Andrew's DiySB Rebuild

[M4rked1]

I really wish I had the time and budget to go as far as you on my rebuild. Looking great!

[StkmltS]

I fooled around with the heads this weekend and cleaned up the roughness inside the intake and exhaust pockets. I didn't remove much material, calling it "light polish" might even be an overstatement. It's addictive so I might go back in and clean it up a little more. Thinning the dividers seems like a good idea so I might give that a try. I've decided against porting or port-matching the heads. There's too much conflicting information out there and even if it's a good thing my stock motor won't benefit from it.

 

Tonight I'm going to finish measuring the rods and main bores, even though it seems futile at this point.

The main bores are acceptably in-line with each other, to the extent that my equipment can measure (straightedge and an 0.0001" shim).

 

I got my shorty DP and threaded bung back this morning!

The bung isn't welded on, but at least I've got it.

 

Backstory:

Coworker #1 was going to weld it for me, but he had a heart attack and died a couple weekends ago. Coworker #2 lives near coworker #1's house, and coworker #2 picked it up for me this weekend.

Edited July 18, 2016 by StkmltS

[StkmltS]

New oem sti pistons are on their way from Crawford Performance. They put forged pistons in enough new blocks that it's worth their while to sell the "take-out" pistons for only $25 each. New NPR rings are on their way from ebay, and JSC has kindly offered to trade me for some new King rod & main bearings. I want the bearings, they want my money. Win-win.

 

Everything should be here by Friday. Hopefully I won't need to play the mix-n-match game with the bearings and I'll be able to get the SB assembled on Saturday.

[StkmltS]

Valve heights are measured, and each new valve is numbered to match the valve it's replacing.

 

Each new intake valve is about 0.001" shorter than the corresponding valve being replaced.

All of the new exhaust valves are about 0.013" (thirteen thousandths) shorter than the old valves.

 

Hopefully the new-vs-old height differences are due to carbon build-up on the faces of the old valves that makes their overall lengths... longer. I really don't want to buy 8+ new buckets.

 

The GSC Power Division sticker provides that extra little edge you need when you're racing an Evo and your "stage 2" just isn't quite enough.

Edited July 20, 2016 by StkmltS

[birkhoff]

I wouldn't worry about o'all height just yet. The important measurement is from the contact point at the seat, to the stem tip.

 

Or, to put it another way, it is unlikely the face of the valve (which is one point in your measurement) will sit in the valve pocket to exactly the same depth as your old valves, even if you remove all the carbon on the latter. It depends on how the valves are ground, and where the contact takes place.

 

And they still have to be lapped in.

 

Does that make sense?

[StkmltS]

LH side head (on the right) decked a little less than 0.002" (difficult to measure) using 320 grit sandpaper and a verified[/i ]-flat piece of granite. I haven't re-inspected the head for flatness yet, but it was already acceptably flat so this is mostly just to give the head gaskets a fresh surface to cling to. And we all like to see pretty pics

 

I'm not worrying too much about the fire rings that are still very visible. Much of the original machining marks are also still lightly visible.

Edited July 20, 2016 by StkmltS

[StkmltS]

LH (on the left this time) and RH side heads after DIY decking. Slightly less than 0.002" removed from each.

I'm very pleased with how well they cleaned up, considering how little material I removed.

 

If your heads are warped I definitely don't recommend this method. From a quality perspective it would work, but it would take hours of careful sanding to get them flat. After an hour of back-and-forth, back-and-forth, back-and-forth... I imagine anyone doing it for that long would be prone to getting sloppy and making mistakes.

 

The RH side was a pain because of the hard coolant line that sits slightly higher than the head/block mating surface, limiting me to only a couple inches of movement on the sandpaper for "machining". That hard line is a real beeyotch and I can't get it to rotate even a little.

Edited July 20, 2016 by StkmltS

[StkmltS]

The extent of my "mild polishing" inside the heads. This is just from round #1, I haven't gone back in for seconds yet.

No valve seats were harmed during this exercise.

 

In a couple of the pics you can see a few little splotches of stray sanding marks in different places. Those aren't accidental, they're from me cleaning up random casting imperfections.

Edited July 20, 2016 by StkmltS

[xt2005bonbon]

I can't believe you're doing all of your measurements in imperial units and not metric .

[StkmltS]

(At work) when dealing with international customers we convert blueprints to imperial before even quoting jobs. It's also our common practice to require that customer POs acknowledge that our certs of conformance will be done in imperial vs metric.

 

This photo should explain everything.

[xt2005bonbon]

Beautiful picture

[birkhoff]

As with everything in Canada, we speak both languages and flip from one to the other without a thought. Want it in gallons? Imperial or US? Litres? whatever.

We don't even spell consistently! Centre, centred, centring, centering . . .

 

All that aside, 95% of my measuring tools are imperial so I really appreciate that Subaru USA has already done the conversions in the FSM.

[birkhoff]

Can you still feel those fire ring depressions? Earlier you said you thought they were maximum 0.002 deep. I'd be at least a teeny bit concerned about them -- there seems to be a special religion around getting the sealing surface right with Subaru.

 

Example. My heads were as clean or cleaner than yours when I took them in for decking. They measured dead flat. I asked the machinist to take off the minimum and the response was, I'd be surprised how much needed to come off to clean them up to spec. No marks of any kind left when they came back. I think I lost 5 thou thickness. Would have to check.

 

I'm no expert, particularly on the Subaru front. Could someone experienced with preparing Subaru heads chime in here?? Is it ok to leave those rings?

 

Is there is a similar issue with the case halves?

[StkmltS]

You can definitely still feel the impressions about 1/4 or 1/3 of the way around each combustion chamber.

Where you can feel it, it's probably a couple more thousandths below the surface.

Edited July 20, 2016 by StkmltS

[SBT]

FI engines find opportunities to leak. Don't give this engine that opportunity. Especially with the variability of the fire ring "placement" on each cylinder head v-a-v the previous HG. My engine, I'd make sure that deck was ready; plumb, square and true.

[StkmltS]

I talked to a few experienced car guys and read a few articles about decking heads, and it seems like the general consensus is that completely removing the fire rings is best, but not absolutely critical. If the rings aren't completely removed the new HG should still seal properly and fill in the gap.

 

However, as with other things I've almost-skimped on, I'm going to choose best over good-enough and put a little more time into the heads. I'll slap the the sandpaper back on the granite plate tonight and take a few more thousandths off the heads. Geesh...

 

So I was watching Launch Control this morning and I saw a brilliant idea. They were splitting a block in half and they had these little rubber/plastic/cloth/whatever sleeves over the rod ends to keep the rods from touching the cylinders. Genius! Maybe it's an ages-old idea but it was new to me and frankly, I'm a little more excited about it than I should be. Seems like old socks would work pretty well. Although lint would be a concern. Anywho, I just thought I'd share their cool idea with the Internet.

[Max Capacity]

How sad, I used those little rod bolt covers back in 1975 when I rebuilt my 340.

[birkhoff]

Rod bolts, yes, so you don't scratch the crankpins when you drop the piston/rod package down the bore. As MAX diplomatically points out, truly new ideas in this business are few and far between!

 

Rod socks, not so much. I made up a set of these thinking along the same lines as OP. Abandoned them after a few tries when they kept slipping off. Maybe they could have been modified, but I found the rods didn't mark up the bores anyway. Yes, they're gong to clunk around as you roll the block back and forth on final assembly. I just didn't find it worth the trouble and seemed a pretty good way to introduce contamination at the final assembly stage.

 

Fitting the mains you don't have the rods on anyway. That's where all the time goes in.

 

Question. You are going to continue sanding the heads. What about the block? Are there not similar issues on the fire deck?

 

There is always the option to pack up all 4 pieces, grab the pistons, and drop them at any decent machine shop. 1 day later, perhaps $150 poorer, you would have the heads and block decked and the bores cleaned up with a professional plateau hone.

 

A person would have to be a real ba$tard to suggest you didn't build it from scratch just because you used a machine shop that has the necessary (expensive) equipment to do that part of the job properly and efficiently.

 

Just saying. . . .

[heiche]

yeah, a couple short pieces of fuel line, or some other hose that fits snugly over the end of the rod bolts can sometimes be helpful

[StkmltS]

Rod bolts, yes, so you don't scratch the crankpins when you drop the piston/rod package down the bore. As MAX diplomatically points out, truly new ideas in this business are few and far between!

 

yeah, a couple short pieces of fuel line, or some other hose that fits snugly over the end of the rod bolts can sometimes be helpful

 

Unless I have things seriously out of order, the rods get attached to the crank, the case halves go back together, and the pistons/rings get dropped into the cylinders and then attached to the rods via the access holes in the sides of the block. Why would the rod bolts ever need covered?

 

Question. You are going to continue sanding the heads. What about the block? Are there not similar issues on the fire deck?

 

The block doesn't have the same impressions as the head. I don't have any good pics post-cleaning, but if I remember correctly they're almost perfect as-is. You've got me curious though, so I'll take another good look at them tonight. If they need sanded they'll get the same treatment as the heads. Sand a little > say I'm finished > sand again because once didn't get it all.

 

There is always the option to pack up all 4 pieces, grab the pistons, and drop them at any decent machine shop. 1 day later, perhaps $150 poorer, you would have the heads and block decked and the bores cleaned up with a professional plateau hone.

 

A person would have to be a real ba$tard to suggest you didn't build it from scratch just because you used a machine shop that has the necessary (expensive) equipment to do that part of the job properly and efficiently.

 

Just saying. . . .

That's an option, but overall I've spent a decent amount less than planned so far... and I've been thinking about using that "saved" money to convert my VF40 into a JMP-VF40

I didn't include the turbo in my original plan because of budget constraints, but it's looking like it may be possible while still keeping the project under $4k. Tuning for a non-stock turbo would be a big hurdle to overcome, and I'm not sure that I want to tackle that giant yet. Please be encouraged to convince me otherwise!

[heiche]

Unless I have things seriously out of order, the rods get attached to the crank, the case halves go back together, and the pistons/rings get dropped into the cylinders and then attached to the rods via the access holes in the sides of the block. Why would the rod bolts ever need covered?

 

Good point. Guess I'm remembering other "normal" engines I've worked on over the decades. It all sort of blends together

[Tehnation]

wouldn't it make more sense to attach the piston to the rod, and then drop the entire thing in? you basically take out an entire step, or am i missing something? Edited July 21, 2016 by Tehnation

[StkmltS]

Once the halves are together I don't think you can get a torque wrench, or any wrench, in there far enough to put the caps on the rods. When I get to that point (maybe this weekend if my std size bearings work) I'll take good pics that should explain it clearly.

 

Sent from inner space.

[Tehnation]

this engine is so stupid......

[StkmltS]

How about these apples?

The fire rings are gone, and so are the muscles in my arms. It took about 2 hours of solid sanding; definitely not an enjoyable experience. Highly recommended for the cost-savings though.

 

Tonight I was talking with my wife about maybe rebuilding the turbo and she said "just do it, I don't want it ever blowing up". She's not enjoying this rebuild nearly as much as I am. Maybe that's because there's an engine sitting in the shower and now we have a delightfully fine aluminum dust coating the dining room table.

 

Sent from inner space.

Edited August 2, 2016 by StkmltS
pic uploaded to server