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Best block to start with?

3K views 14 replies 8 participants last post by  Tbird1997 
#1 · (Edited)
I am still in my planning stages of my 4.2 build/swap. I have done a good bit of reading and searching and reading. It has gotten time to make some decisions on a few things, and I need a little guidance.

I have multiple splitport engines to choose from. There are 4.2L F-150s, 3.8L Windstars, and 3.8L Mustangs all of multiple years I have access to. I originally was thinking of grabbing a 2004 4.2L short block, and the entire engine/trans/harnesses/etc from a 2000 Mustang. Then using the top end from the Mustang on the truck block and the Windstar upper. I don't see much issue with that all working out. I would keep the Mustang trans as a spare.

On another note, last night I was thinking about using an SC short block. From what I have read, the blocks are the same - 3.8 n/a, 3.8 SC, and 4.2 n/a. That being said, the 4.2 difference was that the pistons were different (wrist pin is higher) and the crankshaft was different (iirc). The question here is should I use an SC short block and gain the forged internals, and just buy new/used pistons and a new/used crank (if necessary?)

With the wealth of these engines in my junkyard and the relative ease of interchangeability, I want to use the best factory parts I can. I don't want a power monster, but I figured while I was doing it I might as well use the best of what is available. I have been studying a lot of builds on these engines, but I'm not as sharp as some of you guys with more experience. Any insight or opinions are welcomed. Any suggestions are encouraged. Thanks
 
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#4 ·
From what I've seen I believe a 01+ Mustang 3.8 is on par with a SC.

Almost nothing from a SC will interchange with any other block--not worth the hassles.

If no Boost and you want stroke get the 4.2 that way you get the Ford crank, which is no longer available from Ford.

For the internals SC got forged crank and Rods that's it and guys running 4.2 cranks in SC are having no problems. If you run a SC crank you must run SC mains, #4 journal is different .010 under.

Now 96+ heads are equivalent to SC but slightly different but I assume you would do a Split port.

IF you do go with a SC block you will need a 94/95 for the crank sensor provisions.
 
#5 · (Edited)
Well, I would be running whatever block with the original 94 EEC and harness (modified). That should eliminate any extra sensors past what the factory 94 3.8L had. More good info on that SC stuff. I will go with the original plan of the '04 4.2 then. As for heads, yes I would be using the '00 Mustang heads and lower intake.

Edit: I was also wondering if it would be worth the hassle of keeping the EGR. I've read that you gain a couple MPG with it, but it will be a PITA with this swap. I am willing to do the work though, if that is the better way. I have to get a tune anyways, so deleting it could be written in.
 
#6 ·
The 4.2L would allow you to re-use your existing exhaust and engine mounts. My plan for the lemons car is to go that route as soon as I can find an affordable block. I'm using my 95 3.8L harness (with some connectors swapped in/extended) and ECU for my splitport already. While others have kept EGR, I would hate to do so as well...
-g
 
#7 ·
Ok, I did some recon work this weekend. I found that the '04 4.2 block I was looking at may be too far gone to save (easily). Someone has pulled the passenger head and those 3 cylinders/pistons are pretty rusted. There are 2 '99 and a '98 4.2 out there that are complete.

Here is a shot of the damage:



On another note, I did some tinkering with fuel rails. For those that have done this swap, do any of these look like they would pose a problem? (Note: These pictures are on a '04 4.2 block/intake. I'm not sure of the differences between the 4.2 and the 3.8 lowers - if any)

This is the factory '04 4.2 rail turned 180*:

Passenger side (head is gone, injectors seem to line up ok):

Driver side:


This is a '97 3.8 Windstar rail:

Room for dizzy and EGR??

Passenger side:

Driver side:


This is a side-by-side of the above 2 rails. 3.8 Windstar on the left, 4.2 on the right:
 
#8 ·
The issues with those rails is that they don't clear the stock 99+ mustang intake. I have no idea if they clear the Windstar intake though. If i was you, I would pull a dizzy out of a tbird and find a upper intake and mock it all up while at the yard. The dizzy comes up higher than you would think.

 
#9 ·
If you see my DIY, I ended up using (2) halves of a Mustang splitport fuel rail plus the portion of my 95 fuel rail that held the FP regulator. Of the mustang rails, I used two of the segments that on a stock mustang would be from the driver's side.

If you do decide to use the passenger side segment from the rail, you will need to tweak it as by default, it will want to be about 1/2" into the area occupied by the distributor cap. Using the driver's side fuel rail segment on the passenger side alleviates this issue.

I could have gotten away with just cutting/tweaking a single Mustang splitport rail BUT for a small incremental cost (the cost of a second Mustang fuel rail), I ended up having ZERO DIY connections (didn't JB Weld + Braize any connectors onto the rails). I just used the stock barbs.

If you have the patience, I'd wait for another V6 F150 engine and snap it up. If you are looking for the "ultimate" setup, you can pick up a Windstar upper Intake but performance wise, it's pretty much the same as an F150 upper intake but cast out of plastic vs metal.

V6 F150s are probably more common in your part of the country than CA (where anyone who has a truck probably really needs it so it is more likely to be a V8 than a V6).

-g

PS. I'm pretty sure you will need to relocate the EGR if you go with the F150 or Windstar intakes. There's simply not enough room up front with the Throttle Body, the Distributor, and the cooling hoses.

 
#10 ·
Yeah relocate the EGR into the trash.
 
#11 · (Edited)
I've read your thread at least 5 times lol (and saved it as a .pdf). I am trying to find a factory rail that I can use without modding. I haven't seen anyone use the Windstar rail so I thought I would put it on there. It looks like it gives a good bit of room for the distributor, but looking at it again that 'u-turn' might stick out too far.

There are at least 3 other 4.2 trucks out there. There is also a 98 splitport mustang. I took pictures of all of them for reference on how each was setup. They are very similar. I will probably end up grabbing one of the '99 4.2 short blocks. Just as soon as I find another set of hands and a day off :rolleyes:

FWIW, I already have the Windstar upper. I got it a few weeks back. That's another reason I played with the Windstar fuel rail because it was easy to get to. I plan to get the VAP angled TB plate and relocate the IAC. I was going to ask for advice on what TB to use, and what MAF would be a good upgrade while I was having a tune made. I still haven't decided on the EGR.

EDIT: I did pull a distributor to mock it all up, but I ran out of time. Maybe I will do that while I am pulling the top off of the 4.2.
 
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