Vacuum Line on TB, What for??

[AnthonyR23]

Hey so on my 347, with Trick Flow top end, with powermax 2030 cam, I am looking to replace my 65mm TB, Cold Air Intake kit and 70mm Mass Air Meter said to be cal. for 30lb injectors which I have for a 75mm Accufab TB, 4 inch anderson power pipe, and a velocity PMAS MAF cal. for 30lb injectors.

So first thing I am looking to get is the Throttle Body, It says the Race version of the throttle body has the 4 inch opening so I am thinking I want to go with that version, but still want to run the 75mm EGR Spacer, while keeping the EGR system functional rather than switching to a blank spacer. They offer the regular EGR spacers from accufab that are 75mm, just wondering if I will run into a problem using the 75mm race throttle body. Only difference is that it doesn't have that Vacuum Line on the TB.

Just wondering if this will cause me any headaches. Any opinions about this? Thanks!

 

[ID89GT]

That is for the pcv system, recirculates blow by gases back into the intake to be reused.

 

[AnthonyR23]

Well if I want to retain the PCV system, couldn't I just have the PCV system connected to one of the other manifold vacuum sources? With a vacuum T connector for example??

 

[liljoe07]

Posted via Mobile Device

The throttle body hose is the fresh Air intake tract of the PCV system. If you don't run it, you apply vacuum to the crankcase, and wind up with oil in the intake manifold. The Throttle line is to make sure the crankcase gases have a way to circulate.

You can mount a fitting on the Air duct tubing, and connect it to the filler neck tube. Just can't vent the crankcase by pulling air from in front of the MAF sensor.

 

[AnthonyR23]

So I just had the tb vacuum line hooked up to the oil filler neck tube, so like your saying, then I could just hook up a tube on the power pipe that would do the same thing, right before the tb, but after the mass air meter.

So for the PCV system itself, and the PCV valve, it is just hooked up to manifold vacuum, which is correct right?? Assuming the Valve keeps only the vapours from escaping to the manifold.

So if I do that then do you think I should be okay with the 75mm race version of accufab's throttle body's with the 75mm egr spacer.

 

[liljoe07]

1So I just had the tb vacuum line hooked up to the oil filler neck tube, so like your saying, then I could just hook up a tube on the power pipe that would do the same thing, right before the tb, but after the mass air meter.

2So for the PCV system itself, and the PCV valve, it is just hooked up to manifold vacuum, which is correct right?? Assuming the Valve keeps only the vapours from escaping to the manifold.

3So if I do that then do you think I should be okay with the 75mm race version of accufab's throttle body's with the 75mm egr spacer.

1- Yep sure would.

2- Manifold Vacuum is what pulls the Crankcase pressure out. The PCV valve lets air only flow one way.

3- Yes.