787 RFI Rave Valve ??

[Gasngo]

Good morning. Im getting things in order and diced to pend a few minutes working on the RAVEs . When I pull a vacuum on them 1 leaks a bit but slowly rise back to open. Then I actually started thinking about the operation and Im a little confused. I have read about them where exhaust pressure opens them I guess older carbed models but seem to be thrown off by the RFI. It would appear if vacuum is supplied then they are closed [or down and all the way in] and no vacuum they are out even against the spring tension. Any input is welcome. While its on I would like to have it set up correct.

 

[Gasngo]

Ok I have educated myself a bit. I have cleaned the blades but never took the diaphragm apart. So 2 springs 1 under and larger on top. Cleaned things up and appears to hold vacuum. But my error when you install the outer spring and cap it does seat the blade and I assume the exhaust pressure opens it or does it get boost pressure from the RFI? also.

 

[etemplet]

If the raves hold pressure and you have them assembled correctly you then have to inusre the rave selonoid if functioning properly and that the check valve to the engine block is holding. Air pressure opens the raves, absense of pressure and the springs should close the valves. I've ridden an RFI with the rave air line disconnected. As one might expect the raves were sluggish but worked to a degree.

 

[Gasngo]

Well but it on the water last night and it ran pretty good. After a hour or so with throttle variation laid into briefly and the mid range throttle was impressive. So I dont think I need to do anything other than get more seat time and maybe a impeller upgrade next summer. I have a couple ?s but will start a new thread thanks for the input. Ill post some compression numbers a little later.