SNS Engine Rebuild
My intermediate level balance spec puts all the pistons with matched pins within .5 gr of each other for the full set. My race epic is .2gr.
That said, yours are definitely close enough of you are only balancing the reciprocating mass, and not dynamically balancing the remainder of the rotating mass. The rotating mass is light years of imbalance compared to what the pistons will be.
That said, yours are definitely close enough of you are only balancing the reciprocating mass, and not dynamically balancing the remainder of the rotating mass. The rotating mass is light years of imbalance compared to what the pistons will be.
Looks like the remnants of broaching the hexagon.
Material removed to create it from a round hole is not turned into swarfe but pushed to the bottom where it stays and that's perhaps what you see.
https://m.youtube.com/watch?v=pH3jWBnBmZo
Thank you hardtailer - Very interesting and makes sense - Appreciate the input
I was able to begin assembly this past weekend and made it through stage 1.5 getting the crank carrier assembled and three connecting rods onto the crank. The video series is excellent to have as a guide allowing me to move from step to step very quickly. Couple points on my assembly:
1. Inserting the piston squirters, I found the first one started in very tight. I pulled it out and added a little lube and then they all seated well. I almost forgot to install them as I prepped the bearings.
2. The connecting rod for #4 initially felt tight on the journal. I used K1 connecting rods and they have a two-stage torque. After the initial 25 ft-lb torque I checked how it felt on the crank and it was "sticky". Not like the rods on 5 and 6. I removed the rod, re-lubed both journal and bearing and switched the placement of the bolts on the rod. I re-torqued to 25 ft-lb and the rod felt just like the other two. I then torqued another 55 degrees as recommended by the manufacturer and all rods operate smoothly.
3. Crank end play was 3.8 thousandths ... slightly tight ...
Other than these items, the assembly was pleasantly uneventful. Now I just want to get back at it but I'll have to wait until the weekend.
For this stage I have a crank that I got from LN Engineering as mine was ruined, the carrier is from my donor engine. ARP carrier bolts, genuine Porsche crank, and rod bearings, and K1 connecting rods that came with ARP bolts. I replaced the stock rods because they were pretty heavily scored. The carrier bolts had a three-stage torque sequence. Below are some pics for your enjoyment - apologies for the flipped images...still learning on this platform.
1. Inserting the piston squirters, I found the first one started in very tight. I pulled it out and added a little lube and then they all seated well. I almost forgot to install them as I prepped the bearings.
2. The connecting rod for #4 initially felt tight on the journal. I used K1 connecting rods and they have a two-stage torque. After the initial 25 ft-lb torque I checked how it felt on the crank and it was "sticky". Not like the rods on 5 and 6. I removed the rod, re-lubed both journal and bearing and switched the placement of the bolts on the rod. I re-torqued to 25 ft-lb and the rod felt just like the other two. I then torqued another 55 degrees as recommended by the manufacturer and all rods operate smoothly.
3. Crank end play was 3.8 thousandths ... slightly tight ...
Other than these items, the assembly was pleasantly uneventful. Now I just want to get back at it but I'll have to wait until the weekend.
For this stage I have a crank that I got from LN Engineering as mine was ruined, the carrier is from my donor engine. ARP carrier bolts, genuine Porsche crank, and rod bearings, and K1 connecting rods that came with ARP bolts. I replaced the stock rods because they were pretty heavily scored. The carrier bolts had a three-stage torque sequence. Below are some pics for your enjoyment - apologies for the flipped images...still learning on this platform.
Thank you Skip - I was impressed with the finish on these K1's from LN
Clean, clean, clean, and then clean some more - forgot to take a pic of the small mountain of wipes!
Thank you and you are welcome - trying to emulate (copy?) a few on this forum who do an excellent job with their cameras..working on orientation!
It really is...there was a certain enjoyment in the procurement process but this is better than legos and I'll get to throttle on it when I'm done!
Clean, clean, clean, and then clean some more - forgot to take a pic of the small mountain of wipes!
It really is...there was a certain enjoyment in the procurement process but this is better than legos and I'll get to throttle on it when I'm done!
I can tell by the carb cleaner, Kimwipes, and etc that you are paying attention to the video!
The reduced end play is faux, the grease on the shims is tightening it up a couple thousandths. Always does.
The reduced end play is faux, the grease on the shims is tightening it up a couple thousandths. Always does.
I decided to order a new snap ring and washer for the IMS tensioner paddle. Figured for the cost of those little pieces I could rest easy that I hadn't overstressed the snap rind during disassembly. Due to arrive in a couple of days and then I'll get back to it.
I was able to wrap up stage two when the washer and snap ring for the IMS tensioner paddle arrived. As I had a couple of days to wait on the delivery of those parts I skipped ahead in the assembly and tackled the first part of stage 6, assembling bank one pistons to their corresponding rods. I started early on a Saturday and the temps overnight had gotten to 65 in the work area. I had to heat up the pistons so that they would accept the wrist pins...I held them in my hands initially and then brought in the big guns (portable heater). My circlip install tools are brand new and the fit is VERY snug in the side of the piston. I pounded the tool (as gently as I could but enough to move the tool) into the counterbore of the piston to eliminate any gap between the tool and the land of the piston. I was able to seat all the clips into their correct position in the circlip groove. Indexing these pistons and rods for the installation in the engine is slightly different than stock parts; the pistons do not have any arrows on them for orientation but the JE literature noted that the JE stamped on the underside of the piston is to be set beneath the exhaust valves. For the rods, I set the bearing tang facing down. These pistons have counterbores for the circlip installation tool on both sides of the piston. Pistons 1-3 are ready for rings. Once the snap ring and washer arrived I went back to the crank and completed the install of the tensioner paddle and chains. With the crank ready to be dropped into the case I prepped the case by cleaning the cylinders one more time, installing a couple of gaskets, and confirming the pins that locate the crank in the case half were properly installed. I had my business partner help me set the crank into the case half and that went very smoothly. I bolted the aft end of the crank to the case half and then made my own Porsche Special Tool 9613 for the front end and used a couple of old head bolts to secure the crank to the case. Now the case is flipped with bank 1 point up, getting ready to receive pistons 1-3 after I confirm the ring gaps.
I am doing a similar build the only difference with the pistons and rods is that I opted for the Carrillo rods. Seeing your K1 rods makes me think I could have gone K1. They look great.
Keep up the good work.
Keep up the good work.




