Kevin Keenan
Registered User
Hi all,
I'm sure this discussion has been done before. Maybe done to death. As everyone says the crank is the weak link in the 4.2L stroker kit for the SC.
As far as I'm aware the stroker kit comes with a crank that has been modified to fit the 3.8L block because the journal diameter is different in a 4.2L. I would think that this would contribute to the steel crank being even weaker. But what about using a real 4.2L block?
Well, I'm rebuilding the motor right now and should have it running within the next week or so. My father-in-law was getting his van smogged and there happened to be a 4.2 block there that had a bent rod. The guy was ready to toss the block cause the 97 F150 owner that had his engine replaced never came to get it. So we took it.
I got a new rod and piston, and reconditioned the bottom end using the SC cam, and bolted on all my SC stuff. All the SC parts were used including the timing cover, water, and oil pump which are different in the 4.2. I used the lifter spring plates from the SC instead of the 4.2 plastic ones. Plus I am using the windage tray/stud girdle and balance shaft from the 4.2. This may also help alleviate stress on the crank as vibration usually kills a crank and the SC motor has none.
There are TWO hurdles with using the 4.2 block that we've come across so far. The block is not tapped for the bracket mounts to the block that stabilizes the lower intercooler tube. The place is there, just no hole. So we just drilled and tapped it. Worked out fine. The second is the timing pickup. Naturally since we're using the SC computer, and parts, (the harmonic balancer/crank pickup on the 4.2 is way different), we need to use the crank sensor pickup from the 3.8L. HOWEVER the 4.2 block is not tapped to hold the 3-bolt bracket that mounts the sensor. So we used a friend's mill and created our own out of billet aluminum. Looks pretty cool. Oh and the 4.2 uses LONGER head bolts so when doing this you'll need to order head bolts for a 4.2, not a 3.8.
Now the motor is almost done and another friend polished the entire engine (valve covers, plenums, SC, SC top, IC tubes, IC, Alt, A/C, head brackets, oil pan, EVERYTHING) to a chrome shine to boot. I should have it running by the weeks end, and will let you all know how it turns out. If you want to see some pictures email me as I am taking dozens of photos as the car is being completed.
Here is a list of what will be going on it that came off my old SC (minus the 3.8 bottom end work).
Autophysics 7" filter
Pro-M 75mm mass airflow meter
ZR Motorsports fresh air induction kit
BBK/Edelbrock 70mm throttlebody
Fully ported supercharger plenum
ESM 1.25" Raised supercharger top
Magnuson S-Model Supercharger
10% blower overdrive pulley
3" Extrude hone intercooler tubes
Intercooler fan
Dry Ice tray for IC
95 model year radiator
Fully ported upper/lower intake manifold
Lucas 42lb/hr injectors
Walbro 255lph fuel pump
ASP underdrive pulleys
Motorcraft platinum plugs
Motorcraft plug wires
MN12 EEC Tuner
Kooks mild steel long tube jet hot ceramic coated headers
2 1/2" downtubes- no cats
Flowmaster cat back exhaust system
Gutted Flowmaster resonator
McCleod custom 26lb lightened steel flywheel
Custom manual transmission with solid brass blocker rings
B&M Ripper shifter
Centerforce GOLD 11" dual friction clutch
3.55:1 gear ratio
ADDCO 1 1/4" front and rear swaybars
Kenny Brown strut tower brace
Kenny Brown lower engine cradle brace
Kenny Brown front suspension support brace
Kenny Brown rear torsional load brace
Eibach Pro-Kit 1.5" lowering springs
I'm sure this discussion has been done before. Maybe done to death. As everyone says the crank is the weak link in the 4.2L stroker kit for the SC.
As far as I'm aware the stroker kit comes with a crank that has been modified to fit the 3.8L block because the journal diameter is different in a 4.2L. I would think that this would contribute to the steel crank being even weaker. But what about using a real 4.2L block?
Well, I'm rebuilding the motor right now and should have it running within the next week or so. My father-in-law was getting his van smogged and there happened to be a 4.2 block there that had a bent rod. The guy was ready to toss the block cause the 97 F150 owner that had his engine replaced never came to get it. So we took it.
I got a new rod and piston, and reconditioned the bottom end using the SC cam, and bolted on all my SC stuff. All the SC parts were used including the timing cover, water, and oil pump which are different in the 4.2. I used the lifter spring plates from the SC instead of the 4.2 plastic ones. Plus I am using the windage tray/stud girdle and balance shaft from the 4.2. This may also help alleviate stress on the crank as vibration usually kills a crank and the SC motor has none.
There are TWO hurdles with using the 4.2 block that we've come across so far. The block is not tapped for the bracket mounts to the block that stabilizes the lower intercooler tube. The place is there, just no hole. So we just drilled and tapped it. Worked out fine. The second is the timing pickup. Naturally since we're using the SC computer, and parts, (the harmonic balancer/crank pickup on the 4.2 is way different), we need to use the crank sensor pickup from the 3.8L. HOWEVER the 4.2 block is not tapped to hold the 3-bolt bracket that mounts the sensor. So we used a friend's mill and created our own out of billet aluminum. Looks pretty cool. Oh and the 4.2 uses LONGER head bolts so when doing this you'll need to order head bolts for a 4.2, not a 3.8.
Now the motor is almost done and another friend polished the entire engine (valve covers, plenums, SC, SC top, IC tubes, IC, Alt, A/C, head brackets, oil pan, EVERYTHING) to a chrome shine to boot. I should have it running by the weeks end, and will let you all know how it turns out. If you want to see some pictures email me as I am taking dozens of photos as the car is being completed.
Here is a list of what will be going on it that came off my old SC (minus the 3.8 bottom end work).
Autophysics 7" filter
Pro-M 75mm mass airflow meter
ZR Motorsports fresh air induction kit
BBK/Edelbrock 70mm throttlebody
Fully ported supercharger plenum
ESM 1.25" Raised supercharger top
Magnuson S-Model Supercharger
10% blower overdrive pulley
3" Extrude hone intercooler tubes
Intercooler fan
Dry Ice tray for IC
95 model year radiator
Fully ported upper/lower intake manifold
Lucas 42lb/hr injectors
Walbro 255lph fuel pump
ASP underdrive pulleys
Motorcraft platinum plugs
Motorcraft plug wires
MN12 EEC Tuner
Kooks mild steel long tube jet hot ceramic coated headers
2 1/2" downtubes- no cats
Flowmaster cat back exhaust system
Gutted Flowmaster resonator
McCleod custom 26lb lightened steel flywheel
Custom manual transmission with solid brass blocker rings
B&M Ripper shifter
Centerforce GOLD 11" dual friction clutch
3.55:1 gear ratio
ADDCO 1 1/4" front and rear swaybars
Kenny Brown strut tower brace
Kenny Brown lower engine cradle brace
Kenny Brown front suspension support brace
Kenny Brown rear torsional load brace
Eibach Pro-Kit 1.5" lowering springs
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