Originally Posted by 3.8mustang.com

I didn't see this info here in one post so I thought it should be posted.


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.