Hey guys names Axel. I've been doing a lot of research into building my mustang, a 3.8L 2000 Mustang, into a 4.3L stroker on a budget. From what I've read the best way to approach this is by dropping the crankshaft, pistons, and flywheel from a 1998 4.2L Ford F-150 into my 3.8L. What challenges do you think I can face if I go ahead with this project. My biggest concern is whether or not I need to take the motor to be balanced because the 3.8L is internally balanced while the 4.2L is externally balanced. Thanks in advance for any help.
From what you're asking, if these are your questions then you should wait on the project until you do quite a bit more research. There are plenty of threads on 3.8L-stroker builds. My first recommendation would be research your 3.8L first, then and only then start looking into a stroker build.
There's literally entire builds with the part lists in the stickies that tell you what you need for the stroker build as well as all the info you'd every need on your car without stroking.
Also you're 3.8L has about a 50-50 chance of being internally balanced vs externally balanced. The 2000's where the switchover year where they changed from externally balanced to internally balanced. So easiest method for you to determine this is to simply look at your harmonic balancer to determine which you have.
Just find a whole 4.2L truck engine and build that. Drop it in after.
Mine's a 2000 and is externally balanced. Mine was bought in 1999. Check for a crankshaft pulley on the outside. If it's not there it's internally balanced.
Ummm...., The crankshaft pulley should be there regardless of whether or not it's internally or externally balanced. The difference is in the design of the crankshaft pulley itself no the existence of the pulley.
If the pulley is symmetrical all the way around then it is internally balanced, if it has a lump of addition mass (extra weight) on it then it's externally balanced.
Basically the easiest is to pick whether you want to keep both the flywheel and the crankshaft pulley from the old engine or the new engine. Regardless, if you keep the pair from 1 engine or the other then the balance being internal versus external should be mute.
What exactly are you looking to do in the long run? Since you said your trying to do this on a budget I'm assuming you won't be using forged internals. Winnie already answered your balancing question but if your just going to drop a 3.74" stroke crankshaft with new 4.2L pistons for proper compression ratio, then it would be a 4.2L stroker. The 4.3L strokers get there extra tenth liter of displacement from 0.030" overbore pistons. If you just want a 4.2L stroker without forged parts, it may be easier to swap a F150 4.2L in, however I understand wanting to build your own engine; I personally never trust junkyard motors if I don't know their history and I have a reliable engine ready to go. At the very least I'd want to rebuild the junkyard motor with new seals and gaskets but if your looking for the lowest cost possible a straight swap without rebuild might be the way to go. I'm sure your aware of super six motorsports by now, but just in case they offer 4.2L or 4.3L strokers with forged internals. You can also buy the connecting rods and pistons separately if you just want new pistons. They will balance the rotating assembly for $275 if you need it.
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