Engine Rebuild

matthewing · #1 12-03-2015, 11:31 AM

I'm looking to do an engine rebuild in the near future and want to start buying parts. My biggest issue is finding usable engine internals. I'm still deciding whether I want to do a stock rebuild or beef it up for the future (while keeping it NA).

If I go the stock route I'll more than likely still have to get bigger pistons (forged or not) since I'm assuming the cylinders will need to be bored. So what would be some options? I'm trying to shy away from custom ones but if I have to I will.

As for beefing it up I'd want forged pistons, forged rods, upgraded rod bearings, upgraded main bearings. I've lightly read some threads on what others have used but want to be absolutely sure I'm ordering the right parts. So if anyone has information on what engine they're from or good sources that would be awesome!

Pistons: ?

Rods: Eagle?

Bearings: ACL?

Crash_Bandit · #2 12-03-2015, 09:14 PM

I don't know about all of the items on your list, but when I had an engine rebuilt, there had been damage to the cylinder walls putting me on the path of looking for new pistons.
The bad news, you're probably looking at custom made oversized pistons as no such beasts exist on the open market. I've seen comments from others on the forum mentioning where they went to get some made when they decided to do this.
In my case it ended up being easier to re-sleeve the cylinders than hunting down someone to make pistons. Luckily the pistons themselves were in perfect shape so nothing else needed to be replaced. The damage was caused by a head gasket leak that rusted the piston rings to the cylinder walls.
Good luck!

longassname · #3 12-04-2015, 06:12 AM

Are you looking to rebuild the engine yourself or do you have a local engine rebuilder in mind? Unfortunately, most people who try to take this job on themselves fail. I don't want to discourage you from trying but you should be aware that it is a bigger and more difficult project than one expects up front. If your main goal is to end up with a good engine then you should probably have a rebuilder do it. If your goal is to enjoy the project of doing it yourself then you should probably start a thread on the project so you can share your experience with those who also don't know and get help from those of us who do at the same time.

longassname · #4 12-04-2015, 06:14 AM

I don't have time right now to sufficiently explain the answers to any of your questions but I will come back later today and start answering your questions.

longassname · #5 12-04-2015, 09:02 AM

Ok here we go.....

First about rebuilding an engine to use stock pistons:

Honing and boring are two different things.

Honing is the process of refinishing the cylinder walls to create an ideal surface finish to break in a newly installed set of rings and then create a good seal. It removes a small amount of material. Equate to sanding with a abrasive if that works for you

Boring is the process of resizing a cylinder by cutting away larger amounts of metal with a cutting tool. Boring does not create the necessary finish. Boring is always followed by honing.

Subaru does make oversized pistons. You can go to the dealer today and order .25mm oversized pistons and .25mm oversized rings.
The part number for the left pistons is 12018aa520 $87.35 each you need 3
The part number for the right pistons is 12013aa520 $87.35 each you need 3
The part number for the rings is 12033aa460 $351.05 for the complete set
You will find the pistons are listed as piston sets. That means they include the pins and circlips not that you get more than 1. So a complete set of new pistons and rings will cost you $875.15 which is less than a custom piston set will set you back.

.25mm is basically 10 thousandths of an inch. This means your cylinders will have to be bored..so both bored and honed.

So the way it works out is buying new parts from the dealer is a little less expensive than going with custom pistons and you know ahead of time they will be right. Custom pistons aren't always right.

There is another option which can offer a little better performance for a little less money but it requires more access to used engine parts than most people have. Standard size Subaru pistons come in 3 fitments (A,B,C). A size pistons are the biggest. Your engine will have an assortment of these sizes in it. You can collect together a complete set of A size pistons and send them to Calico Coatings or Swain Coatings to get performance coatings. They will bake and then chemically clean the pistons so they are nice and perfectly clean and prepped before coating them. Then they can apply an anti-scuff/anti-friction coating on the sides and a thermal barrier coating on the tops. Your engine builder can then lightly hone your cylinders to perfectly fit the pistons. Here is just such a set I've collected together. If you want it I'll give it to you for $150. It includes an extra set of lightly used genuine Subaru rings you could use with no problem.

longassname · #6 12-04-2015, 09:22 AM

Now...Tools

Chances are your engine builder has never built an EG33 before. That means he will need to MAKE himself some tools to do the job. EG33s require some special tools and some of them are NLA...that's subaru code for no longer available. I'll show them to you now so you can assist him in figuring them out.

Ok, so Subaru engines are "pancake blocks." That means the block is two block halves which bolt together around the crankshaft. The rods install onto the crankshaft 1st. Then the block is assembled around the crankshaft. Then the pistons are pushed in through the top and the pins that attach the pistons to the rods are inserted through access holes in the front and rear of the block. Then the circlips which hold the pins in are inserted through the holes in the front and rear of the block. There are other 6 cylinder Subaru's out there now so the circlip pliers are probably available again but the piston pin installers and pullers are different.

Soo..... to disconnect the pistons from the pins so we can disassemble the engine we need circlip pliers and a piston pin puller. The piston pins do not usually come out easily.

The circlip pliers in the piston are a genuine Subaru tool but they are clearly made from a needle nose pliers. They have a notch cut into them to hold the circlip nicely and extra long skinny handles that let them fit through the access holes and go all the way to the center pistons.

The piston pin puller is a custom slide hammer I had to make myself.

longassname · #7 12-04-2015, 09:34 AM

To install pistons, in addition to the circlip pliers you need a good piston ring compressor and a piston pin installer. Luckily for us Summit sells a nice piston ring compressor for pistons in our size range. Piston pin installers just amount to a rod with an end that perfectly matches the ID of the piston pin so that it isn't wobbly and difficult to line the pins up with the holes but isn't tight so the pin doesn't get stuck on the tool. The ID of our piston pins is different from later model Subaru pins and from aftermarket piston pins. In my picture you will see the genuine Subaru Eg33 piston pin installer and one that I made being compared. The one I made fits both the stock EG33 pins and the high performance lighweight pins I used with my forged pistons.

longassname · #8 12-04-2015, 09:40 AM

These are the Subaru tools for working on the the heads. A valve spring compressor, guide installer, seal installer, etc. You don't need any of these. Take your heads to the guy who specializes in heads. He's got a special press set up to let him do all this stuff on any overhead cam head.

longassname · #9 12-04-2015, 09:47 AM

These are the crank and cam tools including seal installers. They are very nice to have and it's certainly easier to do a good job installing seals with the right installer but people figure out ways to get by without them. The silver spanner is for tensioning the scissors gears on the camshafts. If you read the service manual before taking your engine apart and put the bolts through the gears to hold them in their tensioned position then you won't need this tool. The gold spanner is the cam pulley tool so you can correctly torque your pulley bolts and aid in installing the timing belt. People figure out ways of getting by without it. The stuff on the right are the crank tools (actually there's another piece to the crank tool I forgot to pull out) and the seal installers. Again..people figure out ways to get by without.

matthewing · #10 12-04-2015, 10:13 AM

Hey LAN, I've read a ton of your posts. It's nice to finally talk with you! One of my good friends is constantly rebuilding different Subaru engines so we'll be working together. I have two engines. One had a possible bearing failure and the other is in the car. I had time last night so I checked out the bad motor and it will definitely need to be bored. I didn't look at the stamps on the pistons but I'd assume I wouldn't have enough to make a complete set of A pistons. Let me think on the offer though. I'll get back to you shortly. Do you happen to have the measurements of the different pistons? If not I'll get them later when I split the block so no worries. Do you happen to know how much coating pistons costs?

As it stands I'm hoping the engine I have in the car would only need to be honed so I can use the A stamped pistons.

matthewing · #11 12-04-2015, 01:14 PM

Hey thanks LAN. I didn't see your posts on the tools used for dis-assembly before I replied. I did a bunch of research a year ago on the needed tools and already made some. That slide hammer piston pin remover is NICE! Way better than mine lol

longassname · #12 12-04-2015, 02:02 PM

Well I can tell you your chances of success are much better if you start with an engine that doesn't have a bad bearing. An eg33 with a bad bearing is an eg33 with a bent crank. A bent crank means both the mains and pins will have to be ground. When they grind a crank they grind all the mains to one size. Unfortunately the holes for the main bearings in the block are not all the same size. Getting the crank right requires caging your new bearing set in the block(caging = assembling the block, torqued correctly, around the bearings after it is cleaned up but without the crank) and measuring each bearing bore then belt polishing each crank journal to match the corresponding bearing.

While we are on the subject EG33 cranks can not be left standing around the shop like most shops do with most cranks. This is not a big heavy cast crank. It will get bent if not pampered. It should be kept sitting in the bearings of one of the block halves.

longassname · #13 12-04-2015, 02:17 PM

It will be fine to be honed for coated A pistons but two engines will probably not provide enough A pistons to put together a whole set. Remember lefts and rights are different so you don't just need 6 A pistons. You need 3 left A pistons and 3 right A pistons. 4 or 5 engines is more likely to provide a complete set of A pistons.

matthewing · #14 12-05-2015, 09:16 AM

PM'd you about the A pistons.

longassname · #15 12-05-2015, 10:42 AM

cool, I was just looking at some of my stuff and I have a set of made in Japan standard size Clevite Aluminum rod bearings too if you want them.

I don't think I have any more main bearings but I'll look up the information on them now and post it here in a few minutes