2T Single Cam upgrade help

[king-szeitszam]

I would get a weber 32/36 its the most common and the easiest to work with, theres a dual throat weber on ebay at the moment, that would go great with a 2t, theres no point running twin carbs on a 2t, i really wanted twin carbs, but trying to do all 3 upgrades (twin carbs,cam and extractors) is too much of a hassle and you'll probably regret it. a 32/36 weber would be my choice or a holley 350.

Thanks for your reply! I think I've seen that weber online, $850 is expensive! If that's the same one. Besides, couldn't justify buying that one when I have the original carby sitting here...although would love to.
Im inclined to agree with everything you've just said- however why would I regret the twin carb+cam+extractors setup? Keeping in mind I already have the extractors and carbs on there.

[ctrain]

this is the carby mate

toyota celica ta22 ta23 dual throat weber + wrecking | eBay

Why i say you might regret it is because in the long run the carbs will need servicing and maybe a re-tune which will cost twice as much, but that depends on how you drive. If you do get this all sorted out and get the 2t running great. It will probably make me go back to getting twin carbs as your the only person on toymods to my knowledge that has the twin carbs-cam-extractors upgrade on the 2t, and there hasnt been anyone to confirm that this setup runs great and puts out good power figures so im hoping it all works out for you.

Peace Out

[king-szeitszam]

Why i say you might regret it is because in the long run the carbs will need servicing and maybe a re-tune which will cost twice as much, but that depends on how you drive. If you do get this all sorted out and get the 2t running great. It will probably make me go back to getting twin carbs as your the only person on toymods to my knowledge that has the twin carbs-cam-extractors upgrade on the 2t, and there hasnt been anyone to confirm that this setup runs great and puts out good power figures so im hoping it all works out for you.

Damn, that makes me want to keep going ahead with it.
I CAN say that it's currently running fantastically.. absolutely no complaints there and easily gives Commonwhores a run for their money at the lights. My problem being that it achieves this at a massive fuel cost..one I probably can't sustain for too long.
30 litres gets me about 200km, 150km on a bad day. That's $40 bucks gone already, gets me to town twice, if I'm lucky.
Full tank, looking at maybe 300km range on top of that, maybe 350km.

Not really sure what I'm doing wrong here.. thus the cam dilemma. Tighe describes it as an economy profile with power benefits.
See this page, specifically the first two profiles on that list;
Some Helpful Hints

Still unsure of what to do. Been quoted $260 for the new cam, another $150 on top of that will get me new valve springs which is probably a smart thing to do also. Then fingers crossed it actually makes a difference.
The theory being that if I can get a profile that brings it close to dealing with the fuel flow of a 2TG, but with a single cam, then it can be tuned accordingly.

However. I will sacrifice power in the interests of efficiency and reliability (To quote River).
This is a daily drive, not a track car or a weekender- as much as I'd love for it to be race-spec, it'd just be wasted money for me. The twin-carbs is already overkill.
It's an experiment I guess- can I make the twin carbs acceptable on the 2T as a daily drive.

I'd love to say the cam will do this for me, and a proper tune following that.
My question is- will it really?
So, keeping in mind its purpose, input?

Abuse/advice/thoughts/help- ok go.

[king-szeitszam]

Sorry, double post.

[NME308]

Hmmm... In no way am I attempting to say your twin carbs are not suitable for the 2T... In fact they are a much more refined and efficient product than my single carb!

A carburettor is a rather efficient fuel/air metering device which can cope with a wide range of operating conditions. Your twin carbs are not genetically coded to put out more fuel than a 2T can cope with. Someone has given them that instruction. Chances are they would run pig rich on a twin cam 2TG right now after the guys you mentioned have 'tuned' them. The carburettor will react to airflow past the venturi's and meters a given percentage of fuel into that airflow. A smaller flow from lets say a smaller or less highly tuned engine will get the same 'ratio' of fuel to the volume of air as say a fairly radical street terror pulling in ma's washing with it! Unless there are other factors coming into play such as poor ignition timing curve etc then a carburettor(s) from a tough 2TG should require only fairly minor tweaks to happily feed your 2T with or without cam upgrade!

River has once upon a time posted a thread with solex tuning information here:
http://www.toymods.org.au/forums/tec...rocedures.html Make sure you leave Uncle Rivs some rep on the way out!

Some interesting information here:
Carburators

And some more technical tuning info here:
Weber Carburetors Carbs 40 DCOE 45 DCOE 32/36 32/34 Jeep. Top-End Performance 818 764-1901

Now of course my definition of minor tuning tweaks may of course not be your cup of tea - I spent the weekend with my holley in bits with jet drill and lead sinker fine tuning some of the circuits... Your twin carbs will have much better adjustability than my holley if finessed by a patient man.

A single weber of more modern origin or at least more readily available components may in the end be more suitable based on how much time and or patience you care to spend on this little baby! I sure wouldn't suggest throwing the twins out just yet but it would be a better option than throwing a match into a classic celica!

Cheers,
Jason

[king-szeitszam]

Thanks for your very informative reply yet again Jason! Giving those pages a look now.

I've got to say though, this is becoming a bit of a headache
Tune or don't tune, cam or no cam, twin carb or single. I have no idea.

I've been in contact with the tuner now, he says that he actually de-tuned those twin carbs to suit the 2T single cam better. If that's true then I don't know what the problem is.

I'm kind of wishing there was just a shop I could drive the car into, leave it for a week, then have it come out tuned perfectly and running great.
Beginning to think it may just be easier to put the single downdraft back on and forget about it, because I can't afford the fuel how it is.
A camshaft mod requires more time than I have when it comes down to taking it out, putting it back in and re-gapping, re-tuning everything. Either more time, or more money.

Fuel efficiency is my priority, I guess I just don't have the time or money on my hands to get fancy with this stuff so I'll probably need to start looking at other options.

[boxh34d]

First up: I have no practical experience in tuning a multiple carb'd car or a 2T for that matter.
I have however been hanging around my mechanic / tuner enough when he's been tuning carb'd cars (including a couple of 2T, 3T/2T hybrid race cars, amongst others) to notice that pretty much ANY carb combo on ANY engine (within reason) can be tuned to achieve good performance and acceptable fuel economy.
As Jason has previously stated, there is no reason that the carbs should be dumping fuel in at such a rate that its pouring out the ass end of the car under cruise and acceleration. It is the jet sizes and pump circuit settings that dictate how much fuel goes in under what kind of circumstances. If the tuner can't get the carbs to stop dumping fuel in he either doesn't have the correct parts, the know how or won't spend the time to get it right.
Your last comment of:

I've been in contact with the tuner now, he says that he actually de-tuned those twin carbs to suit the 2T single cam better. If that's true then I don't know what the problem is.

sounds a lot from here like he has just nominated jet sizes to suit a warm 1.6L, without actually looking at YOUR engine properly, and the recommendation of changing the cam is to try and bring it closer to the airflow he thought it would have.
Take it to another tuner to fix it. Whilst it is likely very much worth while in changing the cam and looking at regraphing the dizzy, these don't sound like your current problem. If you were planning on doing the cam anyway do it first, but the long story short is:
Take it to a good tuner with the right knowledge and equipment to tune the thing properly.

[king-szeitszam]

G'day, thanks for your reply.
I was under the same impression as you, like Jason said before- the carby needs to be tuned to put too much fuel in, it doesn't do that automatically.
However I have called him again tonight, and he has assured me that the car is tuned as well as possible for a 2T setup- he says it simply cannot handle the same amount of fuel coming through as a 2TG can. According to him, this is why the cam is needed, then the carbies can be retuned to suit what 'should' be an intake comparable to that of a 2TG.

However a cam upgrade is a big job for someone like me... getting it ground is one thing, then there's all the rest of it. Timing, gapping, new valves, cam followers...money money money
All this for a marginal increase in performance and a POSSIBLE increase in economy...
On this tangent- could anyone tell me how much of an efficiency boost I could expect from a 2T TRD profile... 272 duration grind? In terms of litres per 100?

sounds a lot from here like he has just nominated jet sizes to suit a warm 1.6L, without actually looking at YOUR engine properly, and the recommendation of changing the cam is to try and bring it closer to the airflow he thought it would have.

Don't think jets have been changed at all.
On this note- do you think it would be a viable option to simply re-jet each of the carbs to a smaller width jet- therefore restricting the fuel flow and reducing usage?
Keeping in mind this is a 2T- designed to run on a single carb and thus less fuel.

[river]

Hi,

The stock 2T (in pristine condition) can put out 102bhp. A similar stock 2T-B, which has slightly higher compression and twin down-draft carbs, puts out 110bhp. So, the extra carbs you have isn't going to get you a great deal extra power unless you do some head and piston work. Also the 2T-G, in pristine condition, puts out around 120bhp. You're not going to magically turn your 2T into a 2T-G with the carbs (and exhaust) alone.

You can get a manifold to run a single webber for the 2T, or even a manifold to take twin down-draughts (aka like the 2T-B) and thye come up on eBay from time to time. And again, it won't transform your engine into a 2T-G. So the power gains are modest, but noticeable - especially if coupled with a nice set of extractors.

You will find the cheapest and most effective upgrade for a 2T is to put in a 2T-G... same as an upgrade for an 18-R is to put in an 18R-G. The 2T can make some amazing power, but it's a lot of work and it hurts the wallet.

Finally, if the carbs are dumping fuel so much then surely you'd smell unburnt petrol from the rear exhaust and I'd expect it would backfire like a bitch with all this pterol in the hot exhaust. Also... your plugs must get horribly fouled with all this unburnt fuel? There's no petrol smell around the carbs as they may be leaking? Or, the floats are jammed and over filling the bowls with petrol?

Why don't you send a PM to Rodger, who is on these forums and has a healthy knowledge on these carbs. He may advise a suitable jet size for your engine. Poorly jetteed carbs, as well as badly tuned ones, can chew up petrol and make the engine perform less than its optimum.

seeyuzz
river

[Silly Rabbit]

Put the single downdraught back on and be done with it. That is until you can either have it off the road to put the new cam in, or have saved enough dough to take the car to a proper mechanic / tuner who can balance and rejet the carbs if needs be.

All this talk of different grinds is pointless.

See the below picture. This is what I currently have sitting in my garage waiting to go in my club club. Do you know why I have it sitting there and not in the car? It's there because the 32/36 downdraught Weber on the current engine runs like a charm, is easy on the juice and is perfectly fine for 90% of the driving I do.

Only when I have the funds to tune and set up the twins properly, as well a change cam will I do it. Until then i'm sticking with the Weber.

[king-szeitszam]

Hi,

The stock 2T (in pristine condition) can put out 102bhp. A similar stock 2T-B, which has slightly higher compression and twin down-draft carbs, puts out 110bhp. So, the extra carbs you have isn't going to get you a great deal extra power unless you do some head and piston work. Also the 2T-G, in pristine condition, puts out around 120bhp. You're not going to magically turn your 2T into a 2T-G with the carbs (and exhaust) alone.

You can get a manifold to run a single webber for the 2T, or even a manifold to take twin down-draughts (aka like the 2T-B) and thye come up on eBay from time to time. And again, it won't transform your engine into a 2T-G. So the power gains are modest, but noticeable - especially if coupled with a nice set of extractors.

You will find the cheapest and most effective upgrade for a 2T is to put in a 2T-G... same as an upgrade for an 18-R is to put in an 18R-G. The 2T can make some amazing power, but it's a lot of work and it hurts the wallet.

Finally, if the carbs are dumping fuel so much then surely you'd smell unburnt petrol from the rear exhaust and I'd expect it would backfire like a bitch with all this pterol in the hot exhaust. Also... your plugs must get horribly fouled with all this unburnt fuel? There's no petrol smell around the carbs as they may be leaking? Or, the floats are jammed and over filling the bowls with petrol?

Why don't you send a PM to Rodger, who is on these forums and has a healthy knowledge on these carbs. He may advise a suitable jet size for your engine. Poorly jetteed carbs, as well as badly tuned ones, can chew up petrol and make the engine perform less than its optimum.

seeyuzz
river

Evening River,
Thanks yet again for a well informed reply- every time I read something on here that you've written I realise what a noob I am still!

To be completely honest, the twin carb option was only chosen because it was the cheapest at the time- picked up my set for $250.
I've read your threads on the specs of each of the motors and know that there is no way my 2T will match a 2TG by any stretch of the imagination...not without a lot of money behind it at least- even then.
My intention was never to build a powerhouse or a race-spec car. Honestly, if I could get the twin's running solid, but very lean at the same time, at the sacrifice of power, I'd do it instantly.

I'll get in contact with Rodger for some more info.
Re-jetting seems like a good option for reducing fuel usage. Confident there are no leaks as i checked today- however will check floats/bowels to make sure of those.

Edit: Silly Rabbit

An impressive set up you have there, and wise words of advice.
Will any Weber do? Or would you recommend anything in particular.
I assume this means a new manifold would be required also.

If I can get the current twins re-jetted and tuned- would you suggest keeping them on?
Also, from what you have said you imply that a good cam is absolutely necessary for a twin carb set up.. did I interpret that correctly?

[river]

Hi,

If I can get the current twins re-jetted and tuned- would you suggest keeping them on?

Absolutely!!!! Throw on a nice set of extractors and you'll have a sweet little engine.

A "good" cam is not necessary. It's nice to have something a little more aggresive to get more performance, as the stock cams are designed for easy driving and economy with good power through the rev range. Everything is a trade off, so a more lumpy cam will get you some more power, but the power will be higher in the rev range and therefore you lose the low down performance, and you'll probably consume a little more petrol as you'll need to get higher revs to get power.

First thing is PM Rodger and tell him all you know about the set up, what was done etc, and point him to this thread. See what he says. If you need new jets then get them. Then find a good tuner where you live. I wouldn't go back to that guy you've been going to. Then, when the engine is running nice and the economy is better I'd look at extractors.

We were all noobs once and the best thing us more experineced people can do is to assist and help those that are keen to learn. In years to come you'll be the old wise hand and noobs will be asking you questions. Remember this time and help them as much as you can.

seeyuzz
river

[boxh34d]

I was under the same impression as you, like Jason said before- the carby needs to be tuned to put too much fuel in, it doesn't do that automatically.
However I have called him again tonight, and he has assured me that the car is tuned as well as possible for a 2T setup- he says it simply cannot handle the same amount of fuel coming through as a 2TG can. According to him, this is why the cam is needed, then the carbies can be retuned to suit what 'should' be an intake comparable to that of a 2TG.

Don't think jets have been changed at all.

These statements contradict each other perfectly.

Fuel metering is like food for people. If your an average person with average dietry needs, and someone decides to feed you the same amount of food as a body builder, or someone who swims 20km per day, of course, you won't be able to use all the food being fed to you. Which is the most reasonable solution? A Altering your diet to suit your activity level and requirements, or B change everything about your life and physical abilities to be able to swim 20km a day to use the food being put in front of you. I know which sounds easiest and most reasonable to me. . . .
The amount of fuel required by an engine is directly proportional to airflow which equals power. A petrol engine by its nature has it's power controlled by limiting airflow, and then metering fuel according to that airflow. To tune the engine you jet the carbs to suit the airflow of the engine, not the other way around.

There can be problems tuning due to carbs being WAY too large and not getting enough air velocity (and pressure differential) resulting in poor fuel mixing and atomisation. I would hazard a guess however that a pair of 40's would be nowhere near that far too large on a mild to warm 2T. The one time I've seen this happen, it had nothing to do with the engine running rich and using fuel, it just runs like shit and is uncontrollable at anything other than high revs and full throttle.
Once again, I would strongly suggest TAKE IT TO ANOTHER TUNER AND AT THE VERY LEAST GET A SECOND OPINION!

Edit
Stupid slow net taking an hour to post.
I think River and Silly Rabbit have made the point better than I can.

[lt1972]

River. Im far from the perfect mech but I did manage to acheive compression of 175psi per cylinder when I rebuilt the engine so we should have a very good base to work with. The single that was originally on was an unknown hand me down causing too many problems. Twins got adapted to suit. Been too long since I tuned twins so I advised ks to have them professionally done. Unfortunately I did not know anyone up here in briz to recommend. I do however feel that if the jets haven't been replaced then this would be the place to start.
Car has 4 2 1 extractors to 2.5 with high flow resi and muffler. No cannon bs
P s k s phone went dead sorry haven't had a chance to reply.

[lt1972]

One other thing I pointed out to ks and was not sure of myself. The twins fuel rail does not have a return line. Could this also be causing the problem? The floats seat well and there is no fuel bypassing when the elec fuel pump is on and car not running though