[winnie51189]

It's been a long time since I've been on here, sadly. But I've finally gotten some free time and some parts for getting my mustang back on the road. I'll try and get pics loaded later.

Basically the old (2000) 3.8 chipped a piston and that was that.
So I got a bare 4.2L block from a 97 f-150 and an engine overhaul kit for it as well. So it's time to build the new engine. However before blowing another 250ish on new connecting rods, I'd like to know if the ones out of the old 3.8 are the same so I can reuse them and put the saved money towards something else like a Tubular K-member .

I have a few other things to pick up like a girdle, windage tray, and 01+ crank pulley so if anyone has anything I might need for sale let me know.

[walt1120]

Hmm i thought 3.8/4.2 rods are the same length. id also like to know if they are different

[6ixer]

Only diff tht I know of a 3.8/4.2 is tht

Same bore .........
The upper intake looked like a varient of a windstar upper...
But anyway.....
The only diff I know is tht the crank shaft kis "+igger" or w/e because it has a longer stroke

[2000stallion]

Finally! a 4.2 build thread. Please take a shit load of pictures and do a good write up. Ive been waiting on this! Good luck as well.

[JTs03v6]

The 4.2 uses different crank, rods, and pistons.

[southfour!]

not sure if its a good price but $250 shipped for a girdle

Delk Performance Main Girdle and ARP Studs

[winnie51189]

everywhere I've looked has said the rods are the same, but pistons and crank are different. My new pistons and crank are waiting to be put in except rods. I just don't have the measurements on the stock rods to see if they are the same or not.

[southfour!]

here is the list of things i compiled from various 4.2 threads on 3.8mustang.com and v6p.net

i did not write any of this***



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, get 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.


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
- 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
- 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
- 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
- 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 stcok 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.



The 99-04 lowers are essentially the same (with difference with IMRC's). The only difference is it will require additional modification of coolant lines. A 3.8 lower will make the swap more streamline.

99-04 3.8 heads and 4.2 heads are the same.

It's actually has to be the same engine from the same model year vehicle or newer, not older.

A 4.2 with Mustang intakes does not look any different from a 3.8. Externally it's the same thing.

The engine balance isn't dependent upon the block, but rather the crankshaft. Since all 4.2 crankshafts are internally balanced, you cannot reuse your external balance harmonic balancer even if you reuse your 3.8 engine block. You will also need to use the correct flywheel/flexplate.

The 4.2 pistons are different than the 3.8 pistons. The rods are the same length.

Don't get your flywheel rebalanced, rather, replace it with an external balance one. A used flywheel is fine if you get it resurfaced. Spec also makes a steel flywheel for these engines.

The write up is about using a truck block. So if you use a block from a truck then you will need to get the 01 Mustang pan and pick up to clear the parts you mentioned. If you build the 4.2 using your 2000 3.8 Mustang block then you can reuse your 2000 Mustang oil pan and pickup.

The girdle strengthens the short block , if you plan on your engine making over 450RWHP I would use a girdle.
For 99-00 It is very important that you change your flywheel to an 01+ flywheel though! If you do not, in the short term you will have annoying vibration which will quickly turn into serious engine damage.

if you plant to make no additional modifications and your budget is $600 then you'd probably end up better off getting a used 4.2 truck engine

Yes there is a difference, they will produce different sounds! The 4.2 cam will sound a little more choppier than the 3.8 cam as it is a little more aggressive. Old posts on v6p said the 4.2 cam sounded better than the stock cam in a 3.8. I would be willing to bet that the 3.8 cam would sound weak in a 4.2 using the compairson.

The 2 cam specs are as follows:

99-up 3.8L
.423/.447 246/262 116 LCA 26 deg overlap

97-up 4.2L
.424/.447 252/270 110 LCA 32 deg overlap


I did some other modeling using the 4.2 cam in a 3.8L = some nice gains. About 5 ft/lbs of torque all through the mid-range and at least 12 HP. Thats a pretty good gain that could get you a couple of tenths in the 1/4 for no $$$. Some of these guys building 4.2s have the stock cams leftover...could be a real cheap alternative to a custom cam

Some people have said the truck pan clear the Mustang K-member while other people have had it interfere, while no one has had a problem with the 2001+ Mustang pan clearing the Mustang K-member.

[stephen]

Originally Posted by winnie51189 everywhere I've looked has said the rods are the same, but pistons and crank are different. My new pistons and crank are waiting to be put in except rods. I just don't have the measurements on the stock rods to see if they are the same or not.

Because of the longer stroke in the same block some of the geometry has to be different. I believe the same (3.8) rods can be used with a different piston that has the piston pin shifted to compensate for the longer stroke.

[GOLDSTANG]

would you need the trucks transmission for this, or will the mustangs work for it, auto transmission in my case. If you do this please post pictures and details.

[ESG-642T]

Originally Posted by GOLDSTANG would you need the trucks transmission for this, or will the mustangs work for it, auto transmission in my case. If you do this please post pictures and details.

Nope mustang trans. The simplest way to do this is just get a complete short block.

[winnie51189]

Well thats all good news. Now I can get that tubular K

[winnie51189]

Got some bad news and good news. Bad new: My dad lost his job (and the company vehicle) mid Dec, but has secured a couple interviews at various places, so now my dad needs the jeep which has been my DD while the car has been out of commission. Which means my car has to be back up and running ASAP with school starting just around the corner.

Since my dad is commandeering the jeep he's trying to place a salvaged 3.8 to throw in the mustang by this weekend. This means my 4.2 has been delayed. But on the bright side that means I'm going to be sinking more money into the 4.2 build so once I get a chance to drop the 4.2 in it'll be one lil monster on the streets.

[mustangmike!]

how's this going for ya ?

[winnie51189]

Going well, just slow. I've got 18 credit hours this semester for Mechanical Engineering and I'm in charge of a lot of stuff on the Formula SAE car this semester as well. Not leaving me much time for myself. But it's slowly coming along.

[mustangmike!]

I hear ya there, ill let you know how mine goes

[mustangmike!]

Originally Posted by southfour here is the list of things i compiled from various 4.2 threads on 3.8mustang.com and v6p.net i did not write any of this*** 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, get 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. 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 - 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 - 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 - 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 - 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 stcok 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. The 99-04 lowers are essentially the same (with difference with IMRC's). The only difference is it will require additional modification of coolant lines. A 3.8 lower will make the swap more streamline. 99-04 3.8 heads and 4.2 heads are the same. It's actually has to be the same engine from the same model year vehicle or newer, not older. A 4.2 with Mustang intakes does not look any different from a 3.8. Externally it's the same thing. The engine balance isn't dependent upon the block, but rather the crankshaft. Since all 4.2 crankshafts are internally balanced, you cannot reuse your external balance harmonic balancer even if you reuse your 3.8 engine block. You will also need to use the correct flywheel/flexplate. The 4.2 pistons are different than the 3.8 pistons. The rods are the same length. Don't get your flywheel rebalanced, rather, replace it with an external balance one. A used flywheel is fine if you get it resurfaced. Spec also makes a steel flywheel for these engines. The write up is about using a truck block. So if you use a block from a truck then you will need to get the 01 Mustang pan and pick up to clear the parts you mentioned. If you build the 4.2 using your 2000 3.8 Mustang block then you can reuse your 2000 Mustang oil pan and pickup. The girdle strengthens the short block , if you plan on your engine making over 450RWHP I would use a girdle. For 99-00 It is very important that you change your flywheel to an 01+ flywheel though! If you do not, in the short term you will have annoying vibration which will quickly turn into serious engine damage. if you plant to make no additional modifications and your budget is $600 then you'd probably end up better off getting a used 4.2 truck engine Yes there is a difference, they will produce different sounds! The 4.2 cam will sound a little more choppier than the 3.8 cam as it is a little more aggressive. Old posts on v6p said the 4.2 cam sounded better than the stock cam in a 3.8. I would be willing to bet that the 3.8 cam would sound weak in a 4.2 using the compairson. The 2 cam specs are as follows: 99-up 3.8L .423/.447 246/262 116 LCA 26 deg overlap 97-up 4.2L .424/.447 252/270 110 LCA 32 deg overlap I did some other modeling using the 4.2 cam in a 3.8L = some nice gains. About 5 ft/lbs of torque all through the mid-range and at least 12 HP. Thats a pretty good gain that could get you a couple of tenths in the 1/4 for no $$$. Some of these guys building 4.2s have the stock cams leftover...could be a real cheap alternative to a custom cam Some people have said the truck pan clear the Mustang K-member while other people have had it interfere, while no one has had a problem with the 2001+ Mustang pan clearing the Mustang K-member.

Do you HAVE to switch over the oil pick up ??? It looks exactly the same IMO ?

[southfour!]

Originally Posted by mustangmike! Do you HAVE to switch over the oil pick up ??? It looks exactly the same IMO ?

i have no idea, i just read the "official" 4.2 swap thread on v6p and took notes of what i thought i would need to remember, which you see above. lol

[Mr. Red Pony]

Originally Posted by ESG-642T Nope mustang trans. The simplest way to do this is just get a complete short block.

Amen. I might be doing that soon.

[dark_horse]

i plan on doing a 4.2 build at some point but im still confused and i have a few qurestions

1) sorry for bringing this tread up again lol


2) from my understanding my best bet would get an 01-04 motor and get the 4.2 block and swap all i can onto the 4.2 rite?...i just want to make sure so i get all i need and not need something later lol...i have a 2000 and noticed it would be easier to get an 01-04 motor

3) a do i need 4.2 pistons and connectors???

4) i have an external balancer, and i have an 25% ASP UP. i know the pulley can come off the balancer on UP...but does anyone know if i can take and internal balancer and take it pulley off and the the under drive pulley on it?

5) i would like to put in a better cam, i love the sound of the lumpy...but at some point or another i would like to run some spray, what would be the best cam to run with, and also get a good sound of the cam?

im hopeing to get around to start this build in june/july...im just wanting to get around and start collecting things