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1971 240z ITB install


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Drill and tap the intake runners!!! I'm assuming the intakes you are all using don't have bosses already, but that's where you should be drawing vac from if you don't have dedicated ports. The kit for the Jenvey ITB's from Datsun Spirit have these ports built into the manifold. 


Boogering up the ITB bodies are not the way to do this, the OER piece tioga mentioned is a nice way to add the port as well if you don't want to mess with drilling and tapping the intake. 

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On 9/7/2019 at 12:11 AM, DuffyMahoney said:

I asked some more questions. 


Here is the original email. Maybe IAC can handle the idle and allow me vacuum? 



This looks like a copy of the original SK "Air Governor" setup I installed back in 1983 with the SK Analog Fuel Computer! Good to see nothing changes!
The SK's wouldn't idle at all when you closed the throttle plates and it was a very fine method indeed to get the plates open to allow 950 rpm idle... Ended up closing them altogether anyway and used the ports in the Mikuni Manifold as the idle air bypass port at idle through an 82/83 Idle Speed Control Screw refit for 1/4" tubing that went from the Surge Tank to the Manifold. One screw to set on the idle speed, and a simple solenoid bypass line from a Suzuki or Toyota EGR valve that allowed it to idle up when cold (like 1700)... That was on some thermal switch we found that closed electrically and opened the bypass below 160F...

All the talk here about high idle on Jenvys corresponde to what I've seen on them as well--the bypass screws leak. You almost have to gob RTV over the jam nut and adjustment screw to make them hold the speed, and not introduce tramp air! Somewhat disappointing.

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Hi Tony,


I don’t think that is what is happening. The original air bleed screw is longer with a taper that seats in the bottom if the bore to block the correction air port in the throat of the body. That is how the bleed screw works to balance flow. The opening to the front side of the butterfly is unrestricted and the taper at the bottom regulates the flow. Just like a mixture screw. The problem is the air ports jenvey sells just have a short threaded section that threads into the top of the body and does nothing to block the passages in the body that allow adjustments of air flow thus you have full air flow. That is why I suggested you would need to block the port in the throat of the body on the air filter side. 

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