The official 4.2 swap post

[pete]

I can't remember there ever being a truly accurate 4.2 post so here goes...


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.


I am sure there is something I am forgetting... I will update this as required.

[Bloodninja]

Nice, thanks Pete. After this kicks around for a while it needs to head straight
for the tech archives.

[justin00v6]

Very good.

Some Prices from the dealer:
Zero Balance 01+ 3.8 Flexplate runs ~$35
01+ 3.8 Oil pan is ~$90

I believe 97-98 4.2s have a 2 piece balancer/crank pulley, just like the 94-98 3.8 stangs. With that year balancer you can just bolt on a 94-98 3.8 UD pulley.

For 99+ 4.2s which have a 1 piece balancer/pulley you'll need to buy an ASP UD pulley for a 01+ 3.8 mustang, that includes a zero balance balancer and UD pulley.

You can kind of reuse the header gaskets, they are SS. The valve cover gaskets are reuseable. The paper upper to lower intake gasket can be reused if its not torn but they often get torn. The lower intake to head gaskets look like they can be reused but its best to buy new for something critical like that.

[V6Sprout]

good info Pete.

Whats the difference in oil pans from a 94-00 stang and a 01+ stang pan? I notice you say you need the 01+ oil pan. Didn't know there was a difference.

This should be put in the tech archives.

Pete see if you can get some pics for this as well showing differences and why parts are needed.

[Justang2k]

what about the timing cover? are they the same? I already have the gasket for the 3.8 timing cover gasket already. will it work? what about the front main seal? same situation.

[Talleywacker]

Very nice post Pete. Definately tech material...

...too bad I came 4.2 woot!

[pete]

Timing cover is the same for 4.2 and 3.8.

The 01 pan has a couple of bumps to clear the No.2 main girdle and bolts. The 94-00 pan will not clear either of the 4.2 girdles.

I always replace the intake gaskets....just not worth the risk of a vac leak.

I always use the factory exhaust manifold gaskets. They never leak.

When installing the timing cover....don't skimp on RTV and take your time. I usually smear a thin coat on both sides of the gasket to insure a leak-free install. If the cover leaks you can end up with coolant into the oil and vice versa.

[RGR]

Kewl, Jose and I will use this for his conversion

Very complete, listing all years/head styles!

[Justang2k]

01 Flywheel $167.45
01 Pilot Bearing $11.17
01 Oil Pan $84.88
01 Oil pick up tube and screen $14.35

----------------------------------------------------------------

Justin made a reference to the 01 flexplate being $35. do we need the new flexplate? or just the flywheel?

---------------------------------------------------------------

Also, the engine I'm getting is a 98. Do I just keep the stock 4.2 balancer on it? I have the ASP UDP on my car right now. could I just use the pulley on the stock 4.2 pulley? the UDP is a two piece.

[Talleywacker]

Originally Posted by Justang2k

01 Flywheel $167.45

Do I just keep the stock 4.2 balancer on it?

Keep the 4.2 balancer and just bolt on the ASP Pulley to it.

For Reference:

02 4.2 Flywheel = $77.64 alot cheaper

[justin00v6]

Originally Posted by Talleywacker

Keep the 4.2 balancer and just bolt on the ASP Pulley to it.

Won't work. 94-98 stangs and 97-98 4.2s use a 4 bolt balancer. 99+ stangs use a 3 bolt balancer.

[Justang2k]

but the 02 4.2 flywheel will work?

[Talleywacker]

Originally Posted by justin00v6

Won't work. 94-98 stangs and 97-98 4.2s use a 4 bolt balancer. 99+ stangs use a 3 bolt balancer.

doh... for some reason I thought he had a 98 and was putting in a 98 4.2... stupid me

[SteveC]

Originally Posted by Justang2k

but the 02 4.2 flywheel will work?

Yeah it will work.

[Justang2k]

cool. that saves me some money.

what about the flexplate? do I need a new one? Justin mentioned those, so I was just wondering.

[SteveC]

Flexplate= auto
Flywheel= 5-speed

[justin00v6]

I'm wondering if the 5spd 4.2 flywheel could be different, they use an 11" clutch too? but with a different tranny?

[pete]

Originally Posted by justin00v6

I'm wondering if the 5spd 4.2 flywheel could be different, they use an 11" clutch too? but with a different tranny?

I looked at this before.... I could have sworn the holes were different from 4.2 clutch to 3.8 clutch.....meaning they wouldn't bolt up with out redrilling the 4.2 flywheel. I thought there was also a slight diff in thickness.

[Phantom GT]

are there any pics of what this swap looks like?

-

[Lunchbox]

Originally Posted by Phantom GT

are there any pics of what this swap looks like?

-

If there was one picture that would sum up an engine
swap, I would like to see what it is. haha

[pete]

The 4.2 is identical to the 3.8 on the outside. No need for pics.

[Boozshey]

Great posts. I have been searching for something like this for a very long time. Since I read about that Kenny Brown 4.2L. Anyways, my problem is I don't have a local source for blocks and my internet searches have left me dry. Anyone know where I can get my hands on a 4.2L Block, ONLINE!!! Or someone that might be willing to crate ship it internationally? I know someone who just sent a 5.0L engine over here to Germany and it was only $200.00 to ship. I would be willing to pay for it. Please help!!!

Oh and I just wanted to let everyone know I smoked a BMW 525 Euro specs on the Autobahn today. Well at least until my stupid govenor kicked in. GO STANGS!!!!

[Justang2k]

Originally Posted by Boozshey

Great posts. I have been searching for something like this for a very long time. Since I read about that Kenny Brown 4.2L. Anyways, my problem is I don't have a local source for blocks and my internet searches have left me dry. Anyone know where I can get my hands on a 4.2L Block, ONLINE!!! Or someone that might be willing to crate ship it internationally? I know someone who just sent a 5.0L engine over here to Germany and it was only $200.00 to ship. I would be willing to pay for it. Please help!!!

Oh and I just wanted to let everyone know I smoked a BMW 525 Euro specs on the Autobahn today. Well at least until my stupid govenor kicked in. GO STANGS!!!!

did you try:
www.stangparts.com

or maybe here:
http://www.midwestmustang.net/

[justin00v6]

Originally Posted by Boozshey

Great posts. I have been searching for something like this for a very long time. Since I read about that Kenny Brown 4.2L. Anyways, my problem is I don't have a local source for blocks and my internet searches have left me dry. Anyone know where I can get my hands on a 4.2L Block, ONLINE!!! Or someone that might be willing to crate ship it internationally? I know someone who just sent a 5.0L engine over here to Germany and it was only $200.00 to ship. I would be willing to pay for it. Please help!!!

Oh and I just wanted to let everyone know I smoked a BMW 525 Euro specs on the Autobahn today. Well at least until my stupid govenor kicked in. GO STANGS!!!!

I have a 4.2 crank here...only weighs 40lbs, so you could pick up a 3.8l locally maybe to put it in...or I could send you the block and everything. justinv6@bellsouth.net

[MNeofreek]

I know that you guys said that the 3.8 water pump is the one to use...but will the 4.2 water pump work if I were to use the 4.2 timing cover? For some reason my 94 3.8 waterpump wont bolt up to the 4.2 shortblock. Its either try the 4.2 pump, or replace the timing cover and oil pump to make the 3.8 water pump work.

[pete]

It would be tough to use the 4.2 pump. Its meant for a pump mounted cooling fan.

[Suprman]

Originally Posted by MNeofreek

I know that you guys said that the 3.8 water pump is the one to use...but will the 4.2 water pump work if I were to use the 4.2 timing cover? For some reason my 94 3.8 waterpump wont bolt up to the 4.2 shortblock. Its either try the 4.2 pump, or replace the timing cover and oil pump to make the 3.8 water pump work.

you know what i believe for made a water bump change from 94-95 to 96-98 because when i tried to put my stock 95 pulley on the new 97 engine the hole wasn't big enough! but luckily i had an underdrive pully that was too big for the 95 and it fit perfect!

[MNeofreek]

Could I be using the wrong year of waterpump? I tried using my 94 and it didn't bolt up. Did they really make any changes in 96 or 99? What year waterpump did you guys use and which timing cover?

[PJ-4.2L]

Originally Posted by pete

It would be tough to use the 4.2 pump. Its meant for a pump mounted cooling fan.

I've been running a 4.2L pump and timing cover for some time now. No probs here.

PJ

[pete]

There isn't any issue running the timing cover. The 3.8 and 4.2 use the same cover.

The 4.2 water pump has a larger snout on the end for the fan. All 3.8 water pump pulleys will not fit it (hole too small in pulley).

[Justang2k]

Will the 4.2 Upper work on the 3.8 lower? does it give any advantages?
Clearance issues with the hood?

and refering to the mid98's having a once piece girdle, this would be the one piece wouldn't it?


[/img]

[Bloodninja]

Originally Posted by Justang2k

Will the 4.2 Upper work on the 3.8 lower? does it give any advantages?
Clearance issues with the hood?

While it would probably help the low end that you said you're looking for but
hurt you on the high end, it won't fit even with a cowl hood, so you can't use
it without serious modification.

[justin00v6]

mid 97 and earlier 4.2s have a main girdle that ties in all four main caps, later 4.2s have a girdle that only ties in the rear three

you have the later girdle justang

[SMoKEDya95stang]

What are the exact parts and ect i need to do to transfer this 3.8 block to 4.2?

Crank and rods?

what else?

[Justang2k]

ran into a little dilemma. On the 4.2L block there is a sensor on the passenger side of the block. But on my 3.8 there is a plug where that sensor is. should I just use the plug where that sensor is? If I don't remove that sensor, I can't use my 3.8 motor mounts. it's right in the way.

what is that sensor? it seems to be an extra. I have all my other sensors installed.

[justin00v6]

its a knock sensor, your 3.8 doesn't have one

[Justang2k]

Originally Posted by pete

- Re-use the stock 3.8 oil pressure sender and tube

yes, you must use the tube. I didn't catch that. when I went to put the Alt/PS pump bracket on, it wouldn't fit. the tube is about an inch longer on the 4.2's. DOH. I learned the hard way! only took a couple minutes to redo. no biggie.

I also took the knock sensor out and put in the plug from the 3.8. The 3.8 has a nice plug for where the knock sensor goes. made an easy transfer.

just thought I'd share my experiences.

[Justang2k]

Ok, is my car odd?
When I had the stock dipstick and dipstick tube it didn't say full untill I had 6qts of oil in it.
Now that I have the 4.2 dipstick and dipstick tube it does the same thing. 6qts of oil and it's full.
If I have 5qts in, it says on 1qt low. always has.

why is this? I've always ran 6qts of oil.

btw, I had to go with the 4.2L dipstick tube because my other one got bent when shuffling the parts around.

[marvinmycat]

Sorry for this stupid question but...

What 4.2L blocks are we talking about, an F-150?

If so, is there a recommendation to go with the same year blocks?

Thanks.

[pete]

Originally Posted by marvinmycat

Sorry for this stupid question but...

What 4.2L blocks are we talking about, an F-150?

Yes. It doesn't have to be the same year.

[Justang2k]

bump

good information...

[RGR]

top

[plstktnkr2]

I purchased a older 87 block from a J/Y and I have modified it by dropping in 4.2 parts(yes they will fit) plus 4bbl intake will fit. so will 5.0 W/P . I didnt get a 4.2 engine because i had the same problem as another member (no engines in my area)

[RGR]

really nice combo

The carb will be great on a 4.25 liter setup,
with big valves and all that!

[plstktnkr2]

It is also good to know that super coupe head gaskets (ie beefier) will also fit the regular 3.8/4.2