NanaimoRx-7

Okay, I've spent most of my weekend here looking for the thread, and my best guess is that it's gone. Would anyone mind restarting it for me, I know there are others who are interested too. First problem; the oil filler neck, what to do with the two hoses? Plug them, re-route them? The vacuum advance has been disabled on the car, but do I plug these hoses back at the carb? It would be really appreciated if the people who have done this could lend a hand to a guy who doesn't give a rat's *** about emissions. Hehe, if we ever get emissions testing I'm screwed. Oh, and on the topic of emissions, I never bothered to get the block off plate for my ACV, what problems does this cause? Thanks alot guys.

Rich

I can only answer the vac advance question....

the vac advance works by advancing the timing when vac is lost. there is no reason you can't block the line with a golf tee, or if you want to go super high speed, you could weld/crimp the vac line nipple on the carb. I would just plug the line, or route it to something useful/ricy maybe a vac guage?

SilverRocket

I spent a while getting people's opinions and trying to get this right. First off, make sure to keep your charcoal canister. The line from the canister should go to the crankcase nipple (on the middle housing near the base of the filler neck). Next thing, get a small "breather filter" and put it on the nipple on the oil filler neck. Don't plug it! This is the only setup that I've tried that eliminates condensation and oil slime in the filler neck.


Plug all the hoses at the base of the carb, but do not plug the vacuum pots on the distributor.

Also, there is a large hose going from the nest to a large nipple near the top of the carb. This is a vent for the carb and must be left open. Do not plug this one.

You'll probably have more questions as you go along with this... I know I did lol.

REVHED

Huh? What do you mean by "when vacuum is lost". The vacuum pots on the dizzy advance the timing when vacuum is present not when it's lost. Or maybe I just misunderstood what you said.

SilverRocket

First off, don't weld/crimp anything, it's a real bad idea because then you can't put anything back. The best way to plug vacuum ports is to go to any auto parts store and buy a bunch of rubber vacuum caps, they're cheap and work well.

Secondly, vacuum advance works by advancing the timing when vacuum is present, ie. when your car is idling. Think about it, the engine is trying to suck in more air but the throttles are closed, hence vacuum. During wide open throttle acceleration there is no vacuum advance. It is an emmissions feature that promotes combustion in the catalytic converters, back when you had them. It has absolutely nothing to do with performance or power. You'll find that you idle a little smoother without it, and it will be a little less confusing to set your timing.

Keaponlaffen

If I'm not running cats then, I can remove all of my vacuum advance crap? That'd be nice... it'd really clean up my engine bay. What things does vacuum actually control? What would happen if I removed it all completely? Would my carb's secondaries not open? If anyone has a diagram of what I can remove, it'd be great if you could post it... Thnx

Jeff

'79 RX-7 GS
Power Nothing
No Cruise
Nothing luxurious,
Just raw 12A power
and a damn manifold.
(but no cats or presilencers,
or smog crap that robs HP)

NanaimoRx-7

Well, I got a bit over excited today and just went for it. I started ripping everything off and capping it at the carb. It came off fairly easily and didn't take too long. I've taken the hose from the charcoal canister, the other hose that T's onto the emissons rack right next to it (same size) and the nipple from the crankcase and joined them all together with a plastic T. The tube that comes off the oil filler neck goes to plastic dashpot looking thing (real technical stuff here, huh?), and has a small hose coming out it which looks like it goes back to the fuel tank. This is part of the evaporative system right? I capped the top tube and left the return line alone. When I went to start it I came alive fine, but then reved up and died. It ran like ****, I had two wedge a quater behind the choke just so I could get out and mess with the adjustment on the carb. I couldn't get it to idle under 1500 RPM, the I finally saw the problem ( well actually I heard it).

I now know what the point of gettin an ACV block off plate is! The only thing it did before was impersonate a blow off valve, now it's continously open which creates a vac leak the size of my thumb. Booo, this sucks! I fabbed a plate out of some 1/8" metal I had, but the seal isn't great. Anyone know where I can find one faster/closer than Mazdatrix? So now I have it running hella rich to compensate, I started out waaay too rich, it was popping blue flames out the back just sitting there. It sit around 1000 RPM, but it's shaky as hell. Do you think I could get a local metal shop to make the plate for me?

P.S. REVHEAD, I'm pretty sure you're right on that one. That's the way I heard it too (Yaw). Easy to get it backwards. Thanks for the quick replies guys.

SilverRocket

Your secondaries will still open, that system has nothing to do with the rat's nest.

You don't need a diagram, you can remove the whole rat's nest and all the vacuum lines, the only vacuum line you really need to keep is the one for the brake booster, and also the one from the charcoal canister to the center housing.

NanaimoRx-7

Uh-oh...brake booster? Which one is that? I don't think I took it off, went around the block with no problems. What about the line that comes off the gold colored solenoid mounted on the side of the carb facing the left front wheel? It was originally on the same line as the charcoal canister and the intermidiate housing does it not also need to be kept? Thanks George

Yeah, that's what it looks like....

SilverRocket

Nanaimo,

I don't think what you did with the PCV system is right... as far as I understand that dashpot is just a vacuum switch which acts to relieve fuel vapours when the car is shut off. But the way you've hooked it up there is no fresh air in the mix and I believe you'll get condensation in the system. I'd recommend you just run the canister to the center housing nipple, and then put a filter on the oil filler nipple. I'm sure there are other ways to hook it up, but I know for a fact that this method works very well and is what most people recommend.

I have the Racing Beat ACV block off plate on my car. BTW, I also removed the big air pump solenoid thingy on the passenger side of the carb (the one with the big vacuum line connected to the intake manifold). You don't need that anymore. Ditto the hot start assist system if you like.

Pulling off **** is fun

Keaponlaffen

Is there any way to remove the little things that the vacuum lines plug into on the distributor and on the carb? I think they're diaphragms, but I'm not sure... They're metallic.

Jeff

SilverRocket

You wouldn't have removed it, it's not part of the rat's nest system. It is the big vacuum line that goes onto the black brake booster on the driver's side firewall. You need the vacuum line in case your car stalls while driving - if the line isn't connected, if would be very hard to stop in this situation. If it is connected, you'll have enough brakes for one stop or so.

Sorry I'm not too sure about this one... let me go check my car!

SilverRocket

Alright just had a look - My charcoal canister line isn't hooked to anything like that... just a line from the gas tank and a line to the center housing.

I think various model years of Sevens were set up a little different. Mine's an 82, what about yours? You might want to check the Haynes manual to figure out how your system works.

Anyone that has this mysterious gold solenoid wanna chime in?

SilverRocket

Why would you want to? I personally wouldn't do anything you can't put back if you need to.

NanaimoRx-7

I wouldn't remove the diaphrams on the dist. If they are disconected, they are not sensing any vacuum therefore not making any difference to your performance. However, the trailing diaphram (the one closer to the left fenderwall) is responsible for the adjustment of the leading/trailing split by loosening the two screws on the top and sliding it in and out. Removing it, I'm sure, would mess up alot of stuff. And don't mess with it until you get a timing light. Don't have one? What's a better excuse for you to go buy a new tool than that? Hehe, I'm just waiting until I have to jack up the car again (guaranteed to happen in a couple weeks), so I can go buy a jack like they have at shops.

SilverRocket

I just clued into that he wants to remove the actual vacuum pots... no no no bad move. Don't take those off your distributor. There's a few things that don't need to stay on your carb, but if doesn't hurt to leave them on either.

NanaimoRx-7

YEEEESSS! I found my Hayes manual, it was hiding under my desk (at my feet the whole time ). Okay, starting at the charcoal canister, the line comes out and meets up with a line from the Air Vent solenoid (mysterious gold solenoid) and continues to the center housing. The other line from the oil filler neck goes into the Ventilation and Check valve which goes in three directions, one to the gas tank and 2 to the carb (Altitude and Idle compensators). Hayes Manual pages 97 & 103 I have a 1980. Wow looking at the other diagrams it's lucky we're speaking the same language SilverRocket. How many solenoids did you have? I had 3 but I see the later models with 6! Also they don't have the Mysterious Gold Solenoid (I think it adds 46 Hp !) and the charcoal canister actually looks like a canister. Mines in the Air Cleaner lid. Oh well, it looks like it'll all work out when my plate from Racing Beat comes (Ordered it tonight, yaaay). 6$ U.S. hmm... sweeeet I'll have enough change from that $100 Bill to buy a beer!

Rich

sorry momentary lapse in brain function... it's been too long sence I have had a distrubitor. I must admit, I do love DIS

SilverRocket

Hahaha... that point rings clear to me since as we speak I'm writing a 40 page research paper on CAN/US exchange rate determination and real interest rate differentials. It was due today but only 2% per day late penalty lol

Sounds to me like you've got it pretty worked out. Just check your oil filler neck after a few days to see if you get a bunch of condensation and slimy crap. You'll know what I mean if you see it... it'll rust the inside of your filler tube if you let it persist. I think you're gonna be ok though, because you have the line going to the air cleaner worked into the system.

Good luck!