Illustrated rebuilding of a L36 into a supercharged 3800... - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 12-31-2006, 12:29 PM   #1
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Default Illustrated rebuilding of a L36 into a supercharged 3800...

Figured I would document this process for anyone who might be interested.

I'm starting with a 1996 Series II 3800 from a Pontiac Firebird (RPO Code L36). Purchased for $100. I'm not getting into the rational of why this is being done (please, none of the usual "you should go out and buy a L67.." stuff.) My intended purpose is to show anyone who may be interested what is actually inside the motor and how to take it apart and reassemble it, with some selective part substitution along to way to reconfigure it to a supercharged motor.

So, here'* day one: The motor was partially dissassembled when it was picked up, so there'* not alot to show taking off the intake manifold. The heads are easily removed, a 9mm socket is used to remove the rocker arms, while a 9/16th socket is used to remove the main cylinder head bolts. There are only two lengths..8 short bolts along the flange on the outside of the motor (4 per side) and 8 long bolts inside the valve cover area (again, 4 on eash side.) I'll cover the cylinder heads in a little bit.



On this motor, the previous owner had loosened the head bolts before draining the coolant. The end result is the orange sludge showing inside cylinders 2 and 4 in the photo. While a dumb thing to do, it could have been worse. Had it been water left in the bores, it would have destroyed the cylinder walls and required an immediate overbore and larger pistons.

As it is, this motor will need to be dissassembled to remove the rods and pistons and will probably need to have a new set of piston rings fitted at minimum.

Some differences between the RWD and FWD motors is evident as well. Note the position of the oil filter boss. That will need to be removed and replaced with one from a FWD 3800. Also note the oil pan shape, it has relief areas pressed into it for the the F-Body K-Member and exhaust manifold Y-pipe.

As to mounting the motor on an engine stand. You will need 12mm x1.75 bolts to connect the engine stand to the block. I'm using a mix of 90mm, 100mm, and 120mm bolts to do the job. Flat washer are also needed to keep the motor level on the stand, as bottom left transmission bolt (when viewed fro the rear of the motor) is set up with a locating dowel. The washers make up for the lack of the dowel on the other side of the motor.
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Old 12-31-2006, 12:44 PM   #2
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Quick comment before you continue...

The pic above perfectly illustrates why everyone yells "Drain that oil!!" as soon as someone suspects a UIM failure. Looks nasty already, don't it? Imagine letting it sit for a while.

Thanks for the time, and I look forward to the rest of this story!
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Old 12-31-2006, 01:41 PM   #3
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This is gonna be a neat thread.
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Old 12-31-2006, 01:52 PM   #4
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Yay, a good photo writeup. You've seen mine about an LN3?
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Old 12-31-2006, 03:33 PM   #5
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Very Nice Curt.. Interested to see the process

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Old 12-31-2006, 04:05 PM   #6
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Quote:
Originally Posted by MOS95B
The pic above perfectly illustrates why everyone yells "Drain that oil!!" as soon as someone suspects a UIM failure. Looks nasty already, don't it? Imagine letting it sit for a while.
Exactly, but there'* a better illustration yet to come....

So, with the heads off, it'* time to start taking down the front of the block, starting with the water pump. Here is the front of the motor and the 4 8mm bolts holding the pulley on. If you happen to have the accessory drive belt on and with tension, it'* pretty easy to remove them. Without a belt, use a box wrench and a rubber mallet to loosen the bolts. (A quick, accurate, whack on the end of the wrench will pop the bolt loose with just your hand holding the pulley still.) Note, while the bolts are marked metric 8mm, I found that they are a bit undersize. An SAE wrench fit the heads better (tighter to the flats.) You run across this a lot in mass produced bolts. Just because it is supposed to be metric, doesn't mean that an SAE sized wrench might fit the actual head better. Don't be afraid to use the wrench that fits best, regardless of the markings.



OK, water pump pulley is off and in the pile of parts to be cleaned. Next stop, the water pump itself. Note how clean it looks...it'* almost certain to be a replacement part. This is actually a good thing, it'* seals look good and the impeller spins smoothly with a little bit of drag. Previous owner probably though the coolant leak was because of a bad pump and replaced the wrong part. His loss is my gain (little payback for him screwing up the cylinders.)

To take the pump off, there are two SAE bolt sizes used around the perimiter of the pump. Don't worry, you can't screw up and confuse them on reassembly as the larger ones are long enough to pass through the timing cover and into the block.





OK, pump is off, need to make a little working room around the harmonic balancer. So the oil filter boss/oil pressure sensor plate needs to come off. No sweat, 4 SAE bolts of identical length are used to hold it on. Once out, a little tap with the rubber mallet will unseal it from the block. Don't go overboard, theres two loose parts inside that you don't want to loose.



Oh H***. Inside the cover looks like a mess. That nugat looking crud dripping out of the oil cavity is a mixture of Dex-Cool and Oil. This means that the entire block needs to be stripped down and cleaned, as this goo is inside the oil passages in the block, and may be in the bearings as well. Only way to be sure is to strip the block down and inspect the parts.



Now for the real fun. The one bolt torqued to a gazzillion ft-lbs. is the harmonic balancer bolt. To get that monster out, you need either the Air Impact wrench from h***, or a 4-foot or longer breaker bar. Either way, the crank has to be locked down to keep it from moving. The easiest way of doing this is to put the flex-plate on, then slip a steel drift punch through one of the Torque Converter mounting holes. Rotate the engine until the drift is wedged tight against the starter mounting pad on the block, and the engine stand. That will lock the crank in place while you wail on the harmonic balancer bolt.



Once the "Bolt-From-H***" (tm) is out, a Harmonic Balancer puller is used to draw the balancer off the crank nose. This one came off quite easy, though a deep socket had to be inserted into the crank nose to give the puller something to work against (Mine is a typical V8 style puller.)



Balancer off, lip seal and crank nose look good. Note the splash shield around the reluctor sensor. This is a plastic piece that just pops off the three studs with a little prying with a screwdriver. I don't know if this piece will fit older 3800'*, but it'* worth looking into. (If you've ever flooded the crank sensor on your Bonneville, then you know first hand how well they don't work if the get wet )



Ok, down to the timing cover. This is a good place to pause. The next part to come off will be the oil pan as a prelude to removing the timing cover.
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Old 12-31-2006, 08:28 PM   #7
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nice glad to see your tackling this and documenting it...i just skipped on to the big stuff in my documentation...

a couple words of advice...

for maincap/crank removal remove the slugs from the bores remove the 6 sidebolts on the main caps and remove all the main bolts and just thread each in about 2-4 turns then wrap a rag around the sides of a 2x4 and rotate the crank so that you can place the 2x4 across the crank counterweights in the cyl 1,2 and 5 & 6 bores and smack it with a hammer...took about 2 whacks in each hole (while rotating the crank so your only hitting on the counterweights while alternating which bore you put the 2x4 in) for me to flip the engine over and easily remove the maincaps...

before you get your block machined/hottanked you may want to tackle some of the same stuff i have with drilling the mains oversize to 3/8ths on 2,3,4 mains to remove the restriction from the cam bearing shell'* intruding on the main oiling passage as well as porting the oil pump housing in the front cover/oil filter adaptor.
3800 Oiling Tech

you may also want to look into unshrouding the valves by relieving the cylinder bores and combustion chamber for more low/mid lift airflow
Let it flow, let it flow, let it flow

i'm doing quite a bit more than the links i posted so if you want to know what i'm up to dont hesitate to contact me...

Regards, James
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Old 12-31-2006, 11:36 PM   #8
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Quote:
Originally Posted by jr's3800
Very Nice Curt.. Interested to see the process
Here'* some more....

I forgot to photograph the Harmonic Balancer comming off, so I hopped over the the 2000 L67 and pulled it'* balancer...

Procedure has been described before on the forum, use three M6-1.00 bolts with 1/4" fender washers. In my case, the bolts are 70mm long. I also had to use a deep socket inside the crank nose to give the puller something to push against. (Mine isn't long enough to reach the bottom of the hole on it'* own.)



Ok, with the balancer off, time to get some stuff out of the lifter valley and mark the pistons before turning the block over to remove the oil pan.

Here'* the lifter valley, the balancer shaft runs up the middle. On either side is the row of roller rockers and the plastic retainers that keep them running straight in the bores. Take the four bolts out and remove the two lifter retainers:



Now with the retainers off, time to pull the lifters out of the bores. Note more of the oil/coolant spooge in the tops of the lifters. The tool in the photo (attached to the #3 cylinder lifter) is a gizmo for pulling lifters. It goes into the top of the lifter, tightens to expand the tip, and hooks the clip slot in the top of the lifter body (more on this later when we take apart the lifters for cleaning.) Built into the tool is a slide-hammer to tap out the stubborn lifter.



Here'* a better snapshot of the entire tool attached to the lifter being pulled



Finish removing all 12 lifters and set them aside to be cleaned and inspected later.

Now, here'* an important step. You need to mark every piston part BEFORE you remove them from the bores. You also need to mark them in a way that you can install them correctly, not upside-down. The reason is simple. Every piston is made with a thrust side and is supposed to be installed facing a particular way relative to the direction the engine rotates. Once the new pistons are in and running, they wear a little to match the bore they were installed in. On installation, the piston needs to be installed in the same bore it came out of, and facing the same direction.

The best way to do this is to punch a number into each piston crown. I am also going to punch the same number into the rod and rod cap in a little while, but doing the crowns now with the motor right-side up is easier.

I may end up replacing the pistons and rods later. A big part of that decision will be the condition of these pistons once they are out, cleaned, and inspected. Cardinal rule of engine rebuilding: Never throw anything away until you are certain it'* bad AND you have the replacements installed. (even if these prove to be junk, you still need to take some measurements off them for replacements.)

My daughter Carolyn took over camera duty while I stamped the pistons...



And here'* the #2 piston crown with the "2" clearly stamped into the crown at the top.



Ok, thats it for today. We'll pick up tomorrow with the motor flipped over for removing the oil pan. Time to get cleaned up and celebrate a new year.

Happy New Year Y'all !!!
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Old 12-31-2006, 11:41 PM   #9
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Are you going to do a good write up in the tech info on this. I am sure this will be a lot of help in the future.
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Old 01-01-2007, 12:07 AM   #10
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Quote:
Originally Posted by myfirstbonnie
Are you going to do a good write up in the tech info on this. I am sure this will be a lot of help in the future.
Don't know, we'll see how this turns out. Anyone on the list can feel free to make use of the photos in future as reference, or if a picture of a certain area of the motor is needed for discussion in another thread.
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