Capt Blat
Burgerman, John Williamson <burg...@ntlworld.com> wrote in message
news:bHCG5.6836$oD.1...@news6-win.server.ntlworld.com...
>
<snipped content>
>
> ???? modifying the progression holes and drilling small holes in the
progression
> from idle to 'just off idle' and I have never found a need to do it.
The
> other jets allow enough control of this. And it makes no difference at
all
> above say 1/8th throttle anyway.
>
> So what does it have to do with "ultimate horsepower"?
>
Better actually *READ* and absorb before I post next time..
:-)
Mike
Gareth Smith
Try looking at this web-page:
http://users.bart.nl/~franka/tech/carbs.html#Weber
has 28/36 settings for 875 and the 998 using a 28/36. Also try the
"imps" group on egroups (www.egroups.com). A lot of Impers hang out
there and a fair few engine builders answer the queries, well we all
contribute.
Cheers
GarethS
Gareth Smith
> Im more interesting in getting a smooth running tractable
> engine than ultimate BHP. Thanks.
if you are not running better than an L4 head you don't want more than
twin Strommies. The 28/36 apparantly does not give smooth power. Oh and
make sure you are running a heated inlet manifold if you are running
better than a Solex (one guy on the Imp mailing list would tell you to
*always* use a heated manifold).
HTH
GarethS
Jim Warren
Tanuki the Raccoon-dog <Tanuki@canis-^Hmajor.da^Hemon.co.uk> wrote in
message news:Xyd7HCA6...@canismajor.demon.co.uk...
> <Captain.Blatstar@spam.?.net> said
<snip>
> all the Imp motors i've seen have used either twin Strombergs
> or in some of the hotter implementations, sidedraught Webers.
The original Imp had a Solex, I believe.
Twin Strombergs were fitted as standard to the Imp Sport and Sunbeam
Stiletto.
Gareth Smith
> The original Imp had a Solex, I believe.
> Twin Strombergs were fitted as standard to the Imp Sport and Sunbeam
> Stiletto.
some) on their fast road and race motors. Other carbs have been tried
allong with Nikkis and Fische carbs. One guy I know wants to try four
motorbike carbs.
Capt Blat
Gareth Smith <me9...@brunel.ac.uk> wrote in message
news:39ECD3DC...@brunel.ac.uk...
>
> If you want smooth tractable power go back to the twin Stromberg 125s,
> if you are not running better than an L4 head you don't want more than
> twin Strommies. The 28/36 apparantly does not give smooth power. Oh
and
> make sure you are running a heated inlet manifold if you are running
> better than a Solex (one guy on the Imp mailing list would tell you to
> *always* use a heated manifold).
> HTH
> GarethS
I think I will be keeping the 28/36, I had a tinker over the weekend and
I now have a reliable and steady tickover at 900rpm. I also changed the
coil as the old one was only providing a yellow spark, this along with
using the correct Champion RN9YC plugs, I suspect, has helped a lot as
well.
Im curious as to the *always use a heated manifold* reference.
Mine isnt heated, there is provision for the plumbing but its not
connected.
I thought that having colder and therefore denser air in the inlet
charge would be better than having a warmer inlet charge.
The only 2 reasons I can think of at the moment for having a heated
manifold are;
A/ To aid vapourisation of the petrol
B/ To prevent carb icing (is this likely to be a problem in dear old
Blighty???)
Is the trade of better fuel vapourisation instead of a denser air
mixture the preferred way to go on an Imp, or any engine for that
matter? Comments please anyone.
Capt Blat
I've had a look at that page, it is certainly a credit to the author,
very useful and informative reading all round for anything Imp related.
BTW those Ginetta G15's do look *very* tempting.
Capt Blat
>
> > The original Imp had a Solex, I believe.
> > Twin Strombergs were fitted as standard to the Imp Sport and Sunbeam
> > Stiletto.
on
> some) on their fast road and race motors. Other carbs have been tried
> allong with Nikkis and Fische carbs. One guy I know wants to try four
> motorbike carbs.
Nice idea. I just happen to have four serviceable carbs of a VF750 and a
couple of spare 875cc engines (in lots of bits).
;-)
Capt Blat
> > Is the trade of better fuel vapourisation instead of a denser air
> > mixture the preferred way to go on an Imp, or any engine for that
> > matter? Comments please anyone.
> >
the
> Implist who have used heated manifolds with an after market carb say
they
> are much better at starting first thing in the morning.
>
> Interesting to see someone using Champion plugs, personally I stick
with NGK
> BP6ES (or is it SE?), they seem better able to tolerate higher revs
(which
> is what an Imp engine is all about). For the 930 I'm building I'll go
to
> cooler NGK BP7's .
>
Generally I find the NGK plugs to be superior to any other make I have
tried (Bosch, Champion, Denso + others I cant remember), I also use them
in the bike as well and have never had cause to complain.
However, due to the difficulties I've been having I decided to opt for
as close to original spec equipment as possible (I do suspect the rest
of the engine is hardly in its original format, so maybe it was a daft
decision) and it seems to be responding well.
Small point of note, I was suffering a little carbon fouling on the NGKs
which doesnt appear on the Champion plugs, perhaps the Champions are
just a gnats hotter grade of plug?
Ps, do please check your NGK codes, whether the 7 is cooler than the 6
or not??
I have conflicting information and would like to be sure which is
correct.
Mike
Tanuki the Raccoon-dog
<Captain.Blatstar@spam.?.net> said
>Ps, do please check your NGK codes, whether the 7 is cooler than the 6
>or not??
>I have conflicting information and would like to be sure which is
>correct.
With Champion, the higher the number, the hotter the plug (so, for
example, a N12Y will run hotter than a N9Y, with a N7Y being even
cooler)
NGK ones are the other way round - high numbers mean cooler plugs.
R. N. Robinson
>
> > The original Imp had a Solex, I believe.
> > Twin Strombergs were fitted as standard to the Imp Sport and Sunbeam
> > Stiletto.
> some) on their fast road and race motors. Other carbs have been tried
> allong with Nikkis and Fische carbs. One guy I know wants to try four
> motorbike carbs.
I put 4 Amal Monoblocs on an Imp more years ago than I care to remember.
Made the mistake of using bicycle spokes to raise and lower the slides and
they quickly fell victim to the vibration period that Imp engines tend to
suffer from - well that one did anyway. Around 4000 and 8000 rpm IIRC.
Apart from that they worked very well, but for road use the inch and a
quarter SU's from a Spitfire (?) were the best bet. This was with a
60,30,30,60 or thereabouts cam. You make your own manifolds of course - its
great fun, especially the 4-2-1 exhaust part of it.
Ron Robinson
Gareth Smith
Gareth Smith
> very useful and informative reading all round for anything Imp related.
> BTW those Ginetta G15's do look *very* tempting.
>
car.
Gareth Smith
> or not??
> I have conflicting information and would like to be sure which is
> correct.
number, more expensive the plug).
As for OE I'm sure I have written down that old BP6Es were OE, they didn't
have copper cores in those days (what the S is for I think).
Gareth Smith
> I put 4 Amal Monoblocs on an Imp more years ago than I care to remember.
> Made the mistake of using bicycle spokes to raise and lower the slides and
> they quickly fell victim to the vibration period that Imp engines tend to
> suffer from - well that one did anyway.
but nearish the 60mph mark) then go quite for approx 5 to 10 mph, then start
being noisy again. Anyway back to the Amals, can you send me any info
off-mail-group as I have a mate who might be interested.
> Apart from that they worked very well, but for road use the inch and a
> quarter SU's from a Spitfire (?) were the best bet. This was with a
> 60,30,30,60 or thereabouts cam. You make your own manifolds of course - >
its great fun, especially the 4-2-1 exhaust part of it.
One of the guys on the list swears by a pair of 1.25 SUs, tried everything
but they are apparantly the best (and underrated according to him). Any
info on making the inlet manifolds would be useful as I am hoping to get the
flow right on the head before adjusting anything else. The exhaust system
is a custom and has already been flowbenched by the builder (minimal mods
needed as it is based around m/bike exhausts he builds).
Cheers
GarethS
Paul Adamson
constant noise, just every now and then. Its like, "there it is, no its
gone". "there it is again, and gone again". I think it goes away when the
engine is warm, but im not sure. I only notice it when i start it up, as i
have my stereo on after that... its not very loud, really faint, but just a
bit annoying. Could it be an air leak?
Anyone any ideas?
Regards
Paul Adamson
Paul Adamson
Jim Warren
My local spares shop supplied me with NGK BPR6ES as an equivalent of
Champion N9Y and I've been very happy with them. Not sure what the
significance of the R is though. ISTR same supplier also sold me BP6E some
time ago for a different car.
>
Gareth Smith
> Champion N9Y and I've been very happy with them. Not sure what the
> significance of the R is though. ISTR same supplier also sold me BP6E some
> time ago for a different car.
in-car stereo etc. For some reason I haven't damped any of my electrics yet
I get no interference on the stereo
Burgerman, John Williamson
"Jim Warren" <jimw...@freeuk.com> wrote in message
news:CiwH5.590$IF1....@nnrp3.clara.net...
r = resistor
--
Visit my personal website for movies, pics (of my nurse!) , miniature jet
engines, DDA act, VR6 MPV Disabled converted van, Bikes, V8 powered Ford
Sierra with Nitrous!, Tuned Powerchairs and more!
http://www.dynopower.freeserve.co.uk/homepages/
http://www.john-c-williamson.co.uk/ (mirror, slower sometimes)
email burg...@ntlworld.com
R. N. Robinson
Sorry, going to reply to the group - there might be someone else interested.
Unlikely, but that's what its all about after all.
As I said, it was a very long time ago. IIRC they were 1" Amal Monoblocs
but I cannot remember jet sizes or anything else. My advice to anyone
thinking of doing the same thing is - don't. A small part of the reason why
not is the throttle linkage which either has to be a vibration-proof solid
push-pull to the slides or working them with cables, in which case each carb
will have to have its own spring. This will result in a very heavy
accelerator pedal, the only way out of which is to incorporate a throttle
opening spring at the engine end. Don't laugh, we did it on a Formula
Junior car which was presented to the scrutineers every week-end all through
a whole season - they all checked the spring, none of them twigged it worked
the wrong way! If you really need one choke per cylinder then I reckon
Webers (35DCOE?) are the way to go.
I can't remember a lot about the SU's either, but I think I made a rake type
manifold, i.e. a tube (1.25"or so) parallel to the engine axis with short
straight tubes connecting to the inlet ports and other larger ones to the
carbs. This had the advantage that all the tubes could be straight and
constant diameter. Curved tapered tubes are not the easiest things in the
world to make.
Ron Robinson