Hi, I have an 87 non turbo and ever since i bought it I have had a flat power curve after 5000 rpms. It kinda does little tiny cut outs but still has a little power. Its almost like the compression on one of the rotors is bad. I checked both rotors with a normal compression tester and got a perfect 85psi, but i didnt have a special tester that somehow tests the back apex seal. Do you guys think its a blown apex seal. I have a carb manifold on it and I believe the car is runnin too rich, so could this be the problem? I got new spark plugs because the old ones had black residue (probably from running too rich) but i didnt notice any difference. I am getting a new intake manifold and a header soon. Is there any way that by not running as rich this would fix the problem, or should i plan on buying a new engine? Also where can I buy a compression tester for a rotary? Thanks!

 

[QUOTE]Originally posted by chris_stampe
I checked both rotors with a normal compression tester and got a perfect 85psi, but i didnt have a special tester that somehow tests the back apex seal. [QUOTE]
If you checked the compression, you should get three hits of comp not just one. Take out the schrader valve, and retry the compression on both rotors. The three hits should be very close to each other, 80-80-80. If you have a bad apex, it will compress like 0-0-80. If you have a bad side seal, it will compress like 0-80-80.

Are your 5th and 6th ports stuck open?

 

If it runs smooth, idles OK and doesn't belch out smoke then your seals are 'probably' OK. I'm confused about your 'carb' manifold ? do you mean you are running carburettors instead of fuel injection? If this is the case then it is quite possible you may have the wrong jets, or more likely the venturis are too small to flow the air needed at these revs. It is a pretty specialised skill to set up carbs on a rotary, but if you still have the O2 sensor then an A/F meter will indicate if you are running rich.

 

Yeah, I have a 2 dual barrel carb setup on it now. The jets probably are wrong, so I am going to get a whole new intake that is already jetted properly and sell the old one instead of messing with it. The car idles high but fine unless its cold. Small amount of burnt oil, and it shakes a little at start up and is hard to start when cold. I dont think the apex seals would be completly blown, but could they be just worn>??? Thanks for the help.

 

Get the carb(s) properly tuned. Also, make sure your fuel filter is clean. Look at your spark plug electrodes. If they are black and you can smell raw gas on them, then its running rich.

 

The aux ports being stuck open won't cause lack of power over 5K because they're supposed to be open by then.
It sounds like the main jets are all wrong or the carb's just too small. What kind of carb is it? Weber? Del'Lorto? What size?
Unless it's physically too small, replacing the whole setup with another carb is a very expensive (and silly) way to fix this prob. You'll have to get the new one tuned anyway!

 

Probably too rich- Most people think low power at high RPM's is leanout- but the majority of time it is overfueling.
Do you still have the o2 sensor?
Check the voltage off of it- if it is over .94 or so at full throttle, you are over-fueling.
To get hesitation from leanout, you have to be running REAL lean. Probably not.

 

Well the reason im getting a new carb system is because some guy will trade me for the old one for a new one and throw in a header. Ive got an old one that is pretty rare and the carb is made to work with a turbo which I dont have the parts to put one in. I do still have the O2 sensor so I will check it. As for a new fuel filter, should I just buy a universal fit one off of ebay or is do I need a special one? Thanks for your help guys.

 

I meant to say stuck closed...just like mine are.

 

Get yer car running right before adding mods =) could only complicate things...