4.2L Stroker with a REAL 4.2L block

[Kevin Keenan]

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

[Kevin Varnes]

The rear main on the SC crank is only 10 thou smaller than the standard crank. I don't think that is the main concern. The big concern is that the 4.2 crank is cast versus the forged unit on the SC engine. So far there has just been speculation whether the stock 4.2 piece would hold up. Looks like you will be the first to determine the durability of the cast crank. Good luck and let us know how it turns out!

[cudaz101]

No Damn Pictures...Talkin bout all dis bling bling...I like shiny stuff...Come on with the pix now...

Brad

[Vernon]

Sounds very cool but how are you going to get the oil pan into the SC? Did you mod the SC 3.8 pan to fit the 4.2 or what?

Vernon

[Aaron Pedroza]

Long time no see Kevin, sounds like a nice project, interested to see how it works out. Your last motor ran hard, hopefully this one will be a nice step up.

[SC Ward]

No problem fitting the SC lower intake,
with the balance shaft?
I'd have expected the SC intake was too low.

Interested in Vernon's ?, too.

If i read right, you're using stock 4.2L rods/ pistons?
What is stock 4.2L compression ratio?
Will it remain the same with single port heads?

Neat project;
Looking forward to reports on your results.
I hope it holds up allright for you.

[mannysc]

cant you delete the balance shaft , and use a 3.8 cam.
and wont the sc heads bolt on?

ive seen a 4.2 looks like a 3.8

[Kevin Keenan]

Hello,

Okay let me try and answer some questions.

Question 1 from Vernon. I used the 3.8L oil pan and pump pickup screen. The oil pan is a direct fit. The pump pickup screen needs to be mildly modified (bent) to fit around the 4.2 windage tray but it's no big deal. I used the 3.8 pump screen because it's bigger so I thought it would flow better. And I still am using thje 3.8 SC oil cooler too.

Question 2 from SC Ward. The balance shaft does not pose ANY problem for the SC lower intake. Yes the lower end is pretty much all 4.2 except the cam. I still used the SC cam because of the computer. Balance shaft is also included in some 3.8 like Aerostar and stuff. The shaft was designed to eliminate vibration in the motor. Vibration is a common cause of crank failure/breakage (even in SCs). So that's why I decided to leave the balance shaft with the 4.2. It came with it, there must be a reason. And it can't really hurt anything.

The rods and pistons are for 4.2. SC compression is 8.2:1. 97 4.2L is 9.7:1, however the dish in the 4.2 piston is virtually identical to the SC, except the SC pistons have little tails on the dish which might aid a slight in lowering compression. To stay on the safe side, as I break it in, I will use the stock blower pulley instead of the OD pulley.

And if you've ever looked at a set of 4.2 heads their combustion chamber IS VERY small; miniscule compared to the 3.8. I have three friends that PC game with me on weekends who are all Ford dealer technicians. From what I can see, and what they and my mechanic Tom (Sprint Mech, CA) tell me, almost all the compression is in the heads.

Finally to answer MannySC's question, yes the cam and the heads can be directly bolted to the 4.2 block. While the 3.8 and SC block are VERY alike there are differences. But see my posts about hurdles in setting up the 4.2. I wouldn't match a 4.2 computer and harness to a 3.8 cam and pickup. The shudders in the 3.8 harmonic balancer are every 120 degrees. The shudders and pickup for the 4.2 are vastly different. You must use the same computer, pickup, and harmonic balancer.

Here's a picture I took a week ago. The view is front with all the basics assembled. If you zoom in, you can see to the left of the timing chain that there is no 3-bolt pickup mount on the block for the the crank sensor. Like I said it if you want to see some specific pictures of the engine polishing or the engine itself simply email me. I have soooo many pictures it's hard to choose what to post. Right now the motor is complete and ready to put in the front subrame, have the tranny bolted to the back, and lower the car down and hook it all up. Will have more pictures this week.

[mannysc]

oh yeah whats the cfm requirments of this motor, i may build one when i get m y money.

[Kevin Keenan]

Sorry buy I couldn't resist, and because Cudaz requested too, Here's a quick pic of some of the polishing on my SC parts. It includes the intercooler, both side head brackets, valve covers, both intercooler tubes, and the upper intake plenum to the lower IC tube.

But I did everything else too including the A/C compressor, all mounting brackets, alternator, intake plenum, supercharger, water pump, oil pump, timing cover. I figured, it you're going to do some, why not all, otherwise it would look odd. I plan on polishing the heads and maybe the tranny too next time the motor is out.

Remember, polishing is NOT chroming. All it simply is, is making lots of tiny scratches in the same direction. We used JASCO to remove all the paint, and then sanded the parts down, then polished them. Straight sanding eats up sanding pads because the Ford paint is very hard. Especially the SC and tubes seem to have some very hard powder coating.

Don't forget to get something like Eastwood clear coat spray if you want to keep that shine without yellowing, or oxidizing!

[David Neibert]

Looking good Kevin...do you or anyone else know why the balance shaft wasn't used on the SC engine ?

I've seen several of the V6 mustang guys making around 350 rwhp on that block and the NA 3.8 using a stock crank, so I wouldn't be too concerned. Just get it tuned on a dyno before you try WOT.

David

PS: Are you using an SC knock sensor ?

[89xr7man]

THAT IS SWEET! NICE JOB. BTW, what did you use to do the polishing. Also, I'm thinking about porting the intake manifold, exhaust manifold, what do I need to do this....dremmel, air tool, etc...

What kind of gaskets did you use for the valve covers? Looks like a good seal.

[Rob Noth]

Kevin - the parts look sweet! I've been thinking about polishing some stuff while I have the engine apart, but I've been worried it would be too expensive to pay somebody, and too much work to do it myself! Can you give an idea of how much time/effort was involved in the polishing? What tools did you use? And how much would you charge?

BTW I work in Santa Clara, so that's pretty close to San Jose. We should have a "south bay" mini meet one of these days when the cars are all back together.

[Kevin Keenan]

I have a feeling that Ford decided to "tune" out the vibration on the SC without the balancer by using hydraulic mounts and such. I'm not sure. But if they use it in the 4.2 there must be a reason so I used it too! Not sure. Anyone?

Yes I AM using the knock sensor from the 3.8. It's tapped with an alan plug on the 4.2, simply remove and put your knock sensor in.

The polishing was not "difficult" per say, but more time consuming. Sand/Jasco off the paint. Fine sand, then polish it on a polishing buffer/wheel/pad. All the polishing took about 60 hours.

I would think to port the manifolds heads you can use pretty much whatever whether be an air tool, or dremel. Start with a coarse bit, but be careful the aluminum in the heads and manifold are VERY soft. You can always take more off, but once you've taken too much off you might be stuck!

I used a standard FelPro gasket set for SC.

Here's what I have so far. I just took this before coming home today. I have to re-polish it with some NEVR DULL as the pipes got a bit dirty from my hand prints and stuff while assembling it.

[Kevin Keenan]

My friend Pat did it for me as a favor since we've been buds for so long. I'd have to ask how much would charge if do it all. His hands are kinda "burnt" from working OT polishing to get the parts to me in time to put the motor together. Plus he works a 40+ hour week doing industrial A/C and cooling so he's usually pretty busy.

The tools were pretty much JASCO to remove the paint. Sanding and Polishing wheels and rouge compound for the polishing. Green works best, but blue is okay too.

Total time to do all this was about 60 hours, with him doing most of the work. With some help you could do it in the same or less.

What works best is if you have a wheel stand (basically a small motor on a stand that usually has a wire wheel on one side and a grinding wheel on the other. You can probably find polishing and sanding pads/bits to swap out and then do the job that way. Much faster than by hand!!!

Have a dremel or something handy for small cracks and crevices and the appropriate bits. If find some spare time and you want to come by the shop and shoot the breeze and check the polish job out for yourself to see if it's what you really want, give us a call at 281-4192. I'm usually there most weekdays til 5PM or so. We're just south of the Pruneyard down Union Ave. SPRINT MECHANICS, 356 McGLINCY LN #6, CAMPBELL CA, 95008.

If this setup works, we will be offering the crank sensor pickup bracket as a purchasable part for anyone who is looking to do the same!