Pistons 9 grams lighter replacement
 

At the beginning of the season I freshened my IA2 block with new pistons. I weighed one of the old pistons and made the new ones match. I had a problem last year at the end of the season. I have ordered 4 new pistons to replace the damaged ones. I used the job # from the existing pistons that I ordered for it last year. I got them and they are 9 grams lighter for some reason. I decided to weigh the pins to see if I could find some that were a little heavier. As I weighed them I had 6 that weighed 153 grams and 2 that weigh 144 grams. Then I remembered I had 4 pistons that were .005 bigger than the other 4. I assume that’s why I had some lighter pins although I only have 2 that are lighter. This whole time I’ve had 2 pistons assemblies that are roughly 9 grams light. Now with the new pistons I can use the heavier pins to make them match the old pistons with the lighter pins. Problem is I only have 2 light pins. Is it worth getting 2 more light pins so all the pistons assemblies match? Or is 9 grams on 2 of them not worth worrying about? It’s been running for about 6 years with 2 of them weighing different and I haven’t noticed any problems.

I always make all pistons weigh the same and pins all weigh same my machinist gets the the weight difference within 10ths of a gram

How did your rod bearings look on those piston and pin combo's, do you still have them to look at?

i could deal with being 4 grams off, but 9 would be a cause for concern to me!

They all still look new. I only put about 120 passes on them this last time around.
The last time I had it apart I had reused the rod bearing 3 times because they looked so good. It got bored and new pistons this last time so it got all new bearings. The old ones still looked good enough to reuse. I decided to get a couple more lighter pins and call it good. The piston assemblies will all weigh the same now.

It ran fine with that jet extension u found in one of the holes, it just made a little noise. If this new deal isn't making any noise, let er rip buddy. :D

Brian

Haha!!! True!😜