The last time I had my heads of I noticed the my "reputable" engine builder installed my pistons backwards i.e. the arrow w/ FRONT engraved on the top of the piston is pointing towards the rear of the motor. I have talked to a couple of guys in that are into chevys and they have said that some builders put pistons in backwards for more hosrepower. I do not know if this is true because I am not a builder. My gut says that it is wrong but I don't know if it is something to freak out about.
Just pull the engine and flip the whole thing 180*, that way your pistons will be right.
Installing "off set" pistons 180* from design will act like a longer rod has been installed. Cold start will have MORE noise, but it is usually woth 15-30 HP on a NA V8. It CAN make a marketable difference, at the cost of piston noise when cold. Leave it alone. On the next rebuild, check the skirts carefully for cracks, though. Some people (V8 guys) have reported cracks on the piston skirts from installing pistons backwards. BUT........there was probably other issues and not just eh orientation of the piston.
I would also check the big end of the rod (with the pan off) to make SURE they didn't just swap the whole rod/piston combo. That would create a serious pin loading issue. If the rod offset is in the wrong direction, it would also create a bad side load on the piston skirt. If it was built by a shop, call them and ask them if that was intended, or was there a mistake made?
Keep in mind this GN is not a daily driver. Here is the long story. In 1999 I had the motor out and rebuilt by a shop that assured me that they had done quite a few turbo motors and I let them do the motor. At the time I had a stock cam and bottom end. I told them, all I wanted was the closest thing to stock as possible. What I got in return was a block .30 over and a 218/218 cam. The only good thing they did do was talk me into nitriting the crank. I finally got the motor in and due to lack of preperation I broke the crank sensor and was unable to get the car to start and I had no idea what I had done. I took it to a buick dealer and they got the crank sensor fixed and let the fresh motor run for over a half an hour unwatched knowing that it was a new motor. I came to pick it up and it would not start, back into the shop. The cam sensor was not tightened and it had jumped and sheared 3 teeth off. At that point buick says we did nothing wrong and we won't work on it anymore. So back to the engine builder and they show me how the cam sensor had bounced enough to flair the oil pump shaft enough that it would not come out of the timing cover. The engine builder fixed the cam sensor and got it running. I came by to pick it up and there was a ticking. After some argueing they agreed to pull it in and pull the filter and see if they found anything. Metal in the filter and bearings are thrashed. Bottom end out again. New bearings and clean the crank, back together. I had a bad IAC that was replaced then the car sat because I was mentally tired and it was not as strong as before. I started to drive it again and was never on it with any real boost and it started to smoke. At that time
I was doing general repairs at an auto shop and we pulled the heads after a compression test, two wrist pins floated out and dug into the walls. Motor out and sleever installed in two cylinders. At that point I called the motor shop back and was furious 1) wrist pins floated out and damaged the cylinders and 2)the pistons are in backwards. The machine shop that repaired the blocked and fixed the wrist pins had to replace two connecting rods. Due to the offset and being in backward the crank removed material off of the rods. Motor back in and pistons were put back the way they were found. I did not know at the time. So to keep a long story from getting longer. I need to and my wife needs me to get this car working again before she makes me and the car go away. I want to make sure that if I pull it out for a cruise that it won't strand us. The motor will come out and be rebuilt but still trying to save up the cash.
Might just want to start over with a fresh short block, even a used stock one. Sleeving a block is alot of money, and if done wrong, it'll damage more things. The pins backing out is just plain POOR workmanship. PERIOD! Do NOT use the same shop to even have your plugs changed. Find someone local to you that races a Turbo Buick, and use who they use. Sorry to hear about your troubles.
I'm not far from you I have a few 109 blocks and a 109 short block w/ forged pistons and STD/STD crank.
And there is a very good machine shop in Augusta GA (K&P) who really does Turbo Buick engines.
I'm also good wrench on these things w/ all the tools.
I am embarrased to even ask this but here goes.
Find someone local to you that races a Turbo Buick, and use who they use. Sorry to hear about your troubles.
