SX/SXi/SXi Pro Does engine compressioin increase after break in period?

H

halojmpr20441

Location
North Carolina
I have a 92 SX 750, just rebuilt my top end (now bored to 80.50 mm) using SBT pistons and rings. I installed a ADA racing head using 28cc domes (should have my motor at 180 psi). Keep in mind my motor has NOT yet been ran with the top end. My compression right now is only 153 psi and 160 psi. Is this normal and will the compression increase after break in and if so how much, or if I want 180 psi, should I go with a smaller dome size? Please help if anyone knows. I was told not to run more than 180 psi on stock bottom internals, which is what I have and I'm afraid if I go ahead and get smaller domes to increase my compression, my compression might be above 180 psi after break in. Does anyone have any suggestions for me? Thanks, Scott.
 
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Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Yes, it will increase some.

To get accurate compression numbers, you must have the following:
- good, fast starter
- good battery
- good cables
- known good and accurate compression gauge
- hold throttle open while testing
- compression fitting in one hole, spark plug in the other.

ground your plug leads
 
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Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Please stop posting this thread everywhere. I've moved this one to the appropriate section.
 
Matt_E

Matt_E

steals hub caps from cars
Site Supporter
Location
at peace
Anytime you're cranking the engine over and the plug boots are not connected to installed spark plugs
 
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