How to: 4.2L mustang swap

[pete]

I have seen many questions...but few facts. This is what you need. I converted my 99 4 years ago.


Early 97-98 4.2s had a 2-pc main girdle that connected the 1st to the 2nd main cap and the 3rd to the 4th main cap and had larger main bolts. Mid-1998 and up 4.2s used a 1-pc girdle that only connected the rear 3 main caps and had smaller main bolts.

To use the early 4.2 in any Mustang will require replacing the girdle with a newer 3 main style from a 4.2, a 99-up 3.8 girdle or just delete it. You will also have to cut the girdle studs sticking out of the head of the main bolts on the 1st main bearing. The 99-00 3.8s used a factory windage tray/girdle that is better than nothing but certainly not ideal. The 01-up 3.8s use the same windage tray/girdle as the 4.2.

Late 00 3.8s are actually early 01 spec engines that are internally balanced. If you have one of these.....just use the notes for an 01-up.

Edit by 97Stallion: here's some extra info. 97-98 4.2L engine are directly compatible with 94-98 3.8 crank pulleys. So if you have a 97-98 4.2 crank and balancer, you can use your 3.8 crank pulley/underdrive pulley.


94-98 Single port heads

- 4.2 shortblock
- Single port heads/fuel rail/intake
- Mustang 3.8 water pump
- Auto trans = 4.2 or 01-up flexplate
- 5spd = 01-up or rebalanced 3.8 (0 or neutral) flywheel and a pilot bearing
- V6 Mustang bellhousing
- Re-use your stock cam position sensor
- 01-up 3.8 oil pan
- 01-up 3.8 oil pick-up tube and screen
- 4.2 damper or 01-up 3.8 damper (use the 01 pulley for blower cars)
- Re-use the stock 3.8 oil pressure sender and tube
- Re-use the Mustang headers
- You can use the 4.2 or 3.8 dipstick. Just keep track of where 5 qts puts the mark when refilling with oil.


94-98 Split port heads

*** You will need to perform all the mods required for a split port conversion plus these steps for the 4.2 (see pbmilan or V6sprout for the video) ***

- 4.2 shortblock or longblock
- You can use the 4.2 heads
- Mustang upper and lower intake
- Custom return style fuel rail (VMP has them)
- Mustang 3.8 water pump
- Auto trans = 4.2 or 01-up flexplate
- 5spd = 01-up or rebalanced 3.8 (0 or neutral) flywheel and a pilot bearing
- V6 Mustang bellhousing
- Re-use your stock cam position sensor
- 01-up 3.8 oil pan
- 01-up 3.8 oil pick-up tube and screen
- 4.2 damper or 01-up 3.8 damper (use the 01 pulley for blower cars)
- Re-use the stock 3.8 oil pressure sender and tube
- Re-use the Mustang headers
- You can use the 4.2 or 3.8 dipstick. Just keep track of where 5 qts puts the mark when refilling with oil.


99-00 split port heads

- 4.2 shortblock or longblock
- You can use the 4.2 heads
- Mustang upper and lower intake and fuel rail
- Mustang 3.8 water pump
- Auto trans = 4.2 or 01-up flexplate
- 5spd = 01-up or rebalanced 3.8 (0 or neutral) flywheel and a pilot bearing
- V6 Mustang bellhousing
- Re-use your stock cam position sensor
- 01-up 3.8 oil pan
- 01-up 3.8 oil pick-up tube and screen
- 4.2 damper or 01-up 3.8 damper (use the 01 pulley for blower cars)
- Re-use the stock 3.8 oil pressure sender and tube
- Re-use the Mustang headers
- You can use the 4.2 or 3.8 dipstick. Just keep track of where 5 qts puts the mark when refilling with oil.


01-up split port heads

- 4.2 shortblock or longblock
- You can use the 4.2 heads
- Mustang upper and lower intake and fuel rail
- Mustang 3.8 water pump
- Auto trans = your stock flexplate
- 5spd = your stock flywheel and a pilot bearing
- V6 Mustang bellhousing
- Re-use your stock cam position sensor
- Your 01-up 3.8 oil pan
- Your 01-up 3.8 oil pick-up tube and screen
- Your stock 01-up 3.8 damper
- Re-use the stock 3.8 oil pressure sender and tube
- Re-use the Mustang headers
- You can use the 4.2 or 3.8 dipstick. Just keep track of where 5 qts puts the mark when refilling with oil.

[Danger Dude]

Nice article there Pete. I am in the hunt for a 4.2 short block or 4.2 Crank, rods and pistons right now.

[STEVE]

this should be stickied, thats great information pete

[Brent]

wow! This is exactly what I needed to see

[jimmy_beaner]

agreed... may be asking you questions on exactly how to do it when I get closer to blowing up my engine

[plstktnkr2]

Your info is correct, but for the older mustang owners (83-86) some things need to be changed for the older(ie flat tappets or earlier roller) blocks (heads ,intakes ,flexplates ,dampers and such. ) not limited to crank and piston /rod combos

[chips]

Quote: Originally Posted by Danger Dude Nice article there Pete. I am in the hunt for a 4.2 short block or 4.2 Crank, rods and pistons right now.

check the classifieds at www.v6f150.com

i don't know if they have what you need, but it doesn't hurt to look.

[damarti2]

I have a 01 v6 mustang. About how much money is involved to swap it to 4.2?

[97Stallion]

Expect to pay close to $1500.

[fastmustangs1]

Where can I buy a 4.2 liter motor. I want to replace my 3.8 eventually.

Matt

[dark]

i'm gonna do this eventually. pete, stallion, my stang is a 1997. which version of the 4.2 would be the best to put in that year mustang? i want to make as much HP as i can off the engine before i put in the twin turbos. i'd like to go split port,and.. well, basically anything i can do to boost horsepower

can one of you 4.2 experts give me advice on this?

thanks

[97Stallion]

Well I think if you could choose a year, I would go with a 97 or a 98 for you. All the years are the same, but 97's and 98 have the same crankshaft pulleys as the mustangs, so if you have 97 4.2 crank and balancer, you can use your crank pulley from your mustang. It would just save you a few bucks.

[01mineralgrey6]

Quote: Originally Posted by Danger Dude Nice article there Pete. I am in the hunt for a 4.2 short block or 4.2 Crank, rods and pistons right now.

your not the only one

[plstktnkr2]

If you guys are hunting parts just go to advance auto parts and get a crank kit because 99/02 4.2's use same pistonsI believe. Rods are different I believe

[pete]

Quote: Originally Posted by 97Stallion Well I think if you could choose a year, I would go with a 97 or a 98 for you. All the years are the same, but 97's and 98 have the same crankshaft pulleys as the mustangs, so if you have 97 4.2 crank and balancer, you can use your crank pulley from your mustang. It would just save you a few bucks.

Yes, but if you are going to use a blower at some point go with the 01-up Mustang pulley/damper. Its the largest diameter.

[pete]

Quote: Originally Posted by plstktnkr2 If you guys are hunting parts just go to advance auto parts and get a crank kit because 99/02 4.2's use same pistonsI believe. Rods are different I believe

Other way around... Crank and pistons are different. The 4.2/3.8 use the same rods.

[98GreenStallion]

Im prolly just going to buy one of RPM's built street 4.2L shortblocks ($2290) when I have the money. then I will just swap my BV heads and intakes and get a new cam in prep for a S/C. By then ill have a new tranny and 8.8 rear as well.
This way I dont have to worry about the oil pan or flywheel or oil pick-up tube or anything, just simply swap engines!

[plstktnkr2]

This info is awesome for the guys with the later 3.8's . How about some luv for all of us guys with the 3.8 carb'd & CFI motors?
There were other 3.8's besides the SN94's

[RGR]

looking for 4.2 crank, rods and pistons

Quote: Originally Posted by 01mineralgrey6 your not the only one

Looking for 4.2 crank rods and pistons?

I have a set but the pistons are std. bore, however you could hone
the block and use them. It is not listed yet but the stuff will go in my
big Garage Sale cuz I gotta sell some stuff!


I'm telling you and not danger dog 'cuz I do not have the balancer and
you do not need it anyway... Sorry Corey Bro

[wiarumas]

what kind of numbers does the 4.2 push out? estimated horsepower and torque as well as quarter mile time?

[RGR]

250 RWHP is quite easy.

4.2's need porting all around, and the current goal is 300 RWHP
but those kind of #'s require really good combo matching, wild
porting to intakes and good headers (LT's) and a fine tune.
Might as well build a better shortblock while you're at it IMO,
but Justin @ 3.8 made 265 RWHP & 280 RWTQ with a stock shortblock.

[fastmustangs1]

I was thinking of swapping my 38 for a 42.

Matt

[Js281GT]

Strokers rule! Can't wait to purchase my 4.9 liter. What about a 5.4 stroked to a 6.0 RD should sell those shortblocks.

[RGR]

Quote: Originally Posted by fastmustangs1 I was thinking of swapping my 3.8 for a 4.2. Matt

What year? I have a cheap crank and pistons FS.
96 and up re-use their rods. LMK!

[donnie]

how much hp gain you'll get after doing this and how much money will cost me for this parts and labor?

[Danger Dude]

Not so much HP but torque. You are at 4.6 Gt torque

[PCD]

OK, if any of you guys have the cash, Litning at TCCoA.com, has a 4.2 that he was building for his T-Bird. The engine is for sale. It is tricked out with powder coated parts. He lives up in New England.

You want a 4.2. Here's one more than ready to go into your stangs.

[plstktnkr2]

Hey RGR the franken motor runs baby and sounds kick-butt with open headers in a carport at 10pm!!! woke up my neigbor (but he has a loud "bubba truck" so I didn't mind lol