[buster73]

Wanted to give an up-date on the status of my rebuild project. After a long winter break had finally time to complete the break-in phase having completed 1,500 km on the new engine last year already. Drained oil which looked like fresh from the refinery. Re-torqued head bolts with only two bolts moving slightly at 32 Nm. Adjusted valve gap and again very little adjustment needed. After installing the new oil filter and filling up oil, started the engine and immediately realized something was wrong. Engine ran on 4 cylinders only with cylinder 4 and 5 both dead. Spark was strong but obvious no fuel at idle and no combustion. Cleaned all jets without effect. Following Paul Abbotts trouble-shooting guide I suspected a hidden gallery problem, although somewhat unlikely that 2 galleries get blocked at the same time. Anyway took out the carb and drilled hidden gallery plugs as documented by Paul. Gallery of cyl. 4 actually showed some debris but for cyl. 5 nothing suspicious was detectable. After plugging the galleries with cal .177 lead pellets, installed carb again and found #4 now working but #5 still dead. Even fuel supply was there, cylinder obviously was too lean to fire. Only explanation was a vacuum leak. Spraying brake cleaner around the inlet manifold confirmed a leak between inlet manifold and head. After taking off carb and manifold, gaskets seemed to be all fine. Looks like gaskets and the sandwiched phenolic spacer had settled slightly, opening up a small gap between heads and manifold. For next re-build I will add "re-torquing manifold bolts" to my check-list ! Glad to report engine is running great again and with the break-in completed the fun can start. Next step will be fine tuning of the carb jetting.