Insane rx-7

iTrader: (1)

Hey guys,

I have been trying to figure this problem out FOREVER. My car doesn't smoke at idle or normal driving. But when I take it to 7,000 rpms and shift or decelerate from 5,500 + it dumps white smoke out the exhaust. I read that lung butter can cause this. So I hooked up a pvc value and vented the crank case. Problem still exists even after an oil change. I was premixing the gas. So I thought, it might have been that I was putting too much oil in. I hooked the oil metering pump back up and after two tanks of gas it’s still doing it. Coolant levels never drop and as far as I have been told it’s nearly impossible to burn coolant on a rotary. So my conclusion is that its unburnt fuel. I changed my carb from a holley 500 which never ran right BUT never threw white smoke. To a modified Nikki. Could this modified Nikki be so bored out that there is just way to much air for the jets in the nikki to keep the ratio correct? I am running an msd box with 8.8 mm wires, direct fire with 3 msd coils. 90Amp alt. Holley blue pump at 4.5psi. Might I need to increase the psi? Or decrease it? I have tried playing around with the idle mixture and air screws and I can reduce the smoke a bit but not eliminate it. I either have tons of power - lots of smoke or no power and just a smoke cloud.

I could really use some insight so that I can get this problem solved. Because I believe is solvable. Also the carb was modified by Rob from Rotary Shack.

Also forgot to add car has NO emissions at all. Not even a cat.

Zackqw

now this could be a hard one to solve.. my only question i have atm is, when it smokes are we talking about like a honda smoke?(enough to not see behind you?) and also, do a oil flush but instead try adding really thick oil (10W40) or so..

1stGenJake

It is, but maybe not in the way you think.

Coolant seals can go bad and leak on the intake. Freeze plugs solve the problem. Maybe not your your problem but I had the same thing happen to me and when I took the intake off to inspect... whaddaya know. The O rings were wrecked to the point of unrecognizable. New freeze plugs and no one behind you swerving out of the way.

-Jake

orion84gsl

iTrader: (5)

My engine was doing this as well and my assumption was that the oil control rings were destroyed and allowing oil into the combustion chamber.

jshiz

iTrader: (4)

Vtec kicked in?

tasty danish

iTrader: (5)

Who told you you can't burn coolant in a rotary? Coolant seals are not in the intake. There is an o-ring from the rotor housing to the intake, but that is not a "coolant seal" as people refer to them. Coolant seals keep coolant from leaking into the combustion chamber, it's the reason you NEVER EVER overheat a rotary.

Anyway, if you pull your radiator cap and can see bubbles that's a bad sign when it's running. Sometimes when you get a coolant seal leak, you won't loose coolant, you may appear to gain it as the pressure pumps coolant into the overflow. Have you caught a whiff of the smoke? And it is pure white, not grey or black?

Insane rx-7

iTrader: (1)

I was thinking about this last night. I think its got to do with timing. When I installed this carb I was also testing timing options. I will place everything back to the original specs and see if that fixes anything.

And I know about the O-rings in the intake where coolant can get into the combustion chamber. But why would it only do this at high rpms? If it is leaking there I should have smoke all the time.

tasty danish

iTrader: (5)

yeah that wouldn't be the case, but if it's the coolant seals in the combustion chamber, the pressures at high rpm may be enough to leak them but not enough to do the same at low rpm.

What seems more likely to me though is the path you are pursuing. Set to stock and report back.

Insane rx-7

iTrader: (1)

Adjusted the timing and added Vac advance and well no smoke now lol. Just have to play with the carb now because I set everything back to scratch. But seems like retarding the timing fixed this problem. Thanks for all your suggestions guys!

Kentetsu

When you let off at high rpms, it creates a vacuum that can be strong enough to pull oil through the oil control rings if they are worn. I had this problem with my old motor, and it was pretty severe. It started when I accidently overfilled my crank case during an oil change (Haynes manual only gave correct amount of oil in the appendix).

I replaced a quart of oil with a quart of Lucas Heavy Duty Oil Stabilizer and it eliminated 95% of the problem. Definitely got me good enough that I didn't have to worry about it.

For a good example of what worn oil control rings look like, click on the link in my signature (autoX videos) and check out the Tail of the Dragon video. There is a section where I'm following Orion (who posted above) and whenever he lets off you can see the cloud of smoke produced.

Hope this helps. I'm glad that it seems to be better since you changed the timing, but since that doesn't make sense to me I'm betting you'll find that you still have the same issue.

Also, somebody recommended doing an oil flush. Do yourself a favor and stay away from anything like that. It will produce problems, not solve them.

And you may already know this, but a can of Seafoam through the gas tank every couple of months keeps the compression and horsepower up.


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Insane rx-7

iTrader: (1)

I watched the video you suggested I watch. What your saying makes sense but the motor was just rebuilt, its only got like 26k on it. So I guess it wasn't put together properly or something. I will try the stabilizer on my next oil change and see if that makes any difference. Thanks for the suggestion.

Also, from what I saw in that video. My car was like 100x worse then that. That GTR would have been completely covered in smoke for a good 10 feet lol and it would have floated there and stayed. But since I adjusted the timing and carb and stuff its about maybe 1/8th of that smoke if i pull it to like 8,500-9,000 rpms. That doesn't bother me because I usually always shift at about 7,500.

orion84gsl

iTrader: (5)

It got to the point that I just didn't care anymore and would hold 2nd gear to 8K at autocrosses. Now that was a smoke show. How shocked was I when the engine finally let go.

risingsunroof82

iTrader: (3)

Kentetsu..... i have heard that seafoam is not a good thing to run in the rotarys. So what exactly is it doing in there? And you just mix it with a tank of gas? I thought it smoked REAL bad when using it too? HA! lots of Q's...

Kentetsu

No, Seafoam in the tank is fine and does not smoke. Dump it down the carb, then you get the big show and waste all of the Seafoam.

Insane, you must have looked at the wrong part of the video. It was not my car smoking, but Orion's when I was following him (on the screen it says "cough cough cough")

Also, make sure your oil level is not too high!!!!!