I just did a rebuild and I don't think anything happened to my RFL. All it does now is make a fluttering sound when I let off the gas. No loud psssssssshhhhh sound anymore. Anyone got any ideas.
Mark
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I just did a rebuild and I don't think anything happened to my RFL. All it does now is make a fluttering sound when I let off the gas. No loud psssssssshhhhh sound anymore. Anyone got any ideas.
Mark
Bad vacuum going to the BOV. If you have it hooked to the small nipple on the turbo outlet, that doesn't work. Have to have good manifold vacuum. If you put a larger cam in you will have less vacuum, then the BOV would need adjustment.Quote:
Originally Posted by show-off
Check if the vaccum line is connected correctly, as in, after the throttle body. If that doesn't help, take the top off of the BOV and dissasemble, and clean, and us a very light teflon lubricant... then just adjust it to once you get it put back on.
STRATMAN: i always thought the manifold pressure signal going to the top of the bov was to help hold the valve closed, not to help the valve open......am i wrong on that?
While under boost there is boost pressing down on the BOV helping it stay closed, when the throttle is realease the motor goes into vacuum which pulls the BOV open releasing the boost in the pipe. The line to the BOV needs to be hooked to the manifold. The vacuum is what opens the valve.Quote:
Originally Posted by Marcus86GLHS
Quote:
Originally Posted by Marcus86GLHS
Do you have that darn check valve hooked up to the thing? If so, take it out, its easy to hook them up backwards...then no pressure vacuum gets to the bov...
"...when the throttle is realease the motor goes into vacuum which pulls the BOV open releasing the boost in the pipe...."
i thought the over-pressure spike within the locked system (ie: compressor is spinning and throttle blade is closed) causes the blow off valve to come off the seat, meaning, vacuum doesnt "suck" the valve off the seat rather pressure spiking within the intake piping pushes the valve off its seat.....i always presumed this because the manifold signal and the spring both act in the same direction: to hold the valve on its seat.
to test this, disconnect the manifold signal going to the backside of the valve entirely and the bov will unseat even when the throttle blade is open.
bov's should only open when throttle blade is closed.
do i have this all wrong?
My type H always used to flutter under light boost. I think you have it shimmed too tight and theres too much pressure trying to close it.
Vacuum pulls the valve open to realease the boost pressure quickly. The boost on the bottom side of the valve (in the pipe) also has an effect on the valve opening, but the vacuum is the main source to open the valve. The spring and adjustment of the pressure release valve (BOV) is intended to equalize pressure release.Quote:
Originally Posted by Marcus86GLHS
Under boost, the pressure in the pipe will want to push the valve open causing a pressure leak in the system, this is where the boost in the line attatched to the BOV helps in keeping it closed under high pressure.
Under vacuum, it simply pulls it open to release the pressure when the throttle blade closes shut, reducing or eliminating a pressure surge.
How tight the valve is adjusted has a huge affect on the BOV causing surge to happen. If the adustment is to tight, it takes a larger amount of vacuum to open the valve causing a noticable surge before you hear the "psshhhh" sound, in that case it can be loosened more to allow a lesser amount of vacuum to open the valve when the throttle is released allowing a faster release of the boost pressure.
I changed nothing on the BOV. It would go off at 3psi or 18psi. It was hooked to the TB nipple before and it is hooked up there now. I am going to put it on my distribution block to see if that changes anything.
I know you had it there before, but I try no to use it as a vacuum source. It seems to not be a very good place for vacuum intensive parts. Try a manifold line, but also try to stay away from connecting it close with the fuel pressure regulator line.Quote:
Originally Posted by show-off
I have a vac distribution block that goes to everything from the firewall. I had one spot left open...now I don't!
Thanks,
Does it work correctly now?Quote:
Originally Posted by show-off
Just drove it. It is audible and seems to work fine. It isn't as loud as it was before. What lessens the vacuum? Just the cam? I had everything ported and opened up. It is also facing up and before is was facing sideways. It goes woooosssshhhh, but the RFL was louder before (I think)
If the cam is off you will have less or more vacuum. Depending on the head work and cam, things can be completely different than before.Quote:
Originally Posted by show-off
Also, depending on how the BOV is facing will make a difference on how you hear it in the car, outside the car it is probably just as audible as before unless it is opening different due to vacuum changes. If you don't hear any surge you may be able to tighten it a little which may open later and result in a louder release of air. When you start to get surge, loosen the BOV a litle until it is gone.
Now with the vacuum at the dist. block, it should recieve more vacuum and open earlier than it used to when it was hooked at the throttle body nipple.
It sounds fine to me. It was so freakin loud before. SOunded like a shotgun. People would duck down at gas stations and stuff!!