440 Main Bearing Size: Journal and Bearing Bore Sizes

The 440 Mopar main bearing size, main journal and bore size is often asked. Let’s take a close look at each one.

The 440 main bearing journal size (diameter) is 2.7495″-2.7505.” The outside diameter of the main bearing or the main bearing bore size is 2.9425″-2.9430.”

This article will take a deeper dive into the details of each measurement. In addition, I’ll include the factory desired and maximum clearances and other main bearing specifications.

440 Main Bearing Size

When making purchases, checking clearances or just curiosity, you may want to know the factory specifications.

The 440 main bearing journal and bore remain the same for all years. There are differences in bearing material and clearances between the years. Those differences are shown below per year.

For the purpose of this article and website in general, this article will concentrate on the “muscle car era.” I’ll examine the 440 from 1966 to 1974.

The main bearings may be a small engine part but they’re important and is anything but small. Let’s examine the main journal first.

440 Main Bearing Journal Size

The main bearing journal size is the diameter of the main bearing journal on the crankshaft.

The 440 main bearing journal diameter is 2.7495″-2.7505.”
The maximum allowable out-of-round and/or taper are .001″

440 Main Bearing Bore Size

The main bearing bore size is the inside diameter of the main bearing housing without the bearings installed. It’s also the outside diameter size of the main bearing.

The 440 main bearing bore size is 2.9425″-2.9430.”

440 Main Bearing Clearance

The main bearing clearance refers to the space between the outside diameter of the crank journal and the inside diameter of the main bearing.

The space or clearance allows a cushion of oil between the journal and bearing.

When checking the main bearing clearances on your 440, two tools are required:

A dial bore gauge to measure the inside diameter of the main bearing.
A micrometer to measure the main bearing journals.

The main bearing journal diameter can be checked with a precision micrometer sized for the range of the journals you will measure.

There are many cheap micrometers out there for sale you should avoid. Use a quality micrometer that will measure down to the 0.0001-inch.

Also, the best dial bore gauges are accurate down to 0.0001-inch. The two tools can be purchased as a set offering measurements from the 2-4″ range.

Disclaimer: Some of the links in this article may be affiliate links. As an affiliate associate, I may earn a commission for qualifying purchases at no extra cost to you.

Check out quality dial bore gauges and micrometers at Jegs High Performance, Dial Bore Gauges and Micrometers.

1966 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt
Thrust Bearing is the #3 main bearing
End Play: .002″ to .007″
Clearance Desired: .0005″ to .0015″
Maximum Clearance Allowable: .0025″

1967 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt
Thrust Taken By: #3 Bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.0015″
Clearance Allowed: .0025″

1968 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt
Thrust Taken By: #3 Bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.0015″
Clearance Allowed: .0025″

1969 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt
Thrust Taken By: #3 Bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.0015″
Clearance Allowed: .0025″

1970 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt*
- * #3 Bearing is Tin Aluminum Alloy Steel Backed
Thrust is taken by the #3 main bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.0015″
Clearance Allowed: .0025″

How to check main bearing clearances and check their sizes.

1971 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt*
- * #3 Bearing is Tin Aluminum Alloy Steel Backed
Thrust is taken by the #3 main bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.002″
Clearance Allowed: .0025″

1972 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced
Bearings: Steel Backed Babbitt*
- * #3 Bearing is Tin Aluminum Alloy Steel Backed
Thrust is taken by the #3 main bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.002″
Clearance Allowed: .0025″

1973 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced or Externally balanced
Bearings: Steel Backed Babbitt
- Hi-performance: all bearings Tin Aluminum Alloy Steel Backed
Thrust is taken by the #3 main bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.002″
Clearance Allowed: .0025″

1974 Crankshaft/Main Bearing Specs and Clearances

Type: Fully Counter-Balanced or Externally balanced
Bearings: Steel Backed Babbitt; #3 thrust aluminum
- Hi-performance all bearings: Tin Aluminum Alloy Steel Backed
Thrust is taken by the #3 main bearing (Thrust Bearing)
End Play: .002″-.007″
- Maximum Allowable: .010″
Clearance Desired: .0005″-.002″
Clearance Allowed: .0025″

These are tight clearances but remember the factory often recommends a tighter clearance than race engines.

Additional 440 Main Bearing Fact: In 1974 and after, the diameter of the thrust bearing’s outer edge was increased. The machined recess areas for the outer edge of the thrust bearing was also increased in the block and main bearing cap.

If you have any questions about the main bearing shell, posts or more information you’d like to contribute, send us an email found specifically on our contact page.

This video shows how to use a micrometer and dial bore gauge while checking clearances and installing main bearings

For the past 40 years, I’ve been studying and researching Mopar engine specs like the 440. I’ve assembled 440 engines, read books, articles, magazines, watched videos, attended seminars and spoken to other Mopar experts about the topic.

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