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1991 3.3 Rebuild

4699 Views 127 Replies 9 Participants Last post by  donchicago48
My 91 Grand Caravan spun a rod bearing at 235,000 miles and 31 years. As luck would have it, I was 200 miles from home. I rented a UHaul Truck and Tow Dolley and towed the wounded vehicle home.
I began disassembling the engine in preparation for removal immediately. I found that the #4 rod bearing had spun and the#4 piston was hitting the cylinder head. All the other main and rod bearings looked fine.
The engine block had very little cylinder wall wear, about .003" - .004". There were no perceptible ridges at the tops of the cylinder walls. I decided to rebuild the engine myself except for machine shop operations.
Once the engine was out of the vehicle, I finished stripping the block of all parts and removed all the freeze and oil plugs. The camshaft and roller lifters were visibly worn. The pistons showed some skirt wear and the oil rings were fairly caked with oil deposits.
I pressure-washed the block and once all the oily grime was gone, I prepared it for an Electrolysis bath (see youtube) to clean the water passages. It did a great job of cleaning up all the invisible parts of the block. After about 48 hours of Electrolysis, I pulled the block out of the bath, pressure washed it again and treated it with WD40 Blast. I cleaned all the block threads with Taps and prepared to send it to a machine shop for cylinder boring and main bearing line boring (if needed).
Since there was only one 1991 block used for both 3.3 L and 3.8 L engines in 1991, I decided to have the block bored to 96 mm (3.780"). I found a set of 2007 3.8 L 96 mm bore flat top EUM Silvalite pistons that would work with my 3.3 L crankshaft and stock 6.18" rods. These pistons have 1.261" compression distance, the same as stock 3.3 L dished pistons. This engine will now be a 3.5 Liter engine with 9.7:1 compression.
I purchased a reground 3.3 crankshaft and matching main/rod bearings from Crankshaft Supply in Minneapolis, MN for $175. They provided fast shipping and excellent customer support. I recommend them highly. They provided a return shipping tag and refunded the $75 core charge quickly.
I found a reconditioned rod on ebay that was an exact replacement for my #4 Rod. It weighs almost exactly the same as the rest of the rods and has same forging number. I will weigh both ends of the rods and adjust weights as needed after the rods are reconditioned and fitted with new rod bolts. The new pistons will weigh more than the original ones, so the crank will need balancing.
I originally planned to use Hastings Moly Rings, but they could not ship before Christmas. Summit Racing customer support was excellent and arranged to cancel order from Hastinngs and refund my purchase price quickly. I found similar 1.2mm/1.5mm/3.0mm Moly Rings from Mahle on Amazon.
I ordered a new 3.8 L 4th Gen Cam, new lifters, valves, valve guides, valve seals, push rods, and rocker arms. I have not found new valve springs and will continue looking for a suitable replacement.
I will recondition the cylinder heads myself after the machine shop cleans and surfaces them. I also drilled and retapped the rocker shaft bosses for larger, longer bolts in order to help prevent rocker shat boss breakage. In the future, I may get later model cylinder heads, Intake and exhaust manifolds, and larger throttle body and air filter box.
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So, you said that you were going to use an NGC controller on the transmission?

If you draw out a design you need, I can convert it into a CAD file. Then you can order it laser cut for a lot cheaper than you'd expect.

My cousin does stuff similar, back-lit panels. I think he just paints over clear acrylic. The other option is to use an arduino to drive a servo for the Gauges, that's what I'm going to do for the display modules for these spacecraft simulator panels.
Audio equipment Gas Auto part Machine Automotive tire
White Light Black Electronic device Auto part
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I will take you up on that offer if I can't simply buy what I need to get this thing running.
Has anyone ever decoded the CANBus signals between the SBECx and the TCM/41te? I imagine I could use the Microsquirt to log the bus traffic. I have seen the status codes that the 41te reports, but not the operational codes. I have the revised TCM that Chrysler released in 2000.
I need to research more and consider all the alternatives before I get sny further down the road.
Automotive tire Automotive wheel system Automotive exterior Gas Motor vehicle

Bank One of Accel LS Ignition Coils

I will remove the extraneous wire from the Ignition wiring harness before this is ready to run. Now I have to figure out how to mount these brackets on the engine.
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Rectangle Font Automotive design Tints and shades Bumper

The UPS Driver delivered a number of goodies today. This item was by far the most interesting one. It will be a challenge to find a way to integrate this Engine Control Module into this build and take advantage of its many features and capabilities.
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Water Automotive exterior Communication Device Glass Rectangle

RACETRONIX Raw 1.0 Meter Fuel Rail Extrusion

I will use this Fuel Rail and a special Drill Bit to make new Fuel Rails to mount the Fuel Injectors for this build.
Office supplies Natural material Writing implement Wire Electric blue
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Automotive tire Rim Circle Font Gas

1990-2003 SBECx Cam Sprocket (left) and 2004-2010 NGC Cam Sprocket (right)

Note the difference in number and location of Cam Timing notches.
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Fuel Rails are cut to length and threaded with 3/8" FPT. I will send them out for polishing and anodizing once the Fuel Injector holes are drilled and the mounts fabricated.I will thread AN 6 Connectors on both ends. I will fabricate the AN Hoses for the rail-rail crossover, the supply lines, and return lines. I will plumb the Adjustable Fuel Pressure Regulator and Fuel Filter.
I'm installing new Copper-Nickel Fuel Supply, Return, and Vent lines from the Fuel Tank to the engine.
The Standard Fuel Pressure for this vehicle was 48 PSI. I will adjust the pressure as needed to tune the engine. I have a Bosch Fuel Pump standing by in case the engine needs more fuel than the stock pump can supply.
I'm installing a Broadband O2 Sensor at the new high-capacity Catalytic Converter Inlet and a broadband O2 controller with an Air/Fuel gauge to connect to the MS3Pro ECU.
I previously installed a 2.5" Stainless Steel Exhaust System from the old Catalytic Converter back with a large low-restriction Magnaflow Muffler.
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121 - 128 of 128 Posts