nw4230

Hey guys, been lurking around these forums recently and just started an account, so hi. o/

I just bought a 1995 Buick Roadmaster Wagon with an LT1 (she is the "Land Spruce Goose," and yes, I do have wood grain). The car has 139K on it, and the engine is pissing about a quart of oil a minute onto the exhaust. I have some time now, and I want to rebuild the engine. As I'm pretty new to engine work, I'd like to make this my learning/build thread.

I bought this book:
...as a guide to refer to. A review says it's great if you want to rebuild to stock specs.

I want to stick with N/A and pass emissions (not a big truck fan, so I want to use this as my tow/haul/family mobile). From what I read, high compression builds are recommended for the LT1, reverse flow cooling facilitating that.

260 HP stock, I guess I'd like to be around 330-350.

So I've got some questions to start off:

1. Elephant in the room: would an LS swap be a better idea (I might just want to rebuild the LT for the experience)?

2. What kind of modifications am I looking at for the bottom end, heads, pistons, etc. to be able to make 330-350 and pass emissions? Fuel economy is a concern, but less so than power and smogability.

3. I read that one should start at the back and build up to the engine. Would the stock 4L60E and LSD be able to handle the modded engine, or what kind of upgrades would you guys recommend? I was reading this page: http://etereman.com/blog/general-mot...ion-for-towing

Thanks in advance, hope to give back to this forum some day when I'm not so much of a newbie.

Catmaigne

iTrader: (6)

Oil dripping onto the exhaust is probably just a leaky valve cover gasket. $20 and about 10 minutes of your time.

If the engine was maintained and not beat on then 139k isn't crazy. If you can verify that your oil pressure is good with a mechanical gauge then I wouldn't bother rebuilding it, I would be more worried about the transmission. The 4l60e isn't too fond of torque combined with heavy cars.

330hp at the flywheel can be done with simple bolt on mods for <$500. The biggest hurdle would be passing emissions.
-Bypass the throttle body because it's free
-Remove the home plate and plug the hole in the elbow with a hockey puck
-Get a piece of 3.5" exhaust tubing and run it from the elbow to a 3.5" to 3" reducer on the MAF sensor
-Swap the paper filter in your airbox for a fiber one (K&N, Spectre, etc), then swiss cheese the airbox (and also little drill holes in the bottom so water can drain)
-Next you will need some exhaust work and a tune (or else it will run like crap). The stock system is very restrictive with 2 mufflers, 2 resonators, and 2 cats. We went with generic Summit long tubes on my friend's Roadmaster because emissions wasn't a concern. From there it went into a 2.5" X pipe, Dynomax super turbo mufflers, and dumps before the axle. Finding b-body long tubes with emissions is going to be expensive whereas the Summit LTs were only $250 (and coated). If you can't find emissions LTs then you're limited to those awful shorties which I don't think are worth the money or time over stock manifolds. Running cats will also cost you some power.
-You can also run an electric water pump but the power gain isn't a whole lot

My friend's T56 Roadmaster made 295rwhp on a Dynocom with all of the mods listed above. Those dynos have a tendency to read a little bit higher than a dynojet but I think the numbers were still pretty close. That's right in your ballpark of 330-350 flywheel.

As for the diff, check your RPO codes because you might already have a posi. If not, you can grab a 3.08 or 2.92 G80 rear out of a b-body with tow pack or some cop cars. If you can find one with an Auburn LSD that isn't totally fried it would be worth rebuilding with 3.73+ gears. Yukon also makes a duragrip LSD carrier that is only around $350~.

stevo9389

I wrote almost the same thing about the engine so I will spare you the repetition.

The back of the intake is also prone to leaking so check that too because it is just the cost of a couple intake gaskets and some RTV to fix.

As far as your questions go:

1. You wanted a family car that can tow/haul so sticking with the LT1 platform will get the job done and then some. To swap motors would require everything from the transmission forward from the donor car plus a k-member making the job expensive for just a modest boost in stock HP/TQ. Stick with it until you want a race car with an infinitely larger aftermarket.

2. We do not know where you live so any advice about swapping motors or just modifications in general could automatically make your car illegal for highway use or at the very least force you to bribe someone to overlook them. Last I checked, the shop can risk north of $10,000+ in fines for doing so.

3. The transmission and converter are a great place to start. I have never owned a 4l60E before but second hand experience from friends is to never cheap out on the converter or the rebuild (unless you like throwing away money). You will also want a trans cooler and probably a temp gauge for it too.

96capricemgr

iTrader: (1)

The wagon axle is wide so you can't just swap a housing from another b-body.

350hp and a peppy tow haul rig the LT1 will be a better way to go. It has more lowend and is already there. 139K miles is just broke in, if it needs a rebuild at that it was horribly abused.

Far as the tranny, one can go 200K and survive behind modified engine with just a Transgo kit, the next car it dies at 100K miles of grandpa driving. It is 20yo, we have no idea what you have, but the 4L60E is plenty capable if assembled right.

Figure out what seals and gaskets need repair, might as well do a full tuneup, cap/ rotor/wires/plugs all at the same time as gaskets.

Then look at things like exhaust, unfortunately wagon tailpipes are a tough nut to crack, one shop I would not do business with was trying to make larger tailpipes, maybe he succeeded but the variation car to car was bad. For a mild build you can probably keep the stock pipes, by that far back the exhaust has cooled and shrunk a lot, it can definitely benefit from new intermediate pipes and mufflers.

3.42 gears would be perfect if this is a highway family trips car, 3.73s are good if spending less time on the highway.

I had a few of these with 2.56 and 2.93 gears. With the 2.56 overdrive hurt mileage unless a level 70+mph cruise. Even with that crap gear the guy who bought it for a demo derby car(rotten floors) was shocked at the power. The b-body LT1 packs a lot of torque at low rpm.

Fresh valvesprings will let it make power probably 800rpm higher than it does now.

Far as a tranny rebuild. Money does NOT equal a good rebuild, the shops that throw the fanciest parts at even mild builds are often the least competent. For an application like your's if someone mentions kevlar, billet, 5pinion etc. they may well not know what they are doing.
The 4pinion planetary in the LT1 cars is SOLID, in the 80s there was a problem and in the 2000s they realized they could make 5pinion powdered metal cheaper than the 4pinion forged the LT1 cars have. If something is worn and needs a new planetary the new 5-pinion is fine but it is NOT some giant upgrade. Even the beast sunshell which was developed to resolve a real problem is not going to be necessary for a build like yours. I still run a stocker.
If a shop tries to sell you a "Vette servo" that is suspect because the LT1 cars all got it stock.

There are a LOT of very bad 4L60E builders out there.

nw4230

Thanks for the comments, guys.

I forgot to mention some pretty important stuff yesterday (sorry, late night at work):

1. The valve covers are weeping a bit, but not leaking (and neither is the intake manifold). The oil is a steady stream.

2. It was a "little old lady from Pasadena" car and well maintained until she died. Her son abused it pretty bad, and #8 piston is cracked.

3. Previous mechanic screwed up a head gasket job, and they are leaking again. For some reason nobody replaced the piston.

Thanks for the bolt-on suggestions, Cat. Obvious reasons for a rebuild, I guess, haha. Although I'll mainly be using the car for towing and hauling, I'd like to have as much fun with it as I can. Eventually planning to beef up the suspension with 9C1 stuff, poly bushings, etc. as per stuff I read on the Buick forums.

If it's that easy to push 330 HP without engine internals, what kind of HP can I expect to get from your average 11.5:1 build?

The car has the tow pack (inc. G80), so 2.93 posi. I take it that 3.42 would make it a more capable towmobile with not too much a hit to fuel economy? As I understand it, a higher ratio will result in higher engine rpms, but more torque at the wheels.

I'd do all the tranny work myself; was looking at these kits:

1. http://www.ebay.com/itm/4L60E-Transmission-Rebuild-Kit-Shift-Kit-Heavy-Duty-Sprag-BEAST-1993-1996-/170814820430?pt=Motors_Car_Truck_Parts_Accessories&hash=item27c55b504e&vxp=mtr
2. http://www.ebay.com/itm/Trutech-Ultimate-Towing-rebuild-kit-1993-2003-4L60E-Raybestos-Blue-Plate-and-GPZ-/261311489367?pt=Motors_Car_Truck_Parts_Accessories&hash=item3cd760e557&vxp=mtr
Open to any suggested kits. Tranny also shifts very hard from 1-2, so I'm guessing an accumulator piston is busted. Everybody recommends the Transgo shift kit for it, so I'll get a rebuild kit with one. The Buick forums say that the car can tow 5000 lbs, or 7000 lbs with a weight distribution hitch, and I'd like the tranny to be robust enough to handle that for 200K miles or so, in addition to not dying from the high output of the rebuilt motor.

I guess I want a sleeper-mobile. Do you guys think a high compression build could pass emissions through moderately modified exhaust (high-flow cats, larger pipe, etc.)? I was thinking of installing exhaust cutouts.

BALLSS

My $02 on the tranny is get a good local shop if you can. Easier to deal with any problems than chasing a ebay tranny, IMHO A good shop can build a tranny for towing. I just had one built for my Ford truck..

3:42 gears would be a good overall gear

since you are rebuilding motor, get a cam that makes good low/mid range TQ. Heavy car and towing you need TQ. You can use stock heads with something like a Crane 227 cam with 1:5 RR and 10309 springs. A mail order tune from a reputable tuner and you would be in the 325 hp range no problem. Get a H/C package from someone like Lloyd Elliott and make even more.

I had a bolt on baby cam & mild port job on AL heads and made 350 RWHP & 352 RWTQ. Car idled like stock and passed emissions easily.

Catmaigne

iTrader: (6)

Check the breakaway torque on the Aurburn carrier that's in the car now. If someone was driving it hard then it's probably done. Also, I completely forgot about the difference in diffs between wagon/sedan. 96 is right, you would only be able to grab a rear from another wagon for a direct bolt in.

The difference between 3.42 and 3.73 at 70mph on a stock tire is 2000 vs 2200 rpm. I would go with more gear, especially considering the added weight of a wagon. Choice is up to you.

I've never been too keen about altering the valvetrain on the iron heads without machining them for screw in rocker studs. The stock press in studs are going to be much more likely to pull out of the heads with aftermarket cams/higher rocker ratios/increased spring pressures. Also, I don't think it would be worth it to have the iron heads machined when you can buy a used set of aluminum heads for pretty cheap and shave some weight up front. The flow difference between the two is nominal but aluminum is more suited for high compression.

nw4230

Thanks ******, but I have a good bit of space and a couple months to devote to this project, so I'd like to rebuild the tranny myself. Plus I just finished up on a shitty AX4N on my friend's Taurus, haha.

A set of heads from Lloyd Elliot would have better flow and a smaller combustion chamber, which would boost compression, right?

Is this the camshaft you were talking about? http://www.summitracing.com/parts/crn-110901

Do I need to get a forged bottom end? Also, I see a lot of endorsements for the Mahle Pro Pack pistons - what do you guys say?

Other than a beast sun shell, upgraded bands, clutches, shift kit, HD converter, is there anything else I should change in the tranny to handle 350-400 at the wheels?

Cat, I've been looking at used aluminum heads on eBay - I'll snap them up soon. How do I check the breakaway torque on the carrier?

Somebody suggested that I get a 13-bolt differential carrier to handle the higher output from the engine - what do you guys think?

So to change the differential ratio, I just change out the pinion and ring gear, right? Examples here: https://www.rockauto.com/catalog/x,c...parttype,10438

Also, why does it say that the 3.42 and 3.73 are "Standard Gear"s? I thought the standard towpak on B-bodies were 2.93.

BALLSS

Op

if you have the tools and skill set to build the tranny, great.

for the kind of HP you noted (assume RWHP) a mild cam and AL head port job will get you 350 at the wheels and with the right tune be smog compliant. If you are buying a used set of LT1 AL heads than just send them to Lloyd Elliott and have him spec a custom grind cam or your use intent (low TQ, heavy car, towing)

The cam you link to is not what I mentioned if staying with stock iron heads and 1:5 R (not 1:6). The crane "227" was used by many back when the LT1 came out in the B-bodys

you can get a custom grind cheaper than what Summit sells it for

http://www.summitracing.com/parts/cr...make/chevrolet

for the HP you are looking for you don't need a forged bottom end. If you do need to go .030 over to clean up cyl than the Mahle piston you note is a good set. Get crank polished (or ground), new set of bearings. stock oil pump and have ARP fasteners put on resized stock rods

if you want to keep ABS than you need a ABS pinion gear. 3:42 is what I would get. I don't think you need to go another rear end. the 8.5 10 bolt is fine. Look into a Eaton LS diff when you do the gear swap. If you have trouble finding the ABS reluctor for 3:42 gears, Bob Shirley on the Impala forum has them. I don't think the Doorman gear set you listed is ABS. AAM, Motive, Precision gear are all good brands. AAM is factory (American Axle Marine)

If staying with iron heads ask Lloyd for a cam and spring kit

Catmaigne

iTrader: (6)

Lloyd's heads will actually have a larger combustion chamber than stock from un-shrouding the valves. A thinner head gasket will boost compression and compensate for this.

You're better off grabbing a set of aluminum heads from the forum classifieds here, LTXtech, LS1LT1, CamaroZ28, local Craigslist, etc. Prices on eBay are inflated most of the time. You can usually get a set for $150 with under 100k, no sheared bolts, no cracks, warping or any other funny business. Castings 374 and 643 are more desirable for porting than 561.

The 8.5" 10-bolt is pretty stout as is, the only weakness is the stock Auburn carrier (not rebuildable). Get the rear wheels off the ground with car in neutral and have a friend hold one wheel in place firmly. If you're able to turn the other free wheel easily then that would indicate that the clutches in the diff are toast.

96capricemgr

iTrader: (1)

Thinner gasket than the stock b-body .029? The popular .026 won't do much, a few guys have tinkered with modifying old school gen 1 .015 steel shim gaskets.

Catmaigne

iTrader: (6)

I was taking about for the aluminum heads. The same impala gasket will probably yield mid 11 cr.

nw4230

OK cool, I'll keep an eye out for a good set of the desirable castings and call up Lloyd and AI later today to ask about porting.

OK, now to get started on the rear end. I'm looking at the Eaton Diff Application Guide. They offer two LSDs: Detroit Truetrac and the Posi. I'm guessing the Posi is the way to go, as the Truetrac does not seem rebuildable, yeah?

I read several posts advising not to install the posi myself. Eaton provisdes an installation manual. Is this something a garage mechanic could do?

I think the correct Eaton Posi part is 19559-010. It's for GM passenger cars 1988-1996, GM 10 bolt C-Clip, 8.5"/8.6" ring gear diameter, 1.32" axle shaft diameter, 30 spline, and 2.73 and up gear ratio. From what I see on the Buick forums, this seems to match - any confirmations would be appreciated.

The list of other stuff:

1. 3.42 ring and pinion gears, plus ABS reluctor
2. The Eaton Application Guide says "All Eaton differentials made for General Motors 8.5" and 8.6" axles require special bearings." Do you guys know if the race O.D. is supposed to be 2.89" or 3.06"? Says that pre-1999 are usually 2.89, and suggests part numbers for both which cost about $20 on Amazon (bearing + race).
3. Do I need anything else? RockAuto lists a kit for the diff: https://www.rockauto.com/catalog/mor...780&cc=1022184

Thanks as usual, guys.

nw4230

Oh, almost forgot a couple things:

1. I assume I need a Hypertech programmer or equivalent to get the speedo to read correctly after jumping down to 3.42:1.

2. I keep forgetting to mention this: horribly enough, I live in California. Only one tiny rust spot, but I take it that it'll be a lot harder to get the built motor to pass emissions.

BALLSS

OP

setting up gears is something I don't do. IMHO if you have not done it have a qualified shop do the Eaton & gear install. Should be around $200 if you supply parts.

Not saying you can't install them yourself but aside from experience you do need some mic measuring tools and you will need a press 9or have it done) to get the reluctor gear on your pinion shaft

check outer axles for bearing wear...often a surprise on gear/diff swaps. Use the Felpro diff gasket vs stock (it has the 2 holes to allow gear oil to get to outer axle bearings. Use dino 80-90 wt gear oil and Ford LS additive for the Eaton. Not synthetic oil

I have the Eaton LS 400 lb spring diff.

The Eaton does require a different bearing kit than the stock unit. The link you sent does not say what size/application it is for so just confirm it is for the Eaton

It is often referred to as "master bearing install kit"

for a mild H/C build like yours don't get a Hypertech. Ed Wright can do a mail order tune and you should pass Calif. emissions easily if the car is mechanically sound with a good tune

Don't go high stall on TC if you are towing

ahritchie

iTrader: (1)

Hypertech programmer sucks.....just get the PCM tuned, it will actually gain HP and change the transmission programming noticeably, and fix the speedo. It's not that expensive (less than $150) The hypertech programmer is useless other than to fix the speedometer.

You can forget about long tubes being in California though....look for CARB legal shorties. There's plenty of smaller cams that should pass emissions out there. Some people STILL have issues passing though. You might be better off to just leave it mostly stock and add nitrous since that state makes it so difficult to pass with any serious mods IMO.

Catmaigne

iTrader: (6)

The truetrac is a worm gear carrier that is rebuildable but it doesn't wear out like regular clutch posi. I would avoid the truetrac though, there's a reason they call it the truecrap.

We needed a special set of carrier bearings when doing the Yukon in my friend's Roadmaster sedan. Not sure if you would need them for the Eaton.

If you've never done any diff work before then I'd stay away, very easy to screw up. Biggest mistake for first timers is not having enough shims stuffed in so the carrier shifts axially and everything goes out of whack as soon as it's under load.

BALLSS

if you don't go to big on the cam and have a good tune you can pass calif. smog

Lloyd can sec a cam that will pass or there are a few off the shelf cams that will pass

also in Calif we only get 91 octane

yeah long tube headers will not pass visual.

CARB certified shorty headers will.

Op is just looking for a 350 HP build so that should be no problem with a good tune to pass emissions. Will need to keep CATS and have CARB certification for any aftermarket intake if he does that also