albertz
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| posted on 17/5/05 at 09:01 AM |
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Weber carbs on Toyota 4AGE - advice required!
I am considering modifying my 4AGE engine to run on Weber twin 40 carbs. I have identified a set that I think are not be too far away from the spec I
need, but would be grateful if anyone can check that these are OK. My knowledge on this type of thing is very limited...
Choke: 29
Main Jet: 120
Emulsion Tube: F9
Pump Jet: 40
Idler Jet: 45F9
Does that sound anywhere near right? If not, what are the likely costs of getting them correct?
Other than the manifold what other expenses am I likely to incur changing from the standard fuel injection to carbs? How difficult a job is it to do
and what happens to the standard ECU and wiring/electronics?
The main reason for doing this mod, is that I have removed the TVIS system, to enable the newer inlet manifold to fit, this has resulted in
disappointing performance at low revs. Would this modification overcome the problem? Could the TVIS be used in conjunction with the carbs?
As I say, this is not my strong point and I would appreciate any guidance. Don't worry about spelling out the basic as thats exactly what I need
to know.
Sorry for the multiple questions.
Cheers.
[Edited on 17/5/05 by albertz]
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mookaloid
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| posted on 17/5/05 at 09:23 AM |
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I have realised after messing about for ages that the only real way to get webers to run correctly is on a rolling road. With someone who knows what
they are doing....
I have a pinto which is well documented and mine still needed some changes to the carbs.
Cost will depend on how many jets emulsion tubes etc need replacing.
Sorry couldn't be more help
Cheers
Mark
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awinter
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| posted on 17/5/05 at 11:33 AM |
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Chokes
Hi, don't know much about the 4age. I assume this is a 1600 130bhp unit?
If it is I think you choke sizes are too small. You should be looking at 34mm choke really. As for the jets etc, as already said get it to a rolling
road and get it setup properly.
If the engine has been modified to increase BHP it may be worth considering running 45's with a 34mm choke as this will then allow you to
increase the choke size. A 36mm choke in a 40 carb does not give any increase in flow, sounds crazy but thats how it is.
Also how are you going to get a spark, the the 4 age engine ignition controlled by the ECU?
For comparison, Peugeot engines, 1.6 8v 115bhp 32-34mm choke 1.9 8v 130bhp 34-36mm 1.9 16v 160php 36-38mm chokes.
A smaller choke will give you better bottom end but limit top end power.
You do need to consider ignition, if the timeing is way out you will get poor throttle response and lack of low end grunt.
I have a set of twin 45's in a Pug MI16 engine in a 309. about 160 bhp at the wheels. The ignition timing is ajustable via the dizzy. I had it
setup on a rolling road and it makes such a difference to fuel consuption and performance. Once the carbs are setup its a DIY job to balance them
twice a year as they need doing with the change of air temp.
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garage19
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| posted on 17/5/05 at 11:35 AM |
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It says advice needed so here goes.....
Stop struggling with the carbs and get yourself injected!
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albertz
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| posted on 17/5/05 at 12:06 PM |
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At this stage i am just trying to get a feel for the amount of work/complications involved.
As i mentioned in the original post i am having a low rpm problem at the moment, due to the TVIS being removed. It may prove simpler to try and
re-install the TVIS somehow, hopefully by doing that the problem will be gone.
I dont really understand the system yet, but i have seen or heard of people using carbs on these engines, so it must be possible. What i need to know
is:
1) What carbs setup is best
2) How i get the engine running with carbs i.e. ignition
3) Cost and hassle factor
This is a fairly long term idea, as having just built and tested the car i want to use it for a bit, also i am skint!
Thanks for the pointers so far, keep the comments coming please.
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awinter
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| posted on 17/5/05 at 12:21 PM |
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Found out what the TVIS is. You could not use it with carbs..
can you not refit it and junk the new manifold. That would seem the least cost option.
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chick
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| posted on 17/5/05 at 01:18 PM |
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I'm no expert on this, but here are my ramblings:
The newer 4-AGE works without TVIS - I thought this was because the inlet ports were smaller than the TVIS version.
With smaller ports you get faster air flow at low rpm, and so better combustion mixture I think?
The TVIS blocks off one input port at low rpm - effectively giving smaller input ports
Could you reduce the size of the input ports by putting some of that "metal putty" stuff which is used for reshaping ports? This might
give a faster
air flow and better low end power - it also will
hurt top end power though. Maybe the ports can
have their shape changed to improve air velocity at low RPM?
I guess someone who knows a lot about this
would have to do the work, as they would need
an airflow bench and air velocity meter?
Tim
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bigandy
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| posted on 17/5/05 at 03:51 PM |
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I'm hoping to go with either an Emerald or megasquirt Engine management on my Mojo, and that is using a 4a-ge engine. my plan was to junk the
TVIS system, as it seems awfully complicated for a bit of low end power.
Why not just use both ports (as if the TVIS was in high rpm mode) and accept slightly less grunt lower down the rev range. Bearing in mind the 4a-ge
was put in heavy cars like the MR2, when it is installed in a lightweight locost type car, it shouldn't make much difference at all.
At least, that's what I think!
Andy
Dammit! Too many decisions....
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nicksertis
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| posted on 17/5/05 at 04:10 PM |
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TVIS Info
Incase anyone was wondering why the TVIS system was inplace, this helps to explain:
http://www.toyotacelicaonline.com/celica1/TVIS.htm
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britishtrident
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| posted on 17/5/05 at 04:28 PM |
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quote:
Originally posted by albertz
I am considering modifying my 4AGE engine to run on Weber twin 40 carbs. I have identified a set that I think are not be too far away from the spec I
need, but would be grateful if anyone can check that these are OK. My knowledge on this type of thing is very limited...
Choke: 29
Main Jet: 120
Emulsion Tube: F9
Pump Jet: 40
Idler Jet: 45F9
Does that sound anywhere near right? If not, what are the likely costs of getting them correct?
Other than the manifold what other expenses am I likely to incur changing from the standard fuel injection to carbs? How difficult a job is it to do
and what happens to the standard ECU and wiring/electronics?
The main reason for doing this mod, is that I have removed the TVIS system, to enable the newer inlet manifold to fit, this has resulted in
disappointing performance at low revs. Would this modification overcome the problem? Could the TVIS be used in conjunction with the carbs?
As I say, this is not my strong point and I would appreciate any guidance. Don't worry about spelling out the basic as thats exactly what I need
to know.
Sorry for the multiple questions.
Cheers.
[Edited on 17/5/05 by albertz]
#
The existing jetting would be about right for a Hillman Imp engine !!!!
If they have came from a small capcity engine cjeck the accelerator pump stroke hasn't been shortened.
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albertz
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| posted on 17/5/05 at 05:27 PM |
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I am planning to look at my car to see what will be involved in putting the TVIS back in. I am not 100% sure that is what my problem is, because i
have spoken to several other people who have ditched the system with no noticeable affects on their cars.
The reason i took it out in the first place was because i needed to modify the inlet plenum to clear the bonnet line. The plenum which uses the TVIS
is much more complicated to mod, therefore i chopped a non TVIS one and discarded the TVIS.
There may be other factors involved and as i have just got my car on the road i havent fully investigated the potential problems. Basically what i am
saying is 'dont take my word for it, but the removal of the TVIS has had an affect on my engines performance'.
I am swaying between keeping the FI or abandoning it altogether in favour of carbs.
Having done a bit of light research on the Toyota websites and forums it seems that the general consensus is to stay with the fuel injection.
I dont know..........
I would still like to know what exactly is involved in making the carbs run, specifically with the ignition system. Any information appreciated.
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bigandy
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| posted on 17/5/05 at 06:12 PM |
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Personally, I'm still convinced an aftermarket injection setup is the best way forward. Like that link posted above said "T-VIS does
offer a small mid-range torque advantage over the non-T-VIS equiped Toyota engines of the day"
I think the emphasis is definately on small, and for what its worth, I couldn't tell the difference when I disabled it on the MR2 that I was
driving around before I took the engine out.
In order of bestness (bestest first), I would go with:
Aftermarket FI (Megasquirt/Emerald etc)
Toyota stock TVIS
Carbs...
Afterall, you don't see modern cars/race cars running carbs do you? (or do you?! go on, someone prove me wrong!) 
Cheers
Andy
Dammit! Too many decisions....
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DEAN C.
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| posted on 18/5/05 at 12:49 AM |
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Hi,I'm sure that you could use the standard ecu without connecting your injectors if you went the carb route , to save money on an aftermarket
ecu.
I have managed (just) to squeeze my TVIS manifold(RWD) under my Indy bonnet without mods or chopping.
Failing that I would make my own manifold from steel tube as I mentioned before,see Eddy McClements site.
This would cost very little and you could replace the TVIS butterfly chokes.
Once I've finished a project why do I start another?
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DEAN C.
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| posted on 18/5/05 at 12:53 AM |
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Hi again,just thought of another option for you.You could fit a later small port head and your chopped later non TVIS manifold,this would basically
give you the the late non-Tvis set up.
Once I've finished a project why do I start another?
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rick q
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| posted on 18/5/05 at 03:22 AM |
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Stick with EFI - only way to go IMHO
Have a look at www.geocities.com/MotorCity/Garage/8422/4age.htm
and
www.billzilla.org/carindex.htm (down the bottom of the page).
All manner of useful stuff in there
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albertz
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| posted on 18/5/05 at 06:40 AM |
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Just an update on last nights developments.....
I came up with the 'brain wave' of cutting the flange of the TVIS manifold and using it as a spacer between the TVIS plate and the non
TVIS manifold. That way, i should very nearly replicate the standard setup, airflow wont be quite as good as original and the runners will be
approximately 12mm longer but it is free and worth a try, with nothing to lose.
I am machining the flange flat tonight and will hopefully have it fitted soon. Will let you know the outcome.
I considered replacing the cylinder head, but am concerned because the wiring looms are not identical and i might find that electrical
plugs/connections wont fit etc. I have not really investigated this yet though and could well be wrong.
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albertz
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| posted on 18/5/05 at 08:25 PM |
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Vacuum hoses
Does anyone happen to have a layout diagram of the vacuum hoses for this engine?
If so i would be very grateful.
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ginns72
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| posted on 21/8/11 at 08:52 PM |
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hi dose enyone no where i can get a 4age inlet manifold from for the carb converion eny help would be great cheers
[Edited on 21/8/11 by ginns72]
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tul214
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| posted on 22/8/11 at 04:26 AM |
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Fensport
1.6 Raw Super6 sold
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