I am in the middle of removing my Smog pump and it's equipment. More to free up space under hood than for HP gain.

I have a vacumm valve inline with the passenger side exhuast. Between manafold and Y- pipe. Should I pull this off? is the valve obstructing flow? would I need to put in a shim?

also, Is anyone using the smog pump to pull a vacuum on the crankcase. Pictures of this mod would be nice.

 

That valve isn't hurting anything if you still have the stock manifolds, y-pipe, & cat. However, Chevy High Performance magazine, in their "My Generation Camaro" series, thought it was causing restriction with their TES system, after the engine dyno'd at 380HP with similar shorties but no EFE valve (that's what it's called).

Personally, I left it out since the Hooker 2055 headers don't make provision for it. It hasn't been missed.

 

I am having trouble picturing the valve you are talking about. Any pics or further details?

 

looks like this. on the pass side between y-pipe and manifold.

 

If there is no vacuum on that valve, then it will remain open....Under normal vacuum routing once a cold engine is started the valve closes (has vacuum). The valve opens(no vacuum) after the sensor on thermo housing heats up to operating temp......thats it!

 

holy crap tell me i dont have that thing on my exhaust!! I belive it was only carbed cars because i have never seen that huge mass anywhere.

 

Only used on carb'd cars.

It can cause a restriction even if no vacuum is applied and it stays open. But, as I said, with a stock y-pipe, it isn't going to be any more restrictive than the pipe.

I should have said CHP's 355 for their "My Generation Camaro", by the way. They didn't complain with the 305.