how do i adjust side draft carbs? i have a set of webers that i am putting on a 3TC and i am putting dual webers on it. any help would greatly be appreciated. thanks
your engine is a bit larger so I would change the chokes to 32mm or maybe even a bit larger depending on what was done to the head, increasing the main jets .05 per mm of choke increase, and maybe the idle jets if needed.
As far as tuning goes, it's pretty much like voodoo; each adjustment effects the others in differing proportions so as to create a balance.
Hope that this helps.
automatic> thanks for the info and specs, that'll help alot!
Darkprince114> OH HELL YEAH IT WILL!!!!
also got a full length header, cam, ported and polished head with 7 angle valve job too. car is going to fly after this. i just saw on the Moroso catalog that they now make oil pans for the 3TC and 2TC. right now i'm trying to see if i can put together an ignition system. i am hoping to go crank-trigger, but who know what i come up with. thanks for all the help guys
Nothing beats the sound of a bank of weber sidedrafts. Damn, I had a pair on my old Mitsubishi and I still remember that throat action. Even that hissing at idle.
And those years of constant swapping of throats, tubes and jets.
I have seen huge, thick, books written about tuning them.
You got 40 or 45mm ?
Single or twins?
2/3TC is a 1.8 litre engine right?
2 x 40mm or a single 45mm would be about the right size.
Do you know what the peak hp rpm is going to be according to the camshaft?
Another thing to do is to use the velocity stacks if at all possible, and use some motorcycle foam sock-type airfilters; it'll help with tuning as well as performance. Without a smooth airflow going over the auxilary venturis, you'll get turbulent airflow that'll be difficult to tune around, along with the fact that they'll add some hp all around. If you haven't purchased any yet, try and get some that flare out 10mm or so over the 2" length.
For the brake booster, it's ok to just pull vacum from one cylinder, better than linking the cylinders together.
You may need a low pressure fuel pressure regulator, Webers run at only 2.5 psi I believe.
running 2 x 40, but jetting it on the rich side to compisate for direct port nitrous
and yes, i love the hissing and the "deep throat" action sounds.....hehehehehe
for the vacum, i'm running going to reuse the old air pump and turn it into a vacum pump for the accessories and yup, got some of my parts from BRDracing.com.
thanks for all the help guys and i will post pics soon and when all is finished, i will post dyno numbers too
It takes a lot of gas to keep your mixture correct when running nitrous, WAY more than just running a bit rich anyways. Might want to re-think that one, or better yet, just add a some more holes into the manifold for fuel injectors and do yourself a big favor, go fuel injected, use an S-afc, and forget all the little jets, stinky, gas dripping carbs.
Anyways, do you have a linkeage setup?
You'll have to spend some time synchronising the carbs in order to get them to idle.
Your linkeage should be setup to have one screw to adjust all of the throttles so you can change the idle speed.
The air screws should start out at a couple full turns out, keep turning one screw, no more than a half turn at a time, waiting for a few seconds to let it even out. Do this adjustment until you get a higher idle from the turning of the screws, use the linkeage/throttle plate adjustment to bring it back down again when the idle gets too high.
Keep doing this until you get down to tiny adjustments to the screws and the idle is smooth.
It's important to get the throttle plates synchronized first or else all the fussing with the air screws will be off as soon as you move the throttles, accelerate.
automatic> i would love to go fuel injected with individual throttle bodies, but i don't know how to go about it. any suggestions? or were you just refering to the nitrous setup as far as fuel injected? i have the linkage and it only has one screw for adjusting. i would love to go MoTeC fuel injected, that would be the shit! who makes the S-afc, is it Apex'i?
The carbs would work great as throttle bodies, injectors could be added into your manifold.
Your car never came with fuel injection, so the s-afc would only help after you actually had a base system installed, and running.
You need to do some research and try to find an ignition distributor that'd support a fuel injection system from another vehicle to use,putting in a high pressure fuel pump, line/return fuel line, would also have to happen.
It sounds like a lot of work, and it is, but so is trying to setup and tune a set of carbs.
With my webers, i disconnected everything, just bare carbs on manifold to make sure i had no linkage issues. The linkage had quick release caps so it was easy to do. I had twin 40s and i matched them first using vacuum meter on each throat. Then I used ear and vibration of the engine to clue me in. I use the meter again when I was done. Even if I know jets/tubes/throats are not spot on, at least the 4 barrels are balanced. Good baseline.
I would not compensate for nitrous yet, you have to get it as good as you can go before you introduce something like that. Nitrous is when you need more. If you don't know what you got - how is it more? Jetting rich is safer, but remember that most of cars life is spent on idle circuit. So a rich read at higher RPMs may not be correct indication.
All carb tuning starts at float level, then primary / secondary circuits. I know there are a lot of knowledgeable people here but that is the magic of it. One step at a time and forget the haha gas for now.
??? Is your car f/i? not so easy to add unless you do a full transplant.
^^-- thats what i'm going with instead of motec. i found a very nice custom intake for sale pretty cheap with the bosses for the injectors and the rails already on it. intake has blacktop 20V throttle bodies and runners to match 3TC head. gonna be fk'n sweet when i'm done! but thanks for all your help guys, i really do appreciate it!
Oh my, that's a pretty sweet ecu, should make things alot easier in the long run, and your fingers won't be smelling like gas, cracking at the fingertips for weeks on end while you mess with those old carbs.
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