The factory specs include 2.450-inch main bearing journals and 2.100-inch rod journals, which means the target bearing clearance should be
about 0.0024-inch
(0.0025 is the common spec) on main bearings and 0.0021-inch on the rod bearings.
How is bearing thickness measured?
Remember, always measure bearing wall
thickness at the bearing centerline (90 degrees from the parting lines)
. Measuring at the parting line, will likely result in an error of . 001” or more due to eccentricity and parting line relief.
How are rod bearings measured?
Measuring the inside diameter of a main or rod bearing will require a
dial bore gauge
. The best ones are accurate down to 0.0001-inch and generally come as a set that offers a measurement range from 2 inches to 4 inches inside diameter (id). With these two tools you can quickly determine the clearances in any engine.
How are connecting rods measured?
A Connecting Rod is measured
between the centers of the crankshaft journal bore and the piston pin bore
. It can be listed in inches or millimeters. The connecting rod’s length will impact Rod Ratio . Also, changing the rod length will require new pistons with the correct Compression Height .
How do I know if my rod bearings are oversized?
An oversized bearing
has the same inside diameter but a bit more material on the outside diameter
. An undersized bearing measures the same outside but is thicker on the inside.
What is standard bearing clearance?
Bearing internal clearance (fig. 1) is defined as
the total distance through which one bearing ring can be moved relative to the other in
the radial direction (radial internal clearance) or in the axial direction (axial internal clearance).
What does a bad main bearing sound like?
Rod knock means there is too much clearance due to the bearing wear, causing the rod big-ends to beat against the crankshaft. Therefore, rod knock is a huge symptom of bad engine bearings and means a bad engine bearing sounds like
a knocking sound
.
How do you calculate the length of a rod?
Subtract the total length of the halved inner diameters and the metal wall on the ends of the rod from the total length of the connecting rod
. This number will be the final measured length.
What is the best rod ratio?
Some engine builders say a “good” rod ratio is anything
1.55 or higher
. Production engines may have rod ratios that range from 1.4 to over 2.0, with many falling in the 1.6 to 1.8 range. Four cylinders tend to have lower rod ratios (1.5 to 1.7 range) while many V6s have somewhat higher rod ratios of 1.7 to 1.8.
What is the rod length on a 327?
| Displacement Cubic Inches Liters Rod Length(inches) | 327 5.4 5.700 | 350 5.7 5.700 | 350(LT5) 5.7 5.700 | 350(LS1) 5.7 6.098 |
|---|
How do I know if my rod bearings are standard?
Measuring the inside diameter of a main or rod bearing will require
a dial bore gauge
. The best ones to use are accurate down to 0.0001-inch. With these two tools you can quickly determine the clearances in any engine. Measuring bearing clearance is only valuable if the numbers are accurate so use quality tools.
Why would you need oversized rod bearings?
Undersized bearings are used when a crankshaft has been machined or ground undersize. Oversize bearings
have more material on the outside facing the bearing housing bore
. Oversized bearings are used when the block has been machined or line bored oversized.
Are rod bearings and main bearings the same?
The main bearings support the crankshaft in the engine block and the rod bearings support the
connecting rods
on the crankshaft.
What does C mean on a bearing?
The C code of the bearing indicates
how much internal clearance the bearing gets in the machine
.
How do you read a bearing number?
- The first number i.e. ‘6’ represents the “type of bearing”.
- The second number i.e. ‘2’ represents the “ bearing series”
- The third and fourth number i.e. “03” represents “bore size”
- And the last two letters i.e. “RS” represents the “Sealing/ Seal”
What are the three types of bearings?
There are several types of bearings, the four main types are:
ball bearings, cylindrical roller bearings, tapered roller bearings and needle bearings
. While ball bearings are the most common mechanisms, each device has its advantages and disadvantages.
