Well the city made me scrap the parts car I had in the driveway, because it "was in a state of major disrepair." Whatever, I pretty much got done the research I wanted to do, aside from a test drive. But now I have a spare engine sitting in the garage, and it's so tempting to tear into it. I plan on taking the heads off and porting them, but I'm on the fence about if I should freshen up the spare engine with rings and bearings plus throw a cam at it while its on the stand, or if I should slap those ported heads on the engine already in my car. The difference in mileage between the two engines is roughly 80K miles. The questions I had were:
1. Is there a recommendation on ring gap for a turbo 3800? I used a formula of .006 multiplier x 3.8 inch bore off of wiseco's website for a top ring gap of .0228
2. I'm gonna leave the cam bearings alone, but should I replace the main and rod bearings? The spare engine has about 160K miles on it.
3. I'm kind of paranoid about reusing stock parts with this much mileage on 'em. Specifically having a rocker bearing fail, or dropping a reused valve do to fatigue. Are there any reports of such things happening?
4. Is it possible to install/remove heads in the engine bay with head studs?
5. Is checking valve spring install height an important thing to do? Intense Racing seems to make a big deal out of it as it's mentioned on every valve spring page. I plan on using the Manley 150# springs that they sell, and on that page it says that no head machining is required.

 

No idea what the aftermarket piston big turbo 3800 builds are running for ring gap. The one thing to note is the old saying "too much gap and only you will know", "too little gap and everyone is going to know" (because it'll frag a piston and could turn into a complete catastrophic failure depending how bad it frags). Its better to have a little more blow by than ideal than to have a broken boat anchor.

This is just 2 engines for 1 car now, right? IMO I'd take the better condition engine and leave the bottom end 100% stock. No rings / bearings / anything below the heads and make that your backup (or perhaps your starter setup until you get the other engine finished) 2 reasons:
-The SBE engine will likely be your reliable go to if something goes wrong in the engine you're tinkering with. You'd hate to have your built engine grenade only to drop this in and have it grenade also as that defeats the whole purpose of a spare. The chances of it being unreliable due to mileage is far lower than the chances of it being unreliable if you start screwing with it too.
-The SBE 3800 will handle all you can throw at it for now anyways as long as it has good fueling and no knock. Theres no real benefit to spending any extra time / money on it if the ultimate goal is to to make the other engine a max effort build.

IMO if you're really that concerned about the mileage, then go grab a ~100k or less stock bottom end. They're harder to find these days, but certainly not impossible.

I've never heard of a stock 3800 rocker break or a valve break that wasn't the result of something else (usually an aftermarket spring or retainer). Not saying its not possible, but there are plenty of 200k+ 3800s out there to attest to the longevity. The stock cam is really fairly small in terms of cam size so its not particularly stressful on the valvetrain. The stock engines also don't really shift all that high either.

The hard part about getting too worried about it is its going to cost a lot of time and money to go through and replace every possible wear component on your 'stock' / spare engine. That effort is much better spent getting this thing on the road with the turbo.

Heads are no problem with studs. If it wont clear, just pull the studs as needed. They're not going to be much more than finger tight anyways.

Cant be of any help on this one, I bought my heads assembled from zzp with the 150s installed.

 

I do have two engines for just the one car now. The reason I want to tear into the lower mileage engine I pulled out of the parts car and refresh it, instead of putting it in the car and building the higher mileage engine, is because while it was sitting it got water in the oil, and possibly in the heads. Plus, I really don't know its history, how well it runs, etc. I do know at least the recent history of the high mileage engine, and that it runs great. I'd rather tear the lower mileage engine apart, give it a thorough once over, hone the cylinders, etc. If you really think the stock bearings and rings can be reused, assuming they look good, and that the rockers and valves will hold lets say 500-600hp for now, I'll save the money then.

The reason I'm not out hunting for the lowest mileage engine I could find is time and money. I want to spend as little as I can right now. I know that might sound a bit counterintuitive, given the 1400$ ECU and thinking about refreshing an engine. Life has thrown me a bit of a curve ball, and now I'm trying to save as much money as I can. But I still want to indulge in my favorite hobby a bit.

 

Yuck, water in the oil could be bad. I get the hesitation there now.

Id probably just flip flop my suggestion then- don't touch the bottom end on the high mileage one and just use the low mileage one for your big rebuild. Any way you go, I'd really think hard about leaving one bottom end totally stock and untouched for reliability reasons. Tearing into the bottom end of 3800s often ends up in blown engines.

I've actually done something similar to what Im suggesting. The engine in my monte is a full rebuild, fresh everything, forged pistons, etc. But ive also got a ~75k mile L67 spare untouched bottom end complete except for the oil pan that I keep off to the side in the garage in a sealed, oiled bag. I knew the previous owner and while it was raced a bit, it wasnt heavily modded and was well maintained. Luckily I've not had to use it yet.

 

That's exactly what I had in mind, building the spare engine, and leaving the current one untouched. I'm just concerned about the condition of the bearings and rings. I don't have the money, nor the need really at the moment, to do a full rod/piston bottom end.

 

Another couple questions:

1. Is there such a thing as too much wear on the top of the valve stem? Mine aren't mushroomed, they're just worn by the rockers.
2. Why are the coolant passage holes in the head gaskets so small? Compared to the actual size of the coolant passage in the head and block, the head gasket isn't even 1/2 the size in some places.