<VV> rebuild 140 engine noise

[Michael Kovacs]

 I just started my 140 today after a 6 month partial rebuild. With only 6,000 miles on it, the block was not split . The heads were reworked to reduce the squish height to about .032. The CR was calculated at 9.26:1. The heads have all new valves, springs, guides etc. with only 6,000  miles on them. 
   
   The engine was very carefully rebuilt. I can't believe it could be a piston or cylinder problem. The seats were not loose.
   
   The problem is when I fired the engine it ran for about 30 seconds  at about 1500 RPM and then developed a sharp hissing sound on the left side like a single cylinder compression or combustion leak. It was very evident over the muffler less engine exhaust sound. It was immediately shut down. 
   
   Upon shut down I checked the rockers for any type of out of the ordinary condition. They were cold adjusted at rebuild. There was nothing evident. #4 sparkplug was normal.
   
   I did a compression check and #4 was only 110 lbs. The rest were as expected at about 190. While doing the comp check there was a sharp "clack" noise consistent with one cylinder making it. I'm assuming that something happened in #4. I'll do a pressure check tomorrow on #4 with a homemade modified spark plug and listen for escaping air noises.
   
   The rockers on # 4 were removed to eliminate any valve motion and the "clack was still there.
   
   Anybody have any thoughts on any other diagnostic trick to be used before I pull the left side off? I wont pull the whole drive train again. I don't have a bore scope to look into the cylinder.
   
   
   
   


MIKE KOVACS