Outer Limits 4x4 Board

Thought i might start a hread for just aisin carb tech, there re a few hints on mikuni and a whole 15page + for he weber.
If you are of the opinion that one should not bother and all efforts are hopeless (you may very well be right) ples save it from other threads

My carb is fine, but i am trying to get a second one rebuilt and running myself from a new engine that i am piecing together.

I am modding the intake at the same time by epoxy putting up all the stepped bumps and crevices into one continuos edge. i have used up about 10cc of dead space with putty just in the chamber below the throttle without decreasing passage holes. i took care not to cover vacuum holes but may not of been so careful with the egr and pcv passages..

i figured it will strengthen my vacuum signal and give the fuel/air only one direction to go. Sort of like the theory behind throttle spacer plates.

Anyway back to the carb, my choke died on my current carb the first time i flushed the radiator so i diconnected the spring thats kept it activated nd been running without it no problems.

so i have removed the choke completely and will block hole with a nut and bolt in case i fill like puttng a manual choke later or need it for some other squirelly idea.

i have been cleaning all the casting flash with a rotary tool (quite a bit) and am debating wether to cut the support arm off the venturi to increase flow.

The other idea is the jets, the ones i pulled out have the numbers 099 and 106 on them. after several days searching for size i got some info that weber primaries may fit and this link
http://dairally.net/daihard/chas/AisanC ... nJets.html
its good how hey went hrough the effort of listing the two throttle sizes of 28/32 and 30/34 and the venturi neck sizes.

What gets me is that although the primaries are around the same size as my suzuki for the various displacements the secondaries are on average 30% larger. Most appear pre pollution.

i was thinking maybe stepping the secondary 106 up to like a 113-115 or something nd keep an eye out for a 100- 101 that i could use on the primary, run a litle richer


comments, constructive critism or you own little secrets /isues/ ideas etc welcome.

from memory the toy carb 3k,4k runs a bit richer as well, also inc manual choke mech.

it also had a slightly bigger throat too.

maybe an option to play with

yes i think they are 30/34. if you enlargen the holes on the intake they might be a better starting point.

i already got a sierra carb and am trying to increase flow where possible whilst still keeping the overal diametre tight to help with air velocity/vacuum signals etc etc.

one of the other things i will be trying on the intake is the powerlynz like someone did on a 1l g10 in teamswift, he did it as a MPG mod and claims his sparkplugs stay shiny clean.



The idea is similar to the theory marketed by hiclone/tornado/vortex devices. Create turbulance to inrease the fuel and air mix. Loosing a litle cfm in exchange for a better mix and thereby a better/even/complee burn. i have to look celticshamans (on suzishop forum) explanation of why it does work and why it doesnt, it was really good.

Not going to do the head till i see if it makes any diferrence. but since an intke i so easy to replace why not. (anyone here can lend me a 1" thread tap?)

the other iea i am tossing up with is a fuel preheater. since i got spare hoses that was on the choke maybe route a hot water pipe one turn over over the fuel line going to the float. The idea is it gets the fuel temparature warmer so it atomises easier. Less is safer than more in this ide though cause if its to warm it will just boil in the float chamber. Again smethin that takes 3mns to bypass if you live in regular 40 degree plus weather.

forgot to add... are the secondary vacuum actuators on the small displacement motors (mighty boy, daihatsu handy etc) smaller diametre? if so maybe they require less vacuum and would let you activate them sooner on a 1.3l?

im running a corolla 4K carby and they are jetted larger than the sierra carb. it goes alot harder than the sierra carb and still gets ok economy. I like to tinker with my carbs so im interested in what your up to. If i get a chance over the next few days ill try to find out how the 4k carby is jetted.

B4T

the fuel/ air mixes just under the butterfly (brain fart and can't think of the name) from what i know.

then its about getting it into the back of the valves as quick and with as much air speed as you can then the back of the valves swirl it around again as it goes into the chamber

some updates,

had 30mins spare and i was in the area so i went to pick and payless

pulled two aisin carbs apart for the jets

92 993cc daihatsu charade = 083/141
88 1.6l =4a-c toyota corolla = 105/153

didint have time to ransack a swift g13ba carb but i noticed they are all electronic chokes rather than wax like the sierra. other than issues with deep water crossings it might be a good alternative to a manual choke.

stiill want to get a few more jets from a few similar displacement vehicles like 1.3l daihatsu/toyota/mazdas, sets from g13a and ba swifts and a set from a g10.

whats i dont understand is why the carb i am rebuilding has such a small 2nd jet, maybe its an accident or suzuki wanted an even metering down each barrel to avoid a huge surge of power as the secondaries roared to life

anyone got a dead ca4rb they can pull the jets from?

Just step away on the heating the fuel in the line santos ,

you.ll end up with a vapor lock in the carb there hard enough to find the cause when they happen let alone create one

Dozoor wrote:Just step away on the heating the fuel in the line santos ,

you.ll end up with a vapor lock in the carb there hard enough to find the cause when they happen let alone create one

yes i knew some parts of petrol had really low boiling points, i just didnt realise how much. One for the backburner and winter snow expeditions

i may have some bits round here from diff carbs. i'll have a look when next in parts section (shed)

just an update still no jets but i been playing around with the airbox hat, a IR themometer showed that the black hat was 33-38 degrees after an hours drive. ambient temps 17-22

i painted a spare one i had bling aluminium silver, same drive and it measured 21-25 over the last two night, ambient temp 16-19

10 degrees have by just changing it to colour that reflects the radiant heat, so my plan is to bling up the intake to reduce heat temps on the intake side, i dont want to much cold air as i want 100 vaporisation but not so hot it causes detonation and loss in air density

if your using a snorkel then air would be cooler as it is being forced into the air ram..

Reflective coatings on the air intake surfaces will lower heat absorbtion rates but i doubt it would do much to actual air temp entering the carby.

Now with air flow i found that when running the weber i had issues with air entering from side on to the throats. when running only on the primary throat things were fine but as soon as you opened the secondary it would flood as the secondaries were starving of fuel. air either needs to enter from all sides evenly or perferably from above. Thats why the ramflow foam aircleaners work so well on the webers. Now with the corolla carby im now using i was running out of power high up in the revs with the standard sierra hat. turning the hat to different directions helped a little but it still lacked top end. remove the hat completely and it would pull heaps better. so after alot of looking and playing about i have a curved rubber bend ontop of the carby that conects to the stock airbok. doesnt look very flash bt it works well.




All this was done on the old engine that was very worn and abit smokey but it loved to rev (8000+rpm)



B4T

this is what i did with the weber. the only way it would work properly with a snorkel and stock airbox.

the idea was simply to reduce all the surface heat that is radiated as the air travels along
though thatss a pretty good way to increase air flow and distribution, does it cclear the hood and what hose did you use

this is what i did to get my sierra carby working reliably. possibly
not that great for people that don't live in the tropics.

http://www.auszookers.com/index.php?nam ... pic&t=4574

i find cold starting on a frosty morning without a choke easy
pump the peddle 5 times or so then flick the ignition

(for those who dont understand the each pump squikrts some fuel from the accelerator pump, gives a rich mix.... like the choke)

what the thing you use to block the hole left from the choke shaft? i was going to us3 a nut and bot but that loooks neat

The weber is a tallish carby with that adaptor on it and it would not clear without a Body Lift. that hose was from an EA-EB-or ED falcon. (not sure what one). its too big to fit the corolla carby but ive done similar with some rubber bends i had lying about from previous cars ive had. When i get time ill scavange the wreckers again to find a better fitting and better looking one for the corolla carby.

im using a manual chokeas i got sick of shitty manual sucker

Santos wrote:
what the thing you use to block the hole left from the choke shaft? i was going to us3 a nut and bot but that loooks neat

i used a holley blank off kit, it has a few different sizes of fuel safe blank offs.
i now have that carby on a 1.6 and while it still works well, is a bit lean in low
rev full throttle situations. i think that i will get some jet drills and do some experimenting.

just pull the jets from 1.6l->1.8l carbs
i havent confirmed it yet but i think aisin, nikki & mikuni 2 barrell downdraft jets are interchangeble

Santos wrote:just an update still no jets but i been playing around with the airbox hat, a IR themometer showed that the black hat was 33-38 degrees after an hours drive. ambient temps 17-22

i painted a spare one i had bling aluminium silver, same drive and it measured 21-25 over the last two night, ambient temp 16-19

10 degrees have by just changing it to colour that reflects the radiant heat, so my plan is to bling up the intake to reduce heat temps on the intake side, i dont want to much cold air as i want 100 vaporisation but not so hot it causes detonation and loss in air density

air tempurature will be completly different to surface of metal tempurature

Imagine your engine at 3000rpm
that is 50 revs per second

engine capacity = 1300cc

So every second 1300cc x 50 = 65000cc (0.065 cubic metres) of air go throw the intake

so every minute 3.9 cubic metres of air go through the intake

Now not going into thermal dynamics of cooling air and heating of air due to friction as it passes through the air filter and all the other extremely complex varibles that people who studied at university for many years and then landed a top job designing engine components for a world leading car amnufacturing company but dont think they would have missed out on this extremely important revaltion that painting an air filter might decrease engine emmisions by lowering intake air tempurature

If you want to lower air tempurature going into the engine to create a denser air that has more oxygen so increase the burn and creates more power per stoke thus saving fuel then you need to take the heat from the itake air and move it elsewhere. this can be done with an intercooler. this can be researched more and discussing it here will take this topic right of the topic.

and remember drag cars get better times on cold nights. why cause the air is denser thus more oxygen thus more burn quicker.

its not rocket science but it is close so painting an intake like painting the space shuttle red so it goes faster.......

all true but to a point. if the air is denser on a carb from what i understand you are leaning the mixture and possible vaporising less fuel, which may increase emmisions

(its one of the reasons why canadians talk about better fuel economy summer, or a loss when removing the egr)

10 degrees surface temp may sound like nada but if its radiating 10 degrees less along the tract then it must be less in the total equation (even if at 3000rpm 10 only effects 1 degree in air temparature) its ugly and if the fuel economy stays constant i will be stripping it and sticking with bare metal and a clear coat. maybe suzuki felt a new engine bay has to be appealing to customers (marketing) or it was so simple an idea it never occured to them because they where thinking about making a engine that was adaptale to so many configurations (8v, 16v, efi, carb, fwd, rwd etc etc)

also drag engines are under a little more cylinder pressure then your average 1.3l, it may very well fill with more cold air and still sink all its heat into vaporising the fuel (which is mixed further in turbulance and pressure) and give good power

uni graduates are not infallable, neither are car companies, both GM usa and chrysler are excellent current examples

(if there uni bosses cant make right decisions what makes you think their uni engineers dont make the same mistakes, or have to meet uni bosses expectations)

you have a carby

don't forget the racing stripe down the inside of the airbox for extra turbulence.

And before you post results of 3.8 billions of fuel saved per tank make sure that you give accurate and I mean acurate comparasions

Like ambient tempurature recorede for the whole drive
You drove exactly the same way and in the same gear for the whole trip
you need a control comparision. so set everything out just like year 9 science, with a proposal, test subject devices used extrc etc etc.

Are you going to paint your radiator silver now too for better heat transfer????
will you paint you heater core black to get more heat in the car???
will you polish your car for less wind resistance?

i get the feeling your mocking me jock

but i intend to leave the radiator black so that it radiates more heat thereby cooling the fluid.

i drive from the north shore to inner west 3 times a week for the last 5 years, with a variance of 0.5L my figures tend to be fairly consistent, if i notice a drastic move in either direcion with 2 tankfuls i start trouble shooting

very close to actualy putting the carb & intake on the car, just dont want to rush it and fail.

one thing i thought of was putting a electronic vacuum switch t piece on the vaccum actuator to light a bulb when the second throttle is on. it would help with working out things like load and fuel economy.

so from what could i canabalise a switch from? i vaguely know carby autos have vacuum switches to activate the gears selection but i was hoping there was an easy source?

75 series cruisers have a vacuum switch on the airbox.

a mate used one to switch a supercharger on when it was at full throttle

Santos wrote:very close to actualy putting the carb & intake on the car, just dont want to rush it and fail.

one thing i thought of was putting a electronic vacuum switch t piece on the vaccum actuator to light a bulb when the second throttle is on. it would help with working out things like load and fuel economy.

so from what could i canabalise a switch from? i vaguely know carby autos have vacuum switches to activate the gears selection but i was hoping there was an easy source?

Some tech to help you
http://autospeed.com/cms/title_Using-a- ... ticle.html

also you can get vacuum gauges at most auto stores. the are also can "econometers"

thanks jock, already on to that

got to get one that is not made to fit in the car, the signal is dampened/filtered to stop it jumping around ... which is what i want it to do

got a g13ba swift carb, makes the sierra one look low-tech
it has
092/153 jets

the one design feature that i liked was the venturi only jut out and dont have a support arm, which gave me the courage to cut the arms off the sierra ones and putty up the crevices to streamline it a little, increase air flow

initially i was worried it might mess with my signal to much, but seing as i have filled in the little valleys on the wall which strengthened it i think its balance it out.

now that i got all the major stufff done i am going to go with the original 99 primary and the 1l daihatsu 141 as the secondary. soak it all with carby cleaner and put the gasket kit on

the two things i'd also like some ideas on are what can i coat the float with so the ethanol wont soak in it

and

where do i buy/find tappered head m2/m3 bolts so i dont have the bulging bits sticking out on the throttle butterfly (less restriction)

Santos wrote:thanks jock, already on to that

got to get one that is not made to fit in the car, the signal is dampened/filtered to stop it jumping around ... which is what i want it to do

abw do an automotive style vacuum gauge , that is probably your best bet , i can see why you dont want a dampened one, my vacuum gauge is one of my favourite tools , it can tell you a lot about an engine that you cant see. can tell you if a carb is incorectly tuned , or a leaky valve , a blocked exhaust and many other things.

another thing , your swift carb what year is that off , because it should be off an A engine , the ba carb is not a direct bolt on , the A engine carb is a direct bolt on and had a 104 or 105 primary and a 141 secondary jet

thanks suzimad,i was hoping to find the g13a swift jets
(any chance you know the g10a sizes?)

i got a hand held gauge in the post from the states.. no autoshops sell them and i figured a usa made is better than a china one ($28 new inc post damn lucky)

i got a spare g13ba carb witha parts engine i bought and i am guessing that your talking about fact thy are held down by nuts rather than bolts? (i guess if you where keen you could buy shorter bolts to fit on a sierra) it also has things like an underslung accelerator pump and electronic choke. (mine had a spiderweb of hoses and checkvalves) i dont think it is a 'sane' idea to try to use one to solve carby problems on a sierra

i also have a spare 'sierra' carb thats the one i am rebuilding
the jets are 099 and 105. thought it might be a mistake but a thread on auszookers.com had the same jets, i think 99/141 may be ok combo the first being not as lean as 92 or too rich as 105 and the 2nd jet may mean i dont run out of steam at higher revs, just speculation (might have to buy that wideband sooner )

been playing around mathematically trying to find a loose pattern but its hard,