1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

12a lungbutter + sweet smell

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Old 05-12-12, 09:00 PM
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12a lungbutter + sweet smell

Before you tell me to go read, I have, I just want to verify this.

Crankcase pressure is too great, need to vent it because it's sucking in coolant, right?



The solution is a vent where you fill the oil, correct? My specific question is, do I need to change this because I am not running any emissions and I am not running a stock Nikki carb but a Mikuni PHH 44mm?

Here are some more shots of the engine bay:







Old 05-13-12, 07:44 AM
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Originally Posted by Shrimp
Before you tell me to go read, I have, I just want to verify this.

Crankcase pressure is too great, need to vent it because it's sucking in coolant, right?



The solution is a vent where you fill the oil, correct? My specific question is, do I need to change this because I am not running any emissions and I am not running a stock Nikki carb but a Mikuni PHH 44mm?

Here are some more shots of the engine bay:







Where is the sweet smell coming from? Your oil filler tube? Your exhaust? Does it smell like maple syrup?

I'm at work and can't see the images so I don't know what your setup is like, but Coolant will give you the sweet smell.
Old 05-13-12, 08:14 AM
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what is your little rigged up deal with the plastic bottle in the 3rd picture all about? It looks like you have manifold vacuum hooked up to it.....
Old 05-13-12, 10:58 AM
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Originally Posted by 82FanTC
what is your little rigged up deal with the plastic bottle in the 3rd picture all about? It looks like you have manifold vacuum hooked up to it.....
It's an overflow for something, I am not positive what it goes to though. I bought the car track ready and have only modified it slightly (ripped out the interior and put the new carb on). THe manifold vaccum is hooked up below that line.

The sweet smell is coming from the exhaust, whenever I rev the crap outta it is when I smell it.
Old 05-13-12, 11:15 AM
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the stuff in the oil filler is condensation.
Old 05-13-12, 11:28 AM
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Originally Posted by j9fd3s
the stuff in the oil filler is condensation.
So I should get a crankcase vent right? Or so the FAQ says I should, or use a PCV valve but since I have no emmissions I figured vent would be easier.

My question is, since I am running a different carb do I need to change the position of the vent on the block?

I know with my 09 GT, which has a oil catch can on the vaccum side of the intake, would need to be swapped to the other side if I were to go forced induction. Granted, this is just a carb swap and not FI but I wanted to make sure before I did anything and started spraying oil everywhere under the hood through a vent the was in the wrong place.

Here is a video of the current state of that car, it's still a work in progress. Also gave it some throttle abuse once it was warm to show you guys where/when I'm smelling it. At the end of the video I do some engine revving, after that there is a sweet smell. It doesn't occur unless you really increase the RPM, 5-6k or below and it's not nearly as apparent if you can smell it at all.

http://www.youtube.com/watch?v=TIwvug-cups

Last edited by Shrimp; 05-13-12 at 11:36 AM.
Old 05-13-12, 12:13 PM
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Originally Posted by Shrimp
So I should get a crankcase vent right? Or so the FAQ says I should, or use a PCV valve but since I have no emmissions I figured vent would be easier.
yes, the oil gets hot and then can condense the water in the air. the carb you pick shouldn't matter at all, but a turbo will want one side of the PCV in front of the turbo
Old 05-14-12, 07:54 AM
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Originally Posted by j9fd3s
yes, the oil gets hot and then can condense the water in the air. the carb you pick shouldn't matter at all, but a turbo will want one side of the PCV in front of the turbo
So by venting the crankcase I am doing what exactly? Getting fresh air inside the crankcase quick enough that it doesn't have time to condense?

Also how does hot oil condense water? I thought cold things condensed it. Maybe it turns water into vapor and then when the engine cools it condenses?

Sorry if this post sounds a little arrogant or that I am in dis-belief, trust me I am not. I just want to understand the process better since I want to maintain the car as much as I possibly can.
Old 05-14-12, 09:16 AM
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Slightly off-topic, but that calibrated twig connecting the two vacuum advances on the dizzy together isn't doing you any favors. If you're not going to use the vac advances, you should just take the hoses off them.
Old 05-14-12, 09:51 AM
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Originally Posted by DivinDriver
Slightly off-topic, but that calibrated twig connecting the two vacuum advances on the dizzy together isn't doing you any favors. If you're not going to use the vac advances, you should just take the hoses off them.


Not sure what you mean.

The tubing connected to the UFO lookin things in this pic?



Sorry if I am a bit behing in my rotary knowledge, I have had this car for about 2 years but I haven't had a chance to sit down and work on it, I did keep it running well in the interim though, started it and ran it every now and then.

Last edited by Shrimp; 05-14-12 at 10:02 AM.
Old 05-14-12, 09:54 AM
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Originally Posted by Shrimp
So by venting the crankcase I am doing what exactly? Getting fresh air inside the crankcase quick enough that it doesn't have time to condense?

Also how does hot oil condense water? I thought cold things condensed it. Maybe it turns water into vapor and then when the engine cools it condenses?

Sorry if this post sounds a little arrogant or that I am in dis-belief, trust me I am not. I just want to understand the process better since I want to maintain the car as much as I possibly can.
well actually we should go the other way, its not a head gasket, or a bad water seal. there is a freeze plug in the front of the engine, but other than that getting water into the oil in a rotary is impossible, so the lung butter is just a nuisance.

even stock cars do it, Rx8's do it. somehow, the heat from the oiling system can condense water in the oil filler neck....
Old 05-14-12, 12:01 PM
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Originally Posted by Shrimp
The tubing connected to the UFO lookin things in this pic?
Yes; the UFO-looking things are vacuum diaphragms that operate the timing advance for your ignition system - - they advance the timing as vacuum increases .

Normally, they connect to a vacuum port on the carb, but as you don't have a standard carb, they seem to connect to nothing. Plugging the lines kind of works against you; if they're not used (like when the distributor has been locked) you generally just leave them open with no hoses on them.
Old 05-14-12, 01:04 PM
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Waffles - hmmm good

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Originally Posted by j9fd3s
well actually we should go the other way, its not a head gasket, or a bad water seal. there is a freeze plug in the front of the engine, but other than that getting water into the oil in a rotary is impossible, so the lung butter is just a nuisance.

even stock cars do it, Rx8's do it. somehow, the heat from the oiling system can condense water in the oil filler neck....
When the engine gets hot any water in the oil or air gets vaporized into steam that
rises to the highest point in the crankcase ( the oil fill tube ). It cools there and
condenses out leaving water and whatever it carried up there on the side of the
tube. The gunk is probably some of the solids from the oil that also has vaporized.
The combination leaves a gooey, waxy kind of mess in there. This is my best guess
anyway.
Old 05-14-12, 01:15 PM
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Originally Posted by DivinDriver
Yes; the UFO-looking things are vacuum diaphragms that operate the timing advance for your ignition system - - they advance the timing as vacuum increases .

Normally, they connect to a vacuum port on the carb, but as you don't have a standard carb, they seem to connect to nothing. Plugging the lines kind of works against you; if they're not used (like when the distributor has been locked) you generally just leave them open with no hoses on them.
Hrmm... There are ports on the carb that I don't have anything going to, but only because on the exploded view of the carb they either aren't there, or they are listed as "plugs" and not "ports" so I capped them off thinking someone modified the carb to their liking.

I may not have everything I need hooked up properly.

The two ports I am talking about are on the bottom of the carb, right before the butterflys.



It is the two ports capped off with the black rubber caps.

Also, after taking a second look, the oil filler tube has a port on it, connected to a line that is connected to a resevoir with an air filter on it. That should perform the same function as a vent should it not?

You can see the oil filler port in this pic:



And the black res with the air filter on top is what it connects to.


Last edited by Shrimp; 05-14-12 at 01:22 PM.
Old 05-14-12, 03:49 PM
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Looks like the filtered canister is being used as an oil catch, an they used the normal fuel-return-line one-way valve (little silver cylinder) as a sort-of PCV valve.

Afraid I can't tell you anything about ports on the side-draft - - I'm a Nikki guy. But others here may be able to tell you how to connect vacuum advance to a side draft.
Old 05-15-12, 10:17 AM
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Printed out the manual for the Mikuni PHH, I guess it's time to read.
Old 05-15-12, 01:18 PM
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I've read through the manual and there is no mention of hooking anything up other than a fuel line a starter cable and a throttle cable.

The previous owner said he had built it for SCCA Spec RX7 racing and according to the journal he kept that I am going through right now it's been built for that.

Tokico blues, sway bars, front suspension bushings for control arms, tension rod, and idler arm.

He modded the front strut towers by cutting them to all for some more camber/caster (sadface... I wish he wouldn't have). Removed the rear rubber seat spring it looks. I am just going by small checks he put next to the rules, I am guessing he was marking what he changed.
Old 06-30-12, 03:14 AM
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I love RX-7s

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Originally Posted by Shrimp
The sweet smell is coming from the exhaust, whenever I rev the crap outta it is when I smell it.
I love that smell. Does it smell like race fuel? If it's strong, it might be from a premix left in the tank? Some of them make the exhaust smell "sweet" - though I find even stock motors produce that sweet smell.
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