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  • Building and swapping a LSx into an old Skier

    214 Skier
    • Year: pre 1985 Brand: Malibu Model / Trim: Skier Cost: $3500+ Engine Type: LSx 408

    I know the age old debate of LS vs SBC power goes on and on, for a variety of reasons I decided that I wanted to build a LSx for my Skier resto-mod project. What I'm hoping to cover in this thread is the build of the motor and the parts that are needed to bolt it up to a Velvet Drive, then how to install the set-up into an '84 Skier. To my knowledge this hasn't been done, so bear with me, I'll be figuring stuff out as I go. Tons of LSx swap info as far as cars go, in my mind I have it all figured out, but time will tel. I'm not gonna go into too much detail about actually building the motor, there are tons of books on LSx motors out there, but I know everybody loves a good motor build thread so I'll include a bunch of pics etc along the way.

    So the jist of it is I've got a 6.0L LQ4 (cast Iron) short block that has been bored and stroked out to a 408 or 6.7L. The rotating assembly is forged with ARP main studs and rod bolts, and Manley dished pistons with offset pins. This forged bottom end with the cast iron block is pretty much bomb proof, and easily capable of handling some forced induction at some point. There is a slight weight penalty with the cast iron block, 75 lbs I think, but I chose to use one for a few reasons, cost and strength being the two major ones. The LSx engines are awesome, you can go all the way from a 4.8L to a 7.0L (from the factory) in the same basic platform, they are extremely strong, have an unbelievable aftermarket, and the power to weight to size to cost ratio's are unbeatable. That being said I've be slowly acquiring parts over the past year or so to build this engine and I've finally got basically everything I need.






    I didn't build the short block, I was able to buy one built for me for basically the same price as I would have paid to buy the parts plus a few hundred bucks. I would have liked to do it, but the amount of time it takes to do it properly is too much for me at this point with family and work. The cast iron or LQ4/9 blocks dont have a provision for a timing chain damper, which I wanted. Trickflow makes an adapter bracket that bolts on to the cam retainer plate that allows you to attach as LS2 style damper, which is what I did. I used a Cloyes Hex-adjust timing set, I've had good luck with them in the past. The LS motors have thrust bearings in the front behind the timing gear to locate the cam. LQ4/9 blocks originally had a 24x crank trigger and cam trigger on the cam at the back of the block, I'm running a 58x crank and the cam sensor will be on the front cover like LS3's etc.

    I spent alot of time researching LS engine combos etc. Martin Smallwood at Tick Performance is a real cam guru. We talked for about 45 minutes on the phone and emailed back and forth a bunch. We came up with a top end setup and he designed a custom cam that will work for the power band I'm looking for. The cam specs out at 231/239 .631/.610 113+3. It was ground by Comp Cams.







    I tapped and plugged what used to be the cam sensor hole at the back of the cam, the hole doesn't need to be drilled I just ran a 1/2" npt tap and plugged it.

    The heads I got my hands on after much deliberation are some LS3 821 castings that have been cnc ported by Advanced Induction, there is obviously way more to it that just the numbers but these flow over 350 cfm intake and 220 cfm exhaust at 650 lift. Given the port volume they will be giving up some on the bottom end but should more than make up for that once they get flowing.



    You can see the porting work in these pics along with the work in the combustion chamber. The heads were milled once complete to 68cc chambers which is basically what a stock LS3 head measures in at.




    So once the heads were all ready to go I started with the measuring, the pistons ended up being around 0.009 out of the hole. I was looking to try to get around 0.030 of clearance and at the same time boost the compression ratio a bit with the thickness of the head gasket. I ended up going with a set of MLS Fel-pro's with a compressed thickness of 0.041 compared to the stock 0.051, which shrunk the compressed volume by 2.6cc getting me my 10.2:1. I then mocked everything up with light checking springs and checked piston to valve, which I wasn't expecting to be a problem given the cam specs and piston style but better safe then sorry.

    I'm running Brian Tooley Racing dual springs with titanium retainers, they are good to 0.660 lift. I like the insurance of duals over single beehive or otherwise, simply because of the cheap insurance should one let go.

    The lifters need to go in next, I got a set of LS7 lifters (really just the new style LS lifter) in LS motors the lifters are all roller lifters and they are held in place with lifter trays. I chose to drill some holes in the trays to aid in oil drain back. Given the sustained high RPM operation it is obviously better to have more oil in the pan as opposed to just sitting in the trays.

    Once all the checking was done, on went the heads for the final time, torqued the ARP bolts and there she sits. I measured for the pushrods and ordered a set of 11/32 0.120 wall rods with oil restrictors in them from Manton today, waiting on those to move ahead. The stockers are smaller and thinner wall, the extra weight does not really matter on the cam side of the valve train, stability is whats important here. The weight, or lack of it, on the valve side is what counts .




    So more progress, got the oil pump on, on LS motors they are driven off the crank. To put them on properly is a bit finicky using feeler gauges on the pump drive and gears to get the spacing right then snugging up the bolts. After the pump was on I put on the windage tray, which I had to shim up to get clearance for the stroker crank and rod bolts, I ended up using two washers on each stud. Then then oil pump pick-up tube went on. I measured the clearance which turned out to be just over an inch, way higher then I expected but after some research I found out that the Hummer H3 pan, which is what I'm using is supposed to have that much clearance compared to the usual 3/8" or so.

    I got the pushrods made by Manton, they are 11/32" rods with 0.120 wall, so nice and stiff, and given the sustained high rpm they put 0.040 restrictors in them so the motor doesn't pump too much oil up to the top of the engine. That's why the rods have the red marking on them. Below in that pick is the rocker stands.




    The LS3 heads use offset intake rocker arms to clear the larger intake ports compared to the cathedral port design. The exhaust rockers are the same as other LS motors except for LS7. The factory are nice steel pieces, very strong yet with a light tip weight. The only weakness on the factory rockers is the needle bearings, the needles aren't retained and there are cases when the bearings fail spilling small needles out into the engine. There are a few companies such as Comp Cams and Brian Tooley Racing that make upgraded trunion kits for the rockers with retained bearings and stronger shafts. So I got some Brain Tooley Racing rockers which are Cryogenically treated and micro polished with the upgraded trunions.

    I installed the pushrods, rockers, rear cover, front cover and valley cover. I got an aftermarket valley cover. The older LS motors use knock sensors in the valley of the engine, which I what my block would have originally used, you can see the two bosses for them in the earlier pictures, but since I'm running my electronics based on the 58x crank and forward cam sensor the knock sensors are different and located on the outside of the block.

    And there she sits for now, just gotta weld some bungs onto the valve covers for the PCV system, tap and plug some holes in the water pump, port match the intake manifold and I think she is pretty close to being all buttoned up.




    I've got the water pump mounted, I'm using a LS1 pump from a Camaro, most common engine accessory drive system spacing. I tapped and plugged the heater core inlet/outlet holes using 1/2 npt and 3/8 npt plugs. The Alternator is on, using a billet alternator mount was the easiest way to put the F body alternator onto the cast iron block. Only kind of issue I ran into was I had to drill and tap a hole in the block for the upper alternator mount bolt. All this stuff is available off of e-bay. I got a billet manual belt tensioner too, also e-bay, with F-body spacing, the LS tensioners mount to the water pump housing. Nothing too crazy going on with the accessory drive, I'm trying to figure out what to do for the raw water pump drive right now, I'd like to reuse my old one and make brackets for it, but haven't had a chance to mock it up yet.

    I've installed the motor mount plate adaptors, they simply convert the LS style four bolt pattern to the SBC style three bolt pattern. Because the boat originally had a Ford in in, I've had to order the engine side of the font mounts for the SBC bolt pattern form SKIDIM. They should bolt onto the adapter plates already on the motor now.

    Nothing special with the harmonic damper, just an F-body one, I really wanted to spring for a ATI of Fluidampr but just can't swing the money right now, hard to beat $70 for a stock GM one, at least to get me up and running.

    Waiting on some more parts, but I'm very close to mating the engine and transmission together on a stand.




    Been waiting on some parts and having a hard time finding time to work on the boat, parts are in though. I already talked about the adapter brackets from LS to SBC mount pattern, I ordered SBC engine mounts from SKIDIM, they bolted right up. Only thing I changed was I drilled out the tapped holes in the adapters and put 3/8" bolts in instead, there is just enough space for the head of the bolt. I ran into a problem with the bottom hole as it is blocked by the design of the mount so I have to find some 10 x 1.5 threaded rod to put into the block before the mount itself goes on.

    I was trying to come up with a way to attach a drain line to the oil pan to make oil changes easier. I couldn't find an adapter to go from the GM oil pan plug thread to 8an, its and oddball thread, so I took the pan off and drilled and tapped the drain hole with 3/8"npt and threaded in a 3/8"npt to 8an 90* adapter. I added about a couple of feet of hose with a female end installed, I'll be plugging that, then can easily add an extension for draining.




    All the threads on these LS motors are metric, so its a bit of a hassle to fit your typical 1/8"npt guage senders to the head and block for oil pressure and engine temp. I got two adapters off of eBay for cheap in a LS conversion set that convert the metric threads in both the head and block to 1/8"npt. The oil pressure pickup is on the back top portion of the block and the coolant temp sensor is on the cylinder head, the one for the ECU is front right, so I added my gauge sender to the rear left.



    So one of the issues is adapting the LS motor to the Velvet Drive. I haven't been able to find any info abou this so I'm flying blind on this part. I know that the old SBC bell housing will bolt up to the LS block so no problem there. The rear crank spacing on LS motors is 0.4" different then the SBC, however you can get conversion kits to mate LS motors to old GM trannies. The best, or what I think is the best solution was to get a Sachs 1050 flywheel, these flywheels bolt to LS motors however the way they are designed they take up the extra 0.4" spacing difference to in effect move the mating surface to the same position as found in the old SBC. The flywheel looks normal from the front, just really thick, but the back has a recess cast into it so its not that heavy. Once I had the flywheel I measured the mounting bolt pattern where the damper plate would be mounted too. From my Velvet Drive rebuild experience I know that both the 71 and 72 series Velvet Drives use the same size splined input shafts. So I went ahead and ordered a BBC damper plate with 8 springs in it as opposed to the 5 that the SBC plates have, it bolts right up real nice. In my mind this will all work perfectly, when I mate the trans to the bell housing...I guess we'll see.




    One of the things that I wanted to improve on was the factory PCV system, LS intake manifolds tend to ingest oil through the PCV system which leads to its own problems. So I'm adding two catch cans, one for the clean side and one for the dirty. I'll be plumbing the system with 10an lines to keep the air velocity low and using a fixed orifice style PCV "valve". I welded 10an bungs onto both the drivers and passenger side valve covers, the lines will run from the drivers side to the dirty catch can and then from that catch can to the back of the intake manifold where I am tapping a 3/8"npt port. I will add a 10an adapter to this port. I will tap the inside of this 3/8"npt adapter and thread in a plug with a hole in it, and bingo...fixed orifice PCV.

    The clean side with go from the air filter to the catch can and then from the catch can to the passenger side valve cover. Under normal conditions clean air will be sucked through this part of the system into the crankcase. However under heavy load, the blow by may, or will most likely, exceed the flow capacity of the dirty side, in this case there will be blow by flowing out what would normally be the intake or clean side, hence the two catch cans. There will potentially be also be a slight vacuum on the intake side as the air filter will cause a slight restriction under high air flow which will help suck out the extra blow by.

    The cans will be mounted side by side on the front of the cylinder head.




    I've got the transmission mounted up now, and I rebuilt all the mounts, the engine and trans are now sitting on a cradle on a dolly. Everything worked out just like I hoped with the flywheel and damper plate, the spline engagement on the input shaft to the VD is bang on. I gave everything a coat of paint before and after bolting it on to try to slow down any rusting of parts. The Bellhousing bolted right on, there is one bolt hole that doesn't line up but there are still 5 bolts holding it on. I checked to make sure the bellhousing was centred with in spec using a magnet base dial indicator mounted on the crank, it came out to a total of 0.010" total , but half that, and it's 0.005" which is fine.




    Next I started tackling the raw water pump, I was hoping to be able to re-use the one that I had from the Ford, it's a Sherwood G-21 a pretty common pump from what I can tell. I took it apart and ordered a complete rebuild kit with new bearings etc etc, after I realized it would fit. I took the mount off the Ford and just started looking for a place to mount it, as it turns out there is a mounting pad for where what I think was the A/C compressor on the side of the engine, and using the top hole of the pump bracket allows the pump to line up nicely with the 4 groove A/C pulley. I could hardly believe it. All I had to do was get a piece of 1/4 plate and drill three holes in it, two for the 10x1.5 bolts that go into the block and another for a 3/8" bolt that just pinches the mount to the plate. I painted it all up and bolted it on, seems pretty sturdy. I'll be able to use the 4 groove pulley on the damper and ordered a power steering pulley I'll put on the pump shaft.




    Just some pics of the bracket.



    The last thing I need to do to the intake before bolting it back on was to tap a 3/8" npt hole in the back of it where an existing vacuum hose barb was, I then got a 3/8" npt to 10an adaptor and drilled out the centre of it from the backside about halfway through the fitting. I then tapped this hole with a 1/4" npt tap and plugged the hole with a 1/4" npt brass plug. In this plug I drilled a 0.1065" hole, this hole is what will control the flow of the crank case ventilation, basically a controlled vacuum leak.



    Last night I had some time to get some more work done. I got the intake manifold bolted on for the final time and the steam vent plumbing run. The LS motors have the provision for steam vents in the cylinder heads, one at the front and one at the rear. From my understanding in the early years GM used all four from the factory, this changed to the two front ones in later years. There is much controversy over these steam vents over on the LS forums, the reason they are there is to.....surprise, vent the steam that could accumulate in the high portion of the coolant paths in the heads. After doing all my research I decided to use all four and route them into the low pressure side of the water pump, the road race guys seem to like to do it this way. When I was dealing with the heads prior to install I drilled and tapped each existing hole in the cylinder heads 1/8"npt and adapted it to 4an. To build the system I got a nitrous distribution block 4 to 1 and mocked that up on the top of the intake. Then ran lines from all four corners to the block. I had previously tapped and installed an adapter in the water pump too. So, when running the lower pressure on the suction side of the water pump will draw coolant from the cylinder head passages into the water pump, this will help eliminate any hot spots in the cylinder heads, and if any steam pockets develop this should pull them out. There are a few places that sell kits for this but I didn't really like any of them for the price. I know the plumbing is floating around right now but I will clean it up once I get the cover plate for the intake made.



    So I got my new marine alternator in, it's a 7si serries. I decided to take it apart to see how they do the ignition suppression. The only place that sparks are created is between the brushes and the rotor. In the 7si the brushes and rings are contained in a housing, the housing has a orange rubber seal on it, that's it, nothing else. So I took the cover off the back of my cs130-d and the plastic housing around the brushes and rings is pretty much identical. So, I'm gonna take that little orange ignition suppressor and install it on my cs130-d and bingo...I'll save the 7si for another project.

    Pics to follow.



    The manifolds are from a PCM, ZR 409, SKIDIM had them at the best price, not the best flowing, but real nice headers/manifolds are out of my price range for now. I know I will be taking a hit in the power department with these, but its all I can afford for now so it'll have to do, maybe upgrade in a few years to some nice Hi-tek one's.

    I'll have to modify one of the risers for an O2 sensor, but not a big deal.




    More stuff to follow. 


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    That's a lot of insight. We don't see enough engine mods, yet we spend thousands on tower speakers without even blinking   I can't wait to see that Skier on the water.  It's gonna scream!

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    Nice!!! I can certainly appreciate a good LS Build. You got some great parts and picked great people to work with like Tick and AI. Great write up and nice pics. Nice and clean and well thought out.


     Here's my current project, 347 LS6 with F1R Procharger in a C5:


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    "Well thought out" seems to be an understatement.  Love the details like drilling the pan to get a decent oil drain line.  So many things can just get overlooked and then you have those forehead slapping moments.  I hope the hull is worthy of this baby.

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    Thanks for the comments guys,  the C5 should haul the mail.  Its all together now, still some kinks to work out, gotta swap to a LS3 intake and flip it 180 for dog house clearance.  Runs pretty good but still gotta find time to tune the Holley EFI.

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    Great thread and Im late to the party, but just getting some time to look around the forum and this is a great thread.

    Full disclosure, havent read your VD71 buildup thread YET, but amazed you are able to put this much thru that trans without going thru clutch packs. 

    Great work "marinizing" this build. I didnt quite catch but am assuming this is a closed loop?? If so what did you do for an exchanger?? Along that line, just curious how you worked in the trans cooler as well?? 




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