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Recently got the car, a 68 Firebird with a 71 400 GTO engine "YS" transplanted. Compression on the engine measured as follows, the first number is dry and the second number is with a half a teaspoon of oil added. All plugs were out and throttle wide open during testing.

cyl dry wet

1 146 160
2 152 153
3 150 151
4 145 146
5 154 170
6 159 164
7 150 151
8 154 160


Cyl 1, 5 bumped up quite a bit higher with some oil added while the others didn't show much difference. The readings seem to be close to the shop manual range 0f 150-170.

I'm wondering if this engine is in need of rebuilding before gettomg other work done to the car. It's not running well. The ignitions wires look old and questionable. The carb need to be sorted out too. It has a vibration peak at around 2500 rpms and odor of raw fuel

I have no idea how many miles the engine had on it when swapped into the car or how many miles afterwards. There is plenty of varnish and deposits under the valve covers.
 

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Usually cylinders should be within 10% of each other. You are right at that point. It is up to you. Do you feel like rebuilding it? Is a fresh new engine worth the trouble? If so start making arrangements. There are a lot of nice engine kits on Ebay for cheap.
 
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