So, I'm thinking about putting a cam in along with my turbo setup, but I have a question. The specific cam I'm looking at is ZZP's ST4 cam. The engine has 230k miles on it, so is it necessary that I replace the cam bearings while I have the engine and cam out? I've never done it, but I'm comfortable with learning. I'm planning on freshening up the oil pump while I'm in there, so oil pressure isn't my concern. I would be replacing the entire valvetrain except for the valves themselves, and to get the most out of the turbo and cam, I'd be porting the heads while I have the engine out. Then putting it back together with MLS head gaskets and head studs. As much as I really want that lopey idle, I'm just a bit on the fence about going for a cam.

 

Thats a good choice IMO for a nice street/ strip setup. Has been proven to be 600+ whp capable but is still very tame for a street car. You're certainly leaving some power on the table vs a max effort drag cam, but if you plan to spend more time on the street than the strip, then this is a great balance.

TBH I've never seen a 3800 spin a stock cam bearing. There isn't a ton of stress on a stock cam and it spins half engine speed. Vast majority of the time, I'd never recommend touching them.

With that said, that's a TON of miles, probably in the top .1% of mileage for 3800 cam swaps. For $20 its worth the peace of mind to do it. If you're pulling the engine to refresh everything else anyways, it wouldn't make sense to risk leaving the stock ones in there. You'd really hate to risk a brand new cam and more for $20.

If you're worried about install at all, whichever machine shop is doing your bottom end machining will probably do it for next to nothing. I ended up letting the shop put mine in because it was less than even the cheapest tool online.

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Then putting it back together with MLS head gaskets

Keep in mind these gaskets are picky about surface finish. Make sure when they deck your block and heads that they put a fine enough finish on there. I don't recall if the gasket OEM or the 3800 aftermarket vendors specified a RA value, but one of them provided a minimum surface finsih value to ensure good sealing as people used to really struggle with these and even started playing with copper spray and such to get them to seal up right.

I honestly didn't have good luck as mine leaked. My heads were surface ground ultra smooth and my block deck was machined well within the specified RA. Mine looked to have been leaking between the layers. I know they've probably long since resolved the issue, but I'd probably at least consider drilling out the rivets that hold the stack together to do a thorough wipe down of each layer before assembly. I know some people back in the day found some notable debris stuck between layers. No idea if that was my issue or not, but I was not thrilled to have to replace basically brand new head gaskets - especially since they started leaking back when I still had a M90. As a result I've switched to a stock style gasket and knock on wood its been fine ever since.

Not trying to scare you away. No doubt they work super well on the LS platform and certainly many have run them on the 3800, they're just far more temperamental than regular gaskets here.

Unfortunately in general turbo cams are the least lopey of the bunch if the sound is what you're after. While the ST4 is lopey enough to be noticeable that it's not stock, its a really mild lope IMO. Just don't want you to think it's going to be some kind of hard core v8 NA drag car lope (or even big cam 3800 NA / SC) as its nowhere near that unless its not tuned or you've got the idle cranked silly low.

The second part of that statement is really puzzling to me, especially given all your other threads. You're thinking about 8k rpm, hand porting every single part regardless how tiny of an impact it has, and hand making all kinds of one off parts for the turbo setup, but you're not sure about a cam?

Just seems a bit crazy to me to spend all kinds of time worry about fractional horsepower gains and shooting for the moon on the build, but to even remotely consider leaving all that power on the table with a stock cam. IMO the real question should be shelf stock cam or one off custom grind.

 

Speaking of bottom end machining, what is recommended for going turbocharged on this high mileage of an engine? Just a hone if there's nothing wrong, new rings, and bearings all the way around?

Is there a sealing benefit on this engine big enough to warrant going for the MLS gaskets, or would stock gaskets with head studs do the trick?


I'm not on the fence about whether I should put a cam in the car in general, it is definitely going to need one. I'm just on the fence about putting it in at the same time as the turbo setup. It's a lot more of an expense and time to get all the camshaft related parts, as opposed to the turbo kit which I basically just have to get around to finishing the headers, then installing.

 

The hard part is that there is no standard recommendation because you're way off the beaten path for 3800s.

1. Very few people rebuild them at all. There are tons in junkyards with various mileage on them for cheap. Very few people rebuild in general for strength issues as very few have make enough power to break stock stuff. Also the history of rebuilt 3800s is pretty poor. Lots of stories of freshly rebuilt 3800s not making it 10k miles.

2. I can't think of anyone starting a build at 200k+. Even just using 200k+ parts. Its probably been done, but its just super rare as there are tons of 3800s in the junkyards.

The big thing you need to focus your time / money on is inspection- dimensional and magnaflux.

Last thing you want is some out of spec worn area or a non visible crack to destroy a multi thousand dollar build. And given the mileage, you never know how out of whack it is.

That'll also dictate what needs to be done (outside of the obvious wear parts). But I will say that machine shop work adds up quick. The machines are expensive and their hourly rate is generally much higher than your average mechanic.

 

Thats a tough one to answer.

A bit of history- way back in the day, MLS was the go to for big builds. Over time, that trickled down into lesser and lesser builds as popularity expanded. That's when the sealing issues really started.

First the lack of surface prep / machining was blamed. Then it was surface finish. Then it was not using copper spray, then for using it, then not using it on every layer. Then not pulling the layers apart to clean, etc etc.

Always seemed to be some excuse. Some people had zero issues, others with identical prep would. They just seemed very hit or miss.

Eventually people started getting tired of them and some pretty hard core builds started running traditional gaskets and had good success. Certainly a blow out was very certain if you got into knock (unlike with MLS which don't care), but as long as it stayed knock free and fueled right, some have had very good luck on regular gaskets.

I probably sound a bit bitter here and thats because I am. I'm frustrated that I spent the extra money, did the prep work 100% as directed at the time and still had a major seal failure despite not really pushing them at all (I never even went below a 3.0" on the M90). I've not had a single issue since switching back, so I hesitate to recommend MLS.

No doubt some people have had 0 issues on really high end builds. Others have had issues for near zero reason.

 

Yeah, the machine shop costs are definitely off putting for me. Pulling motors from a junkyard is something I'm also wary of, because I don't know the engines history. I can look it over on the outside for signs of leaks, and I can take the valve covers off and inspect there. But that still wont tell me how the engine runs, if the rings are shot, etc. As far as my 230K mile engine goes, I don't know its full history, but I do know that since I've owned it, It's been religiously maintained, it doesn't burn oil, and runs great. Would it be such a terrible idea to just leave well enough alone, as far as the bottom end is concerned? I can always pull an engine from the junkyard when the current one blows, or starts to show signs of failing.

 

IMO if the engine is out for machine work and you're already spending all the money for that rebuild project, it would be a bit crazy to just chuck it in with a stock cam.

Worst case its maybe $1k total in parts to do the cam also? If you found a used cam, maybe $750?

Even due to just ease of install, I'd rather wait the extra couple weeks or a month and get the cam in there.


No doubt I'm an advocate of getting it up and running rather than trying to tweak every tiny detail, and I'd certainly be all for just chucking the turbo on if you were leaving the engine in. But going through the effort to pull it and rebuild it, that's just begging for a cam.

 

The price difference is the easy justifier here. You can probably get 4 or 5 short blocks for the price of a single machine shop build.

Does your junkyard let you bring a battery? If so, perhaps you could have a friend jump the starter for compression and leak down testing? Certainly a thorough inspection helps, and looking at what kind of car / what shape its in helps too - especially since there were some L67 cars targeted to older markets.

I also always think back to some of the people who dropped $2-3k+ on a full blown rebuild only to have it come apart in less than 10k miles. Just don't want you to think the machine shop option is 100% certain either, especially since there's generally no warranty - especially adding a bunch of mods externally.

Not saying I'm totally against the machine shop route- certainly I'd be hypocritical to say that as its the route I went. It just can get expensive quick.

That's certainly one option. As long as compression is good and maintenance is up to date, its not a terrible idea.

Part of the question you need to ask is are you ok losing the money for everything internal to the engine? Its certainly in the mileage range that it could spontaneously fail. That could be as simple as a minor spun bearing or it could be catastrophic and ruin the entire thing - heads, cam, etc.

No doubt that could happen to any build, its just more likely with ultra high mileage.

 

There are multiple local pick-n-pull yards I go to, which don't allow batteries. I'd definitely be more comfortable with pulling a short block from a junkyard than paying the hefty machine shop bill.

 

That's frustrating, especially for something like component testing. It's not like you're trying to test drive the cars. But I get it, they're about 50/50 around here with the smaller local owned places being the ones who seem to allow it here and the bigger corporate places being against it.

Another thing that could help sway you a bit would be to to pop by one of your local machine shops to talk through it. Get a feel for their comfort level, what they suggest gets done to have a solid rebuild, and what it would cost. If they sound skittish about touching the 3800 in general or try to talk you into a $10k rebuild, that may help make the decision for you.

The shop I went to back in college was super competent and did all kinds of various race engines. The tough part was bounding what was needed vs nice to have. They'd love for you to drop several thousand and let them go nuts, but as a college student only working part time on a budget, I had to work through with them to get that list down to what was needed.

Granted I was also switching for ARP rod bolts and main studs and changing bore diameter .010 for pistons so there were quite a few things that required legitimate machining that were completely unavoidable that you may not run into.