Building My S52 bottom end. Help me not mess it up! (56k NOO)

[shiboujin]

Cross post from my bimmer forum threads. Hopefully you guys can help me out :)


I'm a complete engine building newb so be gentle. I want to make sure I'm not going to destroy my engine before I even get it in the car. So anyone who has done this before and knows what they are talking about feel free to chime in. I'm trying to work so that I'm 100% sure before I finalize things.

Lets start with piston rings. I started by pushing in the 2 combustion rings and measuring what they currently are. First one is 0.018



Second one is 0.012.


Side question, It's started to surface rust from the place I accidentally touched it and didn't know. What should I do about it?


Wiseco said the top side of the rings are marked. I see an N on both rings on what I guess is the top side. But which one is the top ring and which one is the second? One is darker and the other is lighter. The darker one has a taper on the OUTER edge (pictures show inner).



Also, I'm guessing the dot points towards the front of the engine right?


Here's the oil rings. I think they are in as wiseco specs. Bottom oil ring is 90 off from the top one. You can see the bottom one in the pic and part of the top gap in the top. Wiseco says the oil rings to not need to be gapped.


Of course the part where the squiggle/center oil ring gaps is in the flash. But like wiseco specs, they do not overlap, they just kiss. So far so good right?


Ok so wiseco says 0.0050" for top ring for top ring. 0.0055 for the bottom on a basic street turbo car. 3.425 (bore on the wiseco box) X the previously mentioned numbers give me 0.017125 and 0.188375. So I'm guessing the 0.018 gapped ring I mentioned earlier should be 0.019? And the one that's already 0.012 should be gapped to 0.017? I don't have a gapper wheel but will a metal file work? Just do a few at a time on one side and debur when done right?



Machine shop gave me 5 oil squirters back after the align hone job. I pulled a 6th from a spare block. They just set in right?


Again some surface rust on that surface from where I carried the block. I oiled it and rubbed it. There's a dark rusty spot inside though. Should I be concerned?


I got some Lucas assembly lube and lubed up all the crank bearing surfaces prior to the bearings going in. I figured "lube EVERYTHING". Right?


Thrust main bearing goes on the second from the rear bearing right? Again I lubed the crap out of it.



Wasn't sure how these aligned at first but it turns out you can't put the main caps on backwards (whew). Also, yay ARP main studs!


All set in for a second.


I set the crank in and put on a few main nuts but not super tight. probably 10ft/lb. Enough to seat the bearings together. The crank rotates freely (yay?). This crank was out of this engine. Should I brake clean it off then lube it and shove it on during final assembly? Or just towel it off and lube it? I'm also planning on taking off the trigger wheel since I won't be needing it.




If you can answer any of these questions or at least confirm I'm not messing it up, lmk! Thanks!

[LJ851]

how are you ensuring the rings are square in the bore before you measure them? Oil rings should be 180 apart. I like over the pin bore. Oil ring expander in between the two, i like intake side. N is up. first and second ring should be visibly different if not different sizes. I would take some fine steel wool and solvent to gently remove rust. oil all machined surfaces until you are ready to build, then clean everything, then build.

[shiboujin]

I put the oil rings on the piston and set the piston into the bore upside down until it stops. So it's def square. Ok so I think I know which rings are top and bottom then. N is def up?

Steel wool. Good idea. I'm probably going to disassemble everything, clean, relube, reassemble.

[lolcantturn]

I am going to be monitoring this thread for the duration of this assignment.

[e46s54dr]

Off topic but why didnt you get the block resurfaced while it was at the machine shop? Is there any particular reason that I should know about while Im rebuilding my s50?

[EduardoGomez]

I can tell you that machine shop did a poor job on bore honing.

They used too much speed and not enough up and down bore hone movement. This resulted in flat cross-hatch pattern and that engine may consume oil.

In order for the oil rings to properly crape oil from the cylinder walls they need to ride on a 40 degree cross-hatch pattern, like the one that you can see in this photo:

[LJ851]

Top ring is usually smaller and shinier (harder) Second ring a little bigger and duller (softer) You want to make sure you have the complete difference in ring gaps between top and second rings , even if you have to make one a little over spec. This ensures the rings wont flutter. I also agree with Eduardo, the hone job is not proper. Why didnt you get the block decked while it was at the machine shop? I would want a fresh, flat surface especially w/boost.

[shiboujin]

I am going to be monitoring this thread for the duration of this assignment.

Go for it. shouldn't be long though. I'm just building the bottom end. The top is mostly already done and the rest will be done in car since the engine is currently in my basement (flight of stairs >_<).

Off topic but why didnt you get the block resurfaced while it was at the machine shop? Is there any particular reason that I should know about while Im rebuilding my s50?

Iron blocks don't normally warp. I could have but it didn't really seem worth it to me. A tiiiny bit more compression would result when I'm sure this will work fine. I'm using a stock HG instead of an MLS.

I can tell you that machine shop did a poor job on bore honing.

They used too much speed and not enough up and down bore hone movement. This resulted in flat cross-hatch pattern and that engine may consume oil.

In order for the oil rings to properly crape oil from the cylinder walls they need to ride on a 40 degree cross-hatch pattern, like the one that you can see in this photo:

I think the pictures are an optical illusion from what I posted. Regardless, I have personally seen an S52 running 9.5s in the quarter mile that goes to this particular shop for all his machining needs. This isn't some crap shop.

anywho, anyone have answers to my questions?

[shiboujin]

Top ring is usually smaller and shinier (harder) Second ring a little bigger and duller (softer) You want to make sure you have the complete difference in ring gaps between top and second rings , even if you have to make one a little over spec. This ensures the rings wont flutter. I also agree with Eduardo, the hone job is not proper. Why didnt you get the block decked while it was at the machine shop? I would want a fresh, flat surface especially w/boost.

Yea that's what I thought. Cool thanks man.

[flyboyx]

the way you have your thread worded is really confusing, but the feeler gauges you posted show a ring gap of .018 and .012 which doesn't seem unreasonable. however the photo of the pink page shows a tolerance range of .0045 and .0055. if we are talking about the same thing, your rings would way the heck out of tolerance. however, that would seem a really tight dimension for a ring end gap. the 0045/0055 is likely the gap dimension between the ring and the piston groove. anyway, it is pretty hard to tell by the information provided.

i am not trying to discourage you in any way. this type of project is so much fun and a great learning experience. however, we caution you that if assembled incorrectly, you just wasted one hell of a lot of money. i don't really have a lot of confidence by the discourse of your text that you are heading in the right direction. it might be worth your while to pay the machine shop a couple hundred bucks to do the job right the first time. perhaps you know someone with lots of engine building experience who can do this for you while you assist and learn to do it properly. just ask luis about his adventures in engine rebuilding. there are a lot of good lessons in his threads. however you choose, i wish you good luck. if you have any specific questions, you can pm me and i will answer them for you to the best of my ability.

while you have the engine apart, take it back to the machine shop and get the deck milled for gods sake! make sure to get the mating surface of the head milled as well. how do you know if the engine was overheated at some point during its lifetime? even if it hasn't, it could still be very easily off by .003. that is easily enough to give you problems down the road. penny wise and pound foolish. i don't understand...you spent all that money on the arp main bolts and the rebuild kit. do it right the first time, man.

[shiboujin]

Sorry I should have clarified. I've been following the wiseco instructions to the T on the pistons. They have a mathematical formula based on your car's purpose and bore. My bore (indicated on the cardboard lid of the wiseco box) says 3.425. Wiseco says you multiply that by the spec for each ring to get your desired gap. So it's 3.425 x 0.0050 for the top ring and 3.425 x 0.0055 for the second ring.

The gauges I posted are what the gaps were out of the box. I have not started grinding as I wanted to double check with people that knew so I don't mess anything up.

I will admit that I am nervous about this. But I have helped put together a few other engines and have friends on the phone that have done many engines. I would like someone to do it with me but I don't have anyone local. I could pay a shop to do it but what's the fun in that?

I'm nervous but fairly confident I can do this. The bottom end seems pretty simple at this point. The rings seem fine as long as you get them gapped right and have no burrs. Everything else I have done before.

[LJ851]

You will need a very fresh file to gap the rings. Only file on one side of the ring. After you file push the ends of the ring together and you will be able to tell if you filed square. go slow, you cant put metal back! I believe you that the picture of your honing could photograph different than it looks in person.

[LJ851]

Whats happening with this build?

[e30s50dan]

Use assembly lube like redline,etc for bearings

[shiboujin]

Whats happening with this build?

Broke a piston ring but the rest are in and gapped properly. the file worked out great. Gonna plastigage the bottom soon and then finally assemble. The rest I've done before so thats no biggie.