3.8L SC to 4.2L SC - TCCoA Forums
 
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post #1 of 17 (permalink) Old 01-08-2004, 09:55 AM Thread Starter
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3.8L SC to 4.2L SC

Hey, I've got a 3.8L SC sitting. It has 200K miles on it. It's been a PITA to sell. I am looking at doing some projects. I looked at many of the discussions of the 4.2L (Thanks PJ) and wondered besides money, what it would take to rebuild the 3.8L SC into a 4.2L SC.

I am researching a different intercooling system for the SC. I want something I can drop into a LX body.

Think we can have a technical discussion on this? I know it's a limited application, but I think I'd end up with something that is torquey as all get out, and still have decent milage.

The Parts Bin Special is DEAD! It is being parted out.
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post #2 of 17 (permalink) Old 01-08-2004, 10:50 AM
 
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well, here's a good place to start getting ideas... http://www.moranav6racing.com/stroker.html

the only problem with the 4.2, i dont believe anyone really produces a forged 4.2 crank. personally, i wouldnt build the stroker or use the 4.2 with an eaton without a forged crank. so there is one custom piece right there. -greg
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post #3 of 17 (permalink) Old 01-08-2004, 04:03 PM
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the ford 4.2 crank is the strongest out on the market. Anything from Morana is not worth crap on an eaton blown engine. Someone made a custom built 4.2 forged crank for 2000 dollars and used that in an sc engine. That's the only way I'd ever stroke an sc engine.
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post #4 of 17 (permalink) Old 01-08-2004, 05:17 PM
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I talked to a machine shop that quoted me a price on a billet, and a forged crank, the billet was like 2100, and the forged was about 3400.

I'm debating the same upgrade to my SC motor, would love to have the low end torque, but not sure that I want to fork out the 3K for the kit, and then another 2K for the crank. with those prices I could get Coy Miller's shop to build me a Stage II engine and have it Dynoed.....and it would still be a 3.8L

1997 LX Sport 4.6L 2.73 , MODS=SCT tuned/J-Mod/Trans Cooler/Dyno max Cat-Back/NgkPlugs/Mac cold air/March UD's/FRPP aluminumcarrier3.73's(spare for strip use)/ PI cams + PI intake manifold w/adapter plate/ Mark VIII Convertor/80mm L-Maf/70mm TB/ Mark VIII 1 piece shaft/Cobra R' wheels/ Kumhos 235/60/16 - White leather w/ blue cloth seats - white face gauges in 95 cluster
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post #5 of 17 (permalink) Old 01-08-2004, 05:24 PM
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if it were me, I'd get a 4.2 custom forged crank, forged rods and pistons from super six and rpm-mustangs, and make my own stroker kit.

Actually I plan on stroking my car to 4.1 or 4.2 using an sc forged crank and longer rods.

-Thomas

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post #6 of 17 (permalink) Old 01-08-2004, 06:02 PM
 
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You cant stroke an engine with longer rods. You'd have to change the actual stroke on the crank itself, Thomas. Having longer rods would only move the piston up in the cylinder, but the the difference between TDC and BDC(sic) would remain the same.
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post #7 of 17 (permalink) Old 01-08-2004, 10:06 PM
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I know, i believe there is something to do with regrinding the crank itself. I have to talk to rancherlee about it more.
-Thomas

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post #8 of 17 (permalink) Old 01-08-2004, 10:11 PM
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4.1L stroker using an 3.8L crank
3.58" stroke (252.7cid with a .060 overbore) and a 1.2" compression height = good

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post #9 of 17 (permalink) Old 01-09-2004, 08:46 AM
 
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i hope you werent thinking of adding boost... .060" over is quite a bit over. -greg
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post #10 of 17 (permalink) Old 01-09-2004, 03:17 PM
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it's been found that .060 over is very doable and safe amount. A friend of mine with a pretty decently modded 95 sc is getting a .060 overbore.
-Thomas

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post #11 of 17 (permalink) Old 01-09-2004, 04:25 PM
 
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*pulls head out of @$$*

wasnt thinking... yea .060" is very doable...


but what i dont get is: how is re-grinding the crank going to get you .18" more stroke?

i say unless you are putting an eaton on the motor, i'd do the .060" bore with a 4.2 crank (~263.30 cid). its probably easier to get a 4.2 crank and 99+ 3.8 oil pan and just swapping that in. i think itd be more worth it. eh, oh well. -greg
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post #12 of 17 (permalink) Old 01-09-2004, 05:09 PM
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I believe a new 4.2 crank from Ford is 300. I looked into it last summer and that is the number I remember hearing. You could contact Dan Newman to get a deffinate price.

it's hard to explain but imagine a large circle. Now imagine a smaller circle inside of that larger circle that has one point touching the outside edge. the center of that smaller circle is farther out than the center of the larger circle. The same principal is applied when regrinding a crank, thus giving it more stroke. Make any sense?

-Thomas

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post #13 of 17 (permalink) Old 01-09-2004, 05:53 PM
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Has anyone ever looked into doing a group purchase for a 4.2L forged, or billet crank? I would love to see one started, but I have no idea who to even talk to anymore about getting one made.

I hate it when you lose the folder of all your contacts for your bird......I think that the X has it somewhere, and if I know her.....it has probably either been used as a cage liner, or it was burned.

1997 LX Sport 4.6L 2.73 , MODS=SCT tuned/J-Mod/Trans Cooler/Dyno max Cat-Back/NgkPlugs/Mac cold air/March UD's/FRPP aluminumcarrier3.73's(spare for strip use)/ PI cams + PI intake manifold w/adapter plate/ Mark VIII Convertor/80mm L-Maf/70mm TB/ Mark VIII 1 piece shaft/Cobra R' wheels/ Kumhos 235/60/16 - White leather w/ blue cloth seats - white face gauges in 95 cluster
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post #14 of 17 (permalink) Old 01-09-2004, 06:05 PM
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Quote:
Originally posted by joshbea6
Has anyone ever looked into doing a group purchase for a 4.2L forged, or billet crank?
I don't think enough people would buy it. It would still be very expensive and I believe there just wouldn't be enough interest. But if there was I might just have to jump on in.
-Thomas

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post #15 of 17 (permalink) Old 01-09-2004, 07:46 PM
 
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Sorry I gotta jump in here .060 over on ANYTHING is just asking for core shift, bent parts, holed blocks and overheating not to mention a good way to start killing HG's and warping heads with abandon.
.040 MAX on an SC block!
The 4.2 crank on SOME of the early 4.2's was forged, I forget production numbers and VIN start/stop for them tho. (srry will get back with them tho)
One could offset grind a 3.8 crank to get some stroke at the expense of strength.
Honestly if the Eaton could be adapted to the split port heads that'd be a heck of a fun ride(Kenny Brown did this on his Winstars that may be a source for lower intake manifold help... imagine geting smoked by a mid 14 sec Minivan with duals and 13" discs up front).
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post #16 of 17 (permalink) Old 01-09-2004, 08:24 PM
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Jamie Hiscoe who has a mustang with a 90sc engine is working on making a split-port lower intake to do a split-port head swap.
-Thomas

1988 Notch Mustang: - 438W, direct port n2o, t56
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post #17 of 17 (permalink) Old 01-13-2004, 10:10 PM
 
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"....and the cylinder bores are widened by 0.030 inches (about the limit of the 3.8's thin-wall construction)........"

Muscle Mustangs & Fast Fords January 2003 Issue

Six Therapist Article page 188

This article is a story on Morana Racing and their work on stroking the 3.8.
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