Narrow vs. Wideblock FAQ

[MainstreaM]

I see this toooo much on the boards and needs to be a sticky. Here goes.

 

Q:

What is this wide block/narrow block I keep hearing about.

 

A:

Mitsubishi designed their four cylinder engines with two different transmission mounting patterns. They are commonly referred to as Wide Block and Narrow Block.

 

The Wideblock:

In the late 70's, when the design work was being done on a new family of engines, there were no front wheel drive cars only rear wheel drive. Mitsu came up with their first pattern then, what we refer to as the Wide Block. It allowed a larger clutch setup which in turn allows more clamping grip with less pressure plate force. Tried and true it was done this way previously released engines as well.

 

The Narrowblock:

In the early 80's the front wheel drive platform was rolled out. It allowed for a more compact drivetrain with fewer parts. Theoretically that meant lower failure rates. The wideblock pattern that was so common on the rear wheel drive would not fit the front wheel drive platform. It was possible that it could fit but engineering design constraints called for a smaller block mounting foot print for optimum transaxle shaft placements (shafts inside the FWD transmission). The decision was made to implement the Narrowblock pattern, in turn the smaller flywheel needed a higher clamping force from the pressure plate. (It is speculated that this higher clamping force is the source of crankwalk) Why the narrow block was used in the manual trucks after 85 or so, that's anybody's guess.

 

Q:

How do I tell which engine I have?

 

A:

2.0 G63B Manual Transmission will be a Narrow block. You can tell by measuring 12.25 inches between the lower bell housing bolts.

 

2.0 G63B Automatic Transmission will be a Wide block. You can tell by measuring 13.25 inches between the lower bell housing bolts.

 

2.4 G64B All Transmissions will be a Wide block. You can tell by measuring 13.25 inches between the lower bell housing bolts.

 

2.6 G54B All Transmissions will be a Wide block. You can tell by measuring 13.25 inches between the lower bellhousing bolts.

 

Q:

Where do I measure?

 

A:

Make sure you measure center to center.

Like this:

http://img367.imageshack.us/img367/9958/p1010073fz2.jpg

 

Q:

Can I swap my _____ block for a _____ block?

 

A:

No the size difference won't allow it. There is also a difference in the bolt spacing on the upper bell housing bolts. We measure from the bottom because it is usually easier to get to. It can be done but you have to use the matching transmission, at which point it isn't an engine swap anymore.

 

Q:

Can I swap flywheels?

 

A:

No. The wideblock flywheel will not physically fit inside the bellhousing on a narrow block. The narrowblock flywheel will not reach the starter gear teeth on a wideblock.

All six bolt wide block flywheels will interchange between engines.

All six bolt narrow block flywheels will interchange between engines.

This means the wideblock guys can use aluminum flywheels meant for the Starion/Conquest G54B.

 

Q:

What about the rest of the engine? Pistons, cranks, oil pumps, etc. Will it swap?

 

A:

Yes with conditions. So long as you stay in your engine family everything will swap between the two blocks. That means G63B narrow block pistons will fit a G63B wideblock. G54B Wideblock rods will NOT fit a G64B Wideblock and so on.

 

Q:

You mentioned six bolt earlier, whats that mean.

 

A:

Sometime during the mid-year for 1992, Mitsu decided to go upgrade (?) the six bolt platform in sirius line of engines. The new design was basically the same engine with a few differences. The most noticeable was the flywheel. It went from six bolts to seven holding it on. Hence the designation six and seven bolt. Another notable difference was with the oil pump and pan. The six bolt had a straight rail across the bottom of the pump for the pan to bolt to. The seven bolt pump curved out to allow room for a new crank position sensor. The biggest difference that most people don't know about was with the main and rod bearings. They now had much, much tighter tolerances. So tight that bearings were individually sized for each main and rod journal. No more buying them in a set. You had to measure the crank with a micrometer and order the correct bearing from Mitsu. The bad news is the only RWD platform for the G64B 7 bolt is the Mighty Max, so aftermarket performance flywheels and clutches are non existant.

 

Q:

It's really dirty under my truck and I might get grease under my fingernails, is there a list I can look at to see what engine my car or truck has in it.

 

A:

Yes:

http://img100.imageshack.us/img100/7079/mitsubishienginescw0.gif

Thanks to www.projectzerog.com

 

 

 

Got anymore info? Post it up and I'll add it in.

 

Kane

Edited April 11, 2008 by MainstreaM

[cengic@sbcglobal.net]

Wow, seems like someone finally knows about wide block transmissions. What are the limits in horsepower and torque of the transmission?

[vr4x4]

So im noticing on that list that they dont talk about 4g63 wideblock, what did those come in?? anyone know.

[MainstreaM]

Q:

How do I tell which engine I have?

 

A:

2.0 G63B Manual Transmission will be a Narrow block. You can tell by measuring 12.25 inches between the lower bell housing bolts.

 

2.0 G63B Automatic Transmission will be a Wide block. You can tell by measuring 13.25 inches between the lower bell housing bolts.

 

2.4 G64B All Transmissions will be a Wide block. You can tell by measuring 13.25 inches between the lower bell housing bolts.

 

2.6 G54B All Transmissions will be a Wide block. You can tell by measuring 13.25 inches between the lower bellhousing bolts.

 

 

This article was orginally written for a Mitsubishi Mighty Max / Dodge D50 forum. Those are the vehicles you will find the 4G63 wide block in.

 

Truck transmissions are weak. B2600/TII swap or a Bill Hincher adaptor is suggested. Starion trans at the minimum.

 

Kane

[Paul L]

just to make sure i got this right. my manual g54b tranny will fit on a d50 or mighty max wideblock. correct? im trying to read up information on d50/might max blocks with 4g63 head and starion tranny's.

[76ColtGalant]

The Wideblock:

In the late 70's, when the design work was being done on a new family of engines, there were no front wheel drive cars only rear wheel drive. Mitsu came up with their first pattern then, what we refer to as the Wide Block. It allowed a larger clutch setup which in turn allows more clamping grip with less pressure plate force. Tried and true it was done this way previously released engines as well.

 

The Narrowblock:

In the early 80's the front wheel drive platform was rolled out. It allowed for a more compact drivetrain with fewer parts. Theoretically that meant lower failure rates. The wideblock pattern that was so common on the rear wheel drive would not fit the front wheel drive platform. It was possible that it could fit but engineering design constraints called for a smaller block mounting foot print for optimum transaxle shaft placements (shafts inside the FWD transmission). The decision was made to implement the Narrowblock pattern, in turn the smaller flywheel needed a higher clamping force from the pressure plate. (It is speculated that this higher clamping force is the source of crankwalk) Why the narrow block was used in the manual trucks after 85 or so, that's anybody's guess.

 

Sorry for million year reply, but that is some misinformation right there.

As per the Astron family of engines stateside,

 

The 4g54 (not later 4g54b) came in a mix of wide and narrow block versions between the 70s to early 80s. All 4g52s are Narrow Blocks, this was a common motor in 74-79 Colts (base models with Auto, GT/Carousel models had the option for MT or AT), 76-80 Arrows 78-early 80s pickups with 2.0s before being phased out with the g63b. Late 70s Colts (lancers) and Arrows (Lancer Celeste) brought the introduction of the 4g54 in their GT Models and The Fire Arrow.

 

Narrowblock RWD Manual trans found in colts,arrows and trucks

KM110 = 4spd

KM119 = early 5spd (70s)

KM132 = 5spd Introduced into the Lancer based Colts and Arrows of the late 70s, as well as early pickups, share same tailshaft size (small yoke) as the earlier KM110/KM119.

 

Astron 1 (4g54/4g52/4g52b) Heads have a different stud pattern on the intake side of the head, 4g52 was non-jet valve and dizzy mounts to timing case instead of in the head, 4g52b is jet valve and dizzy located in the head like a 4g54b (Astron 2).

 

So, with all that, Narrowblock Engines have been around longer prior to 80s, all Saturn family (4g3x) are also narrowblocks. Which the 4g32 has been around since '71.