Welcome To V6Mustang.com!

We are the oldest and largest V6 Mustang forum on the internet. If you have any questions about your V6 Mustang or just want to connect with other V6 Mustang owners around the world, you have found the best place on the internet to do that.

Registering is free and easy! Hope to see you on the forums soon!

4.2L Stroker Build

Discussion in 'Personal Projects and Builds' started by mythorath, Oct 21, 2017.

  1. mythorath

    mythorath New Member

    Joined:
    Oct 21, 2017
    Messages:
    3
    Likes Received:
    1
    Trophy Points:
    3
    Hello all, here’s the current state of my 02 mustang build.

    Non- engine stuff is quick and simple. Everything is stock except the following: Suspension (upgraded shocks / struts, lowered 1”, added rear sway bar), Automatic transmission (modified valve body), Gas pedal modded, and that about it for non-engine related stuff.



    The engine is the current project. It’s a stock Ford 3.8L Essex V6. It’s currently out of the car on an engine stand, completely torn down. Found a bit of bearing damage in the engine. All of the rod bearings on the passenger side of the car were semi pitted / scored. I'm thinking the pitting came from dumping coolant in the engine and letting it sit for a month before finishing the tear down. (can coolant do that to a bearing?) I added a pic of the worst bearing, that happens to be missing a chunk as well, next to one of the better looking bearings.

    20171021_163331.jpg



    The plan is to stroke it to 4.2L and do whatever else I can think of / afford. So far the only things that’s really been done to the engine is I polished the lower intake runners.

    While I would love to do the entire engine at once, I’ll be splitting it into two stages: Bottom end, and top end. The bottom end is what I’m working on first. This includes everything below the heads. Most of the top end stuff will happen after the engine is back in the car. I know I’ll need to get the engine back in the car before I can finish everything, so I plan for 2 stages, but hope for 1.



    I need a bit of advice on a few things:

    Camshaft:

    218 at .050 Intake, 226 at .050 Exhaust, 112 lobe separation

    https://www.summitracing.com/parts/cca-44-704-9/overview/make/ford

    Think this would be a good cam? Too big, too small? I’m not very knowledgeable when it comes to cams.

    Pistons / Cylinder bore:

    I have no idea what to get. I figure it might be good to get it bored, even a little, to eliminate any sort of ridge that may have formed in the bottom section of the cylinder. I don’t know if this matters, or if the ridge at the bottom is even a thing that happens, but doesn’t the piston go further down into the cylinder when it’s stroked to 4.2? Just don’t want to murder my rings right off the bat.

    I’m thinking about over-boring 0.020” – 0.030”, then throwing in some semi cheap hypereutectic pistons from summit. Again, I don’t know if it’s worth it though.

    4.2L stroking:

    I’m not 100% sure what all I need to make this work. I know I need the crank, don’t know about other parts. I’ve heard 2 different things on this, and can’t seem to find a solid answer.

    Path 1: just change crank, and harmonic balancer and reuse everything else.

    Path 2: change crank, con rods, pistons, harmonic balancer, flex plate (for auto), and remove windage tray.

    Honestly just kind of making it all up as I go at this point, until someone can offer some sound advice.

    I added some random pics but don't really know what to show. anyone want to see anything specific? it's just a bunch of parts right now.

    Comments, questions, concerns, advice, and criticisms are always welcome.





    List of parts I have:

    4.2L crankshaft

    (wow such a long list…)





    Parts I still need:

    Pistons

    Camshaft

    Gaskets / seals

    Bearings

    Harmonic balancer

    Timing chain tensioner

    Tuner

    Valve Springs

    Push rods

    Lifters

    Lots of machine shop work

    More will be added as I remember


    20171021_163346.jpg 20171021_163356.jpg 20171021_163404.jpg 20171021_163407.jpg 20171021_163410.jpg
     
    Lonnie-S likes this.
  2. The_Red_Stig

    The_Red_Stig New Member

    Joined:
    Oct 22, 2017
    Messages:
    3
    Likes Received:
    2
    Trophy Points:
    3
    4.2/3.8 connecting rods are the same so you may be able to reuse yours or just get factory replacements. You will need 4.2 pistons and matching rings as they are not the same as 3.8 pistons, 3.8 pistons may work, but your compression ratio will be off. Also, i don't know if summitracing is selling the hypereutectic pistons as an upgrade, but the factory pistons are already hypereutectic and are actually fairly robust up until around the 400 hp range. Over boring 0.030" would actually give you a 4.3L stroker, don't over bore more than that, you'll risk weakening the block too much. The cast factory connecting rods are really the weak link in these engines. They don't handle revs well, 5500-6000 rpms is really their reliable limit. Beyond that, and the big end of the rods will oval out over time. So that being said, that camshaft you have listed is really too aggressive for an engine without ported heads and intake manifolds. Its powerband (up to 6200 rpms) is beyond what you could safely run without forged rods. The 44-702-9 cam is probably a good option. You will need upgraded beehive valve springs with that cam, part#: 26918. That's all you have to upgrade valvetrain wise but roller rocker arms and hardened pushrods are always a good idea too. This link below should help you out.

    V6 Stroker Build - Muscle Mustangs & Fast Fords
     
    mythorath likes this.
  3. 6 Shooter

    6 Shooter Well-Known Member

    Joined:
    Jan 4, 2013
    Messages:
    1,284
    Likes Received:
    205
    Trophy Points:
    73
    Location:
    Dallas, TX
    3.8 pistons will not work with a 4.2L crank. The 3.8 piston skirts will be too long and smash into the crank counter weights. So, if going with a 4.2 crank, you will need pistons with shorter skirts. Suggest you get a hold of Tom at Super 6 motor sports who has and can get Comp to make off-set forged pistons for the 4.2L crank that correct for the geometry of the longer stroke of the crank. The pistons can or cannot come with the piston rings. And, if you decide to bore out, you should FIRST get the pistons in hand and have the bore cut then honed afterword to perfectly fit to the purchased pistons.
     
    mythorath and CrzyMunk like this.
  4. mythorath

    mythorath New Member

    Joined:
    Oct 21, 2017
    Messages:
    3
    Likes Received:
    1
    Trophy Points:
    3
    Okie dokie, thanks for the advice so far.

    This week I will be ordering more parts, I want to get my pistons before sending the block off to the machine shop. I'll check with SuperSix on pistons before I make any purchases.

    The question I have now is: What kind of difference is there between the custom pistons that super six can get, and normal 4.2L pistons from summit? Would it run different?

    side question: how much power can a stock 7.5" rear end take? I've blown two up on stock power, but just curious how much other people have managed. (I'll be upgrading it soon after engine is done.)
     
  5. 6 Shooter

    6 Shooter Well-Known Member

    Joined:
    Jan 4, 2013
    Messages:
    1,284
    Likes Received:
    205
    Trophy Points:
    73
    Location:
    Dallas, TX
    Call Tom at Super 6 and ask him to explain the 4.2L offset pistons. He is the best source for info and parts.

    On the 7.5 rear, it is easier to tear one up with a stick while reving the motor and dumping the clutch.
     
    mythorath likes this.