Gatorgunner

Alright, so im thinking about yanking this fu--ing thing out. Heres my question:

Can I patch the hole by covering it with a peice of metal from a soda can or something, or do I have to go to the hobby shop and buy a peice of sheet metal?

Is there pressure behind it, or vacuum, etc?

What about fuel in constant contact?

The usuall questions, but basically, what can I get away with covering it with?

Thanks for the input

Pedestrian X

id just make a blockoff plate from a peice of 20 gauge

CrazyJoe12a

i filled the holes with JB Weld

Strider

I had half considered doing this myself, and I think that JB weld would work just fine, but I noticed something on my 85 GS:

The manifold inner diameter is slightly larger on the throat that has the shutter valve in it. I guess that this was done to compensate for the cross section of the valve so there is equal flow to the front and rear rotor. So by removing this, you then have more flow to the rear rotor than the front yes? More flow is generally good, except I should think that you want equal flow front and rear.

So I just blocked off the hose to the air cleaner. That cross section is compensated for with the larger inner diameter, and if anything increases turbulence in the flow which is good for the fuel/air mixture.

MIKE-P-28

iTrader: (1)

on mine, I used a bolt to cap the holes, and the center shaft, I used a carriage bolt, and the outside i used a nut/and a thrust washer. Plus I sealed the **** out of the hole before I shoved the bolt through, so It couldnt come out...

MIKE-P-28

iTrader: (1)

See the opening in the top of the manifoild taht joins the 2 ports together, theres your compensation, yank the POS out, it will be fine, I did drove it to 224k miles

Gatorgunner

cool, thanks everyone

Lt. Dan

Um, what's a shutter valve? How does it help performance to block it off?

Dan

MIKE-P-28

iTrader: (1)

Shutter valve is a nasty little device that under decel conditions, completly closes a flap in the intake manifold cutting off all air/fuel mixture to the rear rotor... Its suppose to clean up the emissions buy burning the rear rotor with nothing in there but excess gas... Total POS, and considering 80% of all rotarys going bad are the rear rotor, coincidence or fact>?

Gatorgunner

So there is no problem using a peice of metal from a soda can with JB Weld?

Keaponlaffen

You're sure you're talking about the Shutter valve and not the ACV, right? Just a dumb question.... 'cause the shutter valve shouldn't need a tin can to cover up... just a couple of holes to fill in with screws/jb weld/whatever...

Jeff

12aPwr

sorry to sound newbiesh but where is the shutter valve located? and does anybody have any pics? i would wanna do the same thing

85RX7GS

iTrader: (1)

LOL. You might want to try putting a bolt in there and put some silicone on each end that sticks out.

MIKE-P-28

iTrader: (1)

Shutter valve is visible by looking at the rear of the carb from the drivers side, its way down at the base of the carb, under all the emissions ****...

MIKE-P-28

iTrader: (1)

**** no, use something thick at least 1/4 inch alumnimum LOL I think the RB ones are steel which I find to be over kill..Well thats for a ACV valve not the shutter

all the info you ever wanted to know about the **** errr I mean shutter valve

http://www.mazdatrix.com/FAQ/SHUTTER.HTM

Stripgear

iTrader: (2)

Here is a picture of the shutter valve.https://www.rx7club.com/forum/showth...=shutter+valve

Suparslinc

If anyone was still wondering, you need to remove the intake manifold to remove the shutter valve. Otherwise, you might drop one of those little tiny screws into your engine and that would definately be bad.

Now going completely against what I just said, I'm going to try and wedge a shop rag underneath the butterfly, so it catches the screws in case I don't. If it still looks risky, I'll take the manifold off; not much more work considering you have to remove the carb either way.

Strider

Well, that opening will equalize pressure, but won't necessarily equalize volumetric flow rate. Recall that flow will take the path of least resistance, and for the flow to go through the knock out into the chamber that is slightly more constricted I find unlikely. Probably not that big a deal, but all the same, so long as there is no possiblility of that valve closing on its own, and there is no leakage around the shaft, then I don't think its that big a deal to just leave it in there disabled.

BTW, I think that the difference in diameter is about 1/8" inch, maybe less. I wish I had done some measuring with my mics when I had the carby off. Considering the venturis are the same diameter, then the difference in flow resistance shouldn't be that great. Maybe Sterling could bench flow test it.

Gatorgunner

cool thanks guys

Gatorgunner

Woooo hoooooo over 100 posts, i can have a kick *** pic now as my avitar

jayroc

Well, I can tell you what happened when I changed my shutter valve. The problem was it was making some strange chattering noises as outlined in that mazdatrix article. So, I thought I'd like to keep it stock and bought all the parts necessary to do a swap. (ie, throttle plate, shaft, valve, gasket) I checked the shaft and decided it was okay (and I was too lazy to take off the intake manifold anyway) and replaced the valve... Easy enough. MOST of the chattering stopped, but on decel, the valve would still chatter and still wouldn't close sometimes at idle. Irritating. I figured it was the shaft or too much play in the throttle plate. So, I then went and took off the carb and tried to replace the shaft. Well, GOOD FRIGGIN LUCK gettin those screws out of the shaft. I sure as hell couldn't do it without takin the manifold off. Even, then, I doubt I could. Maybe with a torch or something....
I'd just plug the vac lines for it if I were you. That is what I ended up doing. Doesn't chatter anymore.

BTW, Mike. I'm using your vac line plugs on my 84 now. Still works.

Maguire

iTrader: (1)

Im not real sure how this valve works, so i gotta ask a question. First this is why im asking. Im about to but my racing beat exhaust, and when i do so im going to remove my emmsions componets. Will plugging the vaccum line to the selinoid have the same effect as removing it? Meaning will it leave the butterfly open all the time? Or is there a chance that it could get stuck shut at some time?


(sorry gator gunner, i hope i dont hi-jack you thread)

Gatorgunner

nah you didnt hi-jack it at all.

I have my shutter valve line pluged, and it stays open. But My valve, I think, is stuck open anyways. From what i gather, if you plug the big hose from the shutter valve, and leave the little one open, the valve will stay open.

Hope that helps man

Strider

The danger is from that 1/2 inch rubber hose that runs from the air cleaner to the shutter valve. If the shutter valve diaphragm fails, then that line can act as a flow bypass from the air cleaner straight into the intake manifold without going through the carb, in other words a big vacuum leak. I plugged that line to the AC, and now there is no more problem. I suppose that I could also plug or crimp that vacuum line from the solenoid, but I would hesitate to remove it unless you cap both ends or else you might have another vacuum leak.

I'm also thinking about wiring or otherwise locking the valve linkage in the open position, although the intake flow should tend to pull it open. But hey, like I said, I don't think its that important to remove it, just to disable it so that it never closes again.

Strider