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-   -   Compression/Idle question (https://www.rx7club.com/rotary-car-performance-77/compression-idle-question-123760/)

DavidDeco Oct 14, 2002 10:21 PM

Compression/Idle question
 
I had my engine rebuilt a few months ago. It has about 2k miles on it now. 3mm apex seals and a streetport.

My idle holds steady now, my vaccum at about 900 rpm is 16" which I thought was good.

My compression check however is terribel. The rear rotor runs 6.3, 6.4.6.5. The front rotor is like 5.8, 6.3, 7.1. Extremely low and on the front not even.

The compression was similar when it was first checked and the guy promised to rebuild it for free (I believe him on this) if it didn't come in line after a few k miles.

If my car is idling steady, has pretty good vacuum for a streetport, what do I have to worry about for these numbers???? I have not taken it to a dyno yet because of other issues that may now be resolved. Hopefully within 2 weeks I will do so.

Thanks!

Scalliwag Oct 14, 2002 11:07 PM

If your readings are accurate I would have him pull it back apartwhile it is still under warranty. Since it is a street port you are expecting some lope. The harder thing to distinguish is how much lope is from the porting and how much is from erratic compression?
What you have to worry about is if these numbers start getting better or not.
If the seals are as seated as they are going to get then you have trouble.
A couple of questions I have. What seals are you using/ What brand of seals/Who cut the rotors/How much clearance is between the apex seals and the freshly milled slots? There are actually more questions I could think of. Like what kind of shape are the rotor housings in?
Bottom line without seeing the car and monitoring it , it is in your best interest to get it back down.
You need to run compression checks at intervals. Out of curiousity check it after it is first put in and then after a few hours of driving. Then about once a week. Sometimes they take a while to seal. But if the numbers are that far out it sounds a little risky.


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