440 Six Pack Rod Journal Size: Bearing Clearances and Sizes
The 440 Six Pack or 6-BBL rod journal size is a question which comes up often. Let’s examine what the 440 Six Pack rod journal size is.
The 440 Six Pack rod journal diameter is 2.374″-2.375.” The rod bearing bore size or outside diameter of the rod bearing is 2.5000″-2.5005.”
This article will explain the journal measurements and sizes in more detail. In addition, it will include the factory allowable out-of-round, taper and crankshaft bearing clearances.
440 Six Pack Rod Journal Size
Connecting rod bearings are not one of the first engine parts talked about. Although they are one of the most important.
When checking for bearing clearances or purchasing connecting rods, knowing the factory specifications are something people should know.
The rod journal and bore size remains the same for all three years. There are differences in clearances. Those differences are shown below.
Let’s take a close look at the rod journal, bore and bearing sizes.
Crankshaft: 440 Six Pack Connecting Rod Journal Size
The connecting rod journal size is the diameter of the rod journal on the crankshaft. It’s what the big end of the rod bolts on to.
Mopar big blocks have four of them, each one sharing two connecting rods each.
- The 440 Six Pack rod bearing journal diameter is 2.374″-2.375″ (2.375″).
- The maximum allowable out-of-round and/or taper is .001″
440 Six Pack Connecting Rods: Bearing Bore Diameter
The rod bore size is the inside diameter of the rod bearing housing without the bearings installed. It’s also the outside diameter of the rod bearing.
- The 440 Six pack rod bearing bore diameter is 2.5000″-2.5005″
Rod Bearing Clearance
The rod bearing clearance refers to the space between the outside diameter of the rod journal and the inside diameter of the rod bearing.
The space or clearance allows a cushion of oil between the journal and bearing.
The following chart indicates the rod bearing clearances for all three years of the Six Pack/6-BBL engine:
| Year | 440 Six Pack Rod Bearing Desired Clearance | 440 Six Pack Rod Bearing Maximum Clearance |
| 1969 | .001″-.002″ | .0025″ |
| 1970 | .001″-.002″ | .0025″ |
| 1971 | .001″-.002″ | .0025″ |
Remember, higher performance engines require more bearing clearance than factory stock. The following video describes that plus bearing information.
Two tools are required when checking the clearances on the connecting rod bearings:
- Micrometer to measure the rod bearing journals.
- A dial bore gauge to measure the inside diameter of the Hemi rod bearing.
The rod 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.
If you’re interested in the main bearings journal size, bearings and clearances, check my article, 440 Six Pack Main Bearing Size.
If you have any questions about rods, bearings, posts or more information you’d like to contribute, send us an email found specifically on our contact page.
More Rod Journal Articles
For the past 40 years, I’ve been studying and researching Mopar engine specs, rods and bearings like the 440 Six Pack. I’ve assembled 440 Six Pack engines, read books, articles, magazines, watched videos, attended seminars and spoken to other Mopar experts about the topic.
Read More Six Pack and Mopar Engine Articles!
Article Resources
- Mahle: Performance Engine Bearings
- Mahle: Chrysler Bearings
- Google Books: Chrysler Engines 1922-1998
- Plymouth and Dodge Service Manuals: 1966-1971
