As most people know, just before Techenders Sptember 2018 when I was wondering what major repair I would need to be doing just to get to Techenders, my home built 1641 dropped a valve and managed to hole the crank case. So I was allowed to buy a Preservation Parts 1641 from Just Kampers. It is described as being all new apart from crank and con rods. It features AA pistons and cylinders and an Autolinea case and heads. This arrived very quickly, ordered Friday it came next Tuesday, it took me a couple of weeks to collect parts needed, and a day to strip down the old engine tinware etc, and a day to install the new engine. The engine is delivered post break-in but empty of oil, needing running in. It carries a 120 degrees C temperature recording sticker on the top of the case: exceeding this voids the warranty. The main difference is the case is thicker in places than the originals so tinware needs some snipping with tinsnips where case corners have rounder fillets of case material in them, basically round the crank pulley area. Also the dipstick tube is aluminium not steel with thicker walls and the stock dipstick locked in and then pulled the whole tube out when I first tried to check the oil level. A quick splash of carb cleaner then high temperature epoxy stopped it moving again. I noted some pitting on the end of the crank where the pulley fits. Also there has been an oil seep from the underside of the engine, it looks like the nuts are leaking on the oil strainer plate. On first oil change at 500 miles there was a small amount of RTV and one small swarf spiral caught on the strainer. Much less glittering metal than my previous engine which never really stopped having metal in the oil. I will buy it some Dowty washers to see if they do better than the stock style copper washers. Oil pressure at hot idle is 20+ psi, at 4300 rpm it maxes out around 46 psi. The engine runs cooler than the previous engine: with an oil cooler I see 100 degrees max rather 115 with the old engine. Cylinder head fins were well cleaned up by the builder and these too seem to show a drop in CHT at the same place as the old Autolinea heads I used before. In general driving, low end torque is improved, I can accelerate from 25mph on 4th and it climbs hills about 10mph faster than my previous engine. But it really does not want to go much faster than 70mph/4300 rpm, the old engine would have less torque to reach 70mph but could run faster , I recorded 5700rpm in second gear when I forgot to change up on the old engine. It starts easily as expected and now it has run in I need to slow down the fast idle on the choke mechanism. Added: I am running this with a progressive carburettor jetted for the old 1641 engine but re bushed to stabilise idle speed as it had an air leak on the throttle spindle. That carburettor has a stock oil bath cleaner with preheated air feed. The exhaust is a JK stainless single quiet pack.