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I have a question for all the technical minded people. Stock 87 Sammy with a fresh rebuild on a 1.3L 8V. Swift flat top pistons, head and block decked to clean surfaces. Head rebuilt with 1.6 valves, ported and polished, Delta Cam 272 grind, degreed, and lash at .007/.009. Distributor has been re-curved to provide 22deg advance by 1800RPM. Timing is set at 14deg base with a total mechanical of 36deg. I am, however, still running the stock carb. Wide-band O2 runs 14.6+/- cruise and drops to 12.1+/- full throttle. I have about 1K miles on the engine now, and it still does not seem to be running right. Low power, sluggish, poor mileage(18-20), will barely hold 55MPH on flat ground in 4th (LT215/75R15). Hot compression is only 150 psi, throttle open. Leak down is 3-5% across all. I'm at a loss as to why the compression is so low, and think this could be the power issue. Anyone have ideas on what could be the problem?
 

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I use 92 premium from the name brands. I have moved the timing up to 20, but not much more response/power. I do not get detonation until timing is set at 25 at idle.
 

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If the compression is even across the board I would just let that be for right now. Do you have the stock exhaust? Could be a plugged cat. I would try to track down the over fueling or lack of air. Can you pull off that cat and take it for a ride to see if it improves?
 

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If the compression is even across the board I would just let that be for right now. Do you have the stock exhaust? Could be a plugged cat. I would try to track down the over fueling or lack of air. Can you pull off that cat and take it for a ride to see if it improves?
Thanks to all for the input.

I have the stock manifold, but 2in pipe from there back. No cat just a newer turbo style muffler. The fuel mix is not over-fueling, as shown by the WBO2 sensor. My issue is the compression is very low. According to the FSM I'm way below wear limits on a fresh motor, although they are even.

Standard 14.0 kg/cm2 (199.0 psi)
400 r/min

Limit 12.0 kg/cm2 (170.0 psi)
400 r/min
 

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Discussion Starter #6
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I believe the problem has been solved with a cam change. The Delta Cam regrind is an Isky 272 Clone, and is too big for this build. Usable range was 5K to 7.5K RPM. Valve timing and overlap were killing the motor. After swapping to a smaller cam, the compression is up to 235psi and the power is on par for the build. No issues holding 60mph in 5th up slight hills with throttle to spare.
 
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