Camshaft bearings: types, oil holes, sizes & tool reference
A camshaft bearing supports a camshaft journal. It is not the roller that follows a cam lobe. Depending on the engine, the support may be a replaceable plain bearing, a shell, a rolling bearing or a bearing surface in the head or carrier. Identify the exact engine, position and construction before comparing a set, size or installation tool.
On this page18 sections ⌄
Cam bearing, journal, cap and roller follower: what is different?
On smaller screens, scroll the table sideways to read all columns.
| Term | Meaning | Identification boundary |
|---|---|---|
| Camshaft journal | The shaft surface supported by a bearing | Journal diameter is not automatically the housing bore. |
| Camshaft bearing or bush | The support around the journal | Construction and replaceability depend on the engine. |
| Camshaft bearing cap/carrier | Part of the supporting housing arrangement | It is not automatically a separate replaceable bearing shell. Do not infer cap interchange, order or bolt torque. |
| Roller follower or roller tappet | A roller interacting with a cam lobe | A roller-cam description does not prove that the cam journals use roller bearings. |
| Needle-roller camshaft support | Rolling elements supporting a camshaft journal | NSK documents drawn-cup needle designs for this position; an actual engine match is still needed. |
Babbitt, aluminium alloy and layered materials
MAHLE contrasts forgiving babbitt linings with stronger but less contamination- and misalignment-tolerant aluminium alloy. Material choice is an application trade-off, not a universal best-bearing ranking.
Dura-Bond describes its bimetal construction as a steel tube with a lead-based babbitt layer. That is a named construction example, not a claim that every cam bearing uses the same alloy. A coating, lining and backing are different layers; retain the manufacturer's material designation when comparing parts.
Neither a colour photograph nor the word performance establishes the required material, coating, clearance or permissible load. A coated candidate must still match its documented engine application.
Oil-hole alignment and clock position: when does 2 o'clock apply?
MAHLE specifies hole alignment where the block has no rear groove. For a grooved block, its advice places the hole at 2 o'clock viewed from the front with normal clockwise cam rotation. Those conditions matter; it is not a rule for every engine.
For an SBC/350 or other engine query, establish the actual oil-feed geometry, viewing direction, rotation and installation depth before applying a clock position. A family nickname alone does not establish these conditions. A drawing and the current engine/bearing instructions must resolve them.
Camshaft diameter, bearing OD, housing bore and oil clearance
The engine-reference catalogue displays original inch shop-data values where a complete, consistent source row is available. A housing-size example is not a running-clearance recommendation. Do not fill a missing measurement with a value from a similarly named engine.
On smaller screens, scroll the table sideways to read all columns.
| Field | Keep it separate from | What to record |
|---|---|---|
| Standard shaft diameter | Housing bore or bearing outside diameter | The journal and its catalogue/application position |
| Bearing OD / housing field | Installed bearing ID | The original column label and any OD repair-size condition |
| Oil clearance | Interference between bearing and housing | Measurement method, assembled condition and engine-specific limits |
| Maximum wall or length | A nominal generic size | The source's maximum qualifier and units |
| Set number | A single member dimension | Members, positions, quantities and application notes |
Three documented Small Block Chevrolet oversize-OD examples
MAHLE's special-set examples below are for specified align-bored housings, not a stock-bore substitution. Values are housing dimensions in inches, not journal diameters or running clearances.
These examples answer what an oversize-OD designation can refer to. They are not machining instructions or proof that an arbitrary block can accept the set. Verify the exact block, repair specification and complete bearing instructions.
On smaller screens, scroll the table sideways to read all columns.
| Set | Published OD repair size | Housing bore in | Source qualifier |
|---|---|---|---|
| SH-1352S | +0.010 in | 2.030–2.031 | Five equal-size bearings |
| SH-1401S | +0.020 in | 2.040–2.041 | Special oversize set |
| SH-1528S | +0.010 in | 2.030–2.031 | TriMetal construction |
SH-2125S and SH-290S: set numbers versus member bearings
These identification records come from the checked MAHLE/Clevite EB-20-26 catalogue data already used by the engine-bearing lookup. The full application blocks remain on their existing reference pages.
A member list is not an installation-order or quantity table. Several application blocks can refer to one set, and a package identifier is not one universal shaft size. The lookup retains incomplete or conflicting shop data as unresolved instead of copying a guessed number.
Search text such as sh2125s or sh290s is useful for discovering these printed set numbers. It does not establish that either set fits every 5.3, LS, Chevrolet or other engine sharing a nickname.
On smaller screens, scroll the table sideways to read all columns.
| Set | Named member numbers in the checked entries | How to use the record |
|---|---|---|
| SH-2125S | SH1995 · SH2124 · SH2125 | Open the set reference and read the matching engine/application block. |
| SH-290S | SH287 · SH288 · SH290 | Check the member entries and their source-status notes; not all shop dimensions are resolved. |
A documented cross-reference can be one-way
Dura-Bond's technical FAQ says CH-25 may substitute for CH-23, but not the reverse. This is a manufacturer-stated direction, not permission to treat all CH-series numbers as equivalent.
Keep the direction, source and application restrictions in a cross-reference record. The statement alone does not supply a full dimension table, all engine applications or an installation specification for either set.
Lisle 18000: tool range, collets and sleeve-set references
Lisle identifies 18000 as an expanding cam-bearing removal/installation tool. Its listed bearing-ID range is 1.125–2.690 in (28.58–68.3 mm). Tool capacity is not an engine fitment list.
The manufacturer specifies brown sleeves for 0.065 in thin-wall bearings and black sleeves for 0.090 in thick-wall bearings. Its T18000 instruction sheet governs assembly and operation. This table identifies components; it is not a substitute for those instructions.
Before selecting a driver, verify access, reach, alignment and support as well as bearing ID. The word universal does not establish suitability for every engine, blind position or bearing construction. No homemade tool, improvised puller or tool-free removal method is recommended here.
On smaller screens, scroll the table sideways to read all columns.
| Bearing ID in | Expander / collet | Washer | Sleeve set |
|---|---|---|---|
| 1.125–1.475 | 18330 | 18430 | 18410 |
| 1.475–1.700 | 18020 | 18430 | 18120 |
| 1.700–1.925 | 18040 | 18420 | 18140 |
| 1.925–2.150 | 18060 | 18420 | 18160 |
| 2.150–2.375 | 18080 | 18420 | 18180 |
| 2.375–2.690 | 18100 | 18420 | 18200 |
Installing a bearing is not the same as machining its housing
Dura-Bond lists an expanding cam-bearing tool and a separate Quick Bore system for aluminium OHC heads. Its tool reference includes 1.370, 1.682, 1.875 and 2.250 in mandrel/sleeve sizes and 5, 24 and 36 in driver bars; the 24 in bar is listed separately. These are tooling identifiers, not finished camshaft sizes.
Line boring concerns the supporting bore geometry. It is not achieved by selecting a bigger driver or forcing a tight bearing into place. A driver, puller, reamer and line-boring system have different purposes. The exact repair must follow the identified engine and tooling procedure.
Worn, scored or spun: what evidence does the lookup need?
The engine-bearing failure guide explains how wear mechanisms and measurements are recorded. These observations are evidence prompts, not a diagnosis for a 5.3, LS, Cummins, Harley or other named engine. Engine-specific limits and repair decisions remain separate data requirements.
MAHLE warns against honing bearing IDs because abrasive particles can become embedded. This is not an endorsement of another unverified clearance-correction method.
On smaller screens, scroll the table sideways to read all columns.
| Observation | Record before disturbing the evidence | Do not conclude |
|---|---|---|
| Scoring or embedded particles | Position, surface photographs, oil/filter evidence and contamination history | That a new material alone corrects the cause |
| Uneven contact or binding | Journal and bore measurements, alignment checks and installation history | That it should be forced through or allowed to wear itself loose |
| Bearing displaced in its housing | Original position, oil-hole relationship and housing condition | That replacing only the bearing restores the original fit |
| Noise, low pressure or debris | Operating conditions and measured findings from the actual engine | A confirmed cam-bearing diagnosis or safe running distance |
What an engine-specific answer still needs
An unresolved specification stays unresolved. A generic guide or a real example from a different engine does not count as a completed model-specific answer.
On smaller screens, scroll the table sideways to read all columns.
| Unresolved request | Required evidence |
|---|---|
| LS/Gen III/Gen IV, Ford, Cummins, Harley or another engine fitment | Exact engine and build range, bearing positions and current catalogue/service information |
| A 50/55/60 mm or other roller-cam conversion | Matched bearing, shaft, housing and oil-system engineering data |
| Cap replacement or bolt torque | The identified head/carrier procedure, position markings and fastener specification |
| Installation or removal steps | The engine-specific access, depth, orientation, tools and inspection limits |
| Best, coated or racing selection | A defined application and comparable material/load/lubrication evidence |
What the evidence can — and cannot — tell you
| Observation or context | Interpretation to consider | Verification needed |
|---|---|---|
| An engine family such as LS or SBC | A search scope, not a complete specification | Keep the engine code, build range, block and bearing position. |
| A set or kit number | A package identifier | Check its member bearings and source application notes. |
| An oversize dimension | A size change that needs an identified surface | Separate housing/OD repair size from journal size and running clearance. |
A practical investigation sequence
Identify and record
Record the exact engine/block, rotation convention, camshaft and bearing positions; preserve the old part markings.
Check the context
Find the catalogue application and set/member entries, then check housing, shaft, clearance and oil-feed fields separately.
Verify before acting
Identify the service method and correctly sized tooling from the engine and tool instructions; retain orientation and depth requirements.
Keep the decision traceable
Document inspection measurements and unresolved limits. Do not machine, substitute or return the engine to service using a generic example alone.
Capture the information a model search cannot guess
Keep this checklist with your inspection or comparison. Checking a box only records that you have collected the item; it does not certify the bearing.
0 of 4 information groups recorded.
Technical basis & editorial scope
Original BearingScope workflow, written for catalogue research and comparison. Manufacturer material is used to check principles, not copied as a product endorsement or substituted for model-specific instructions. Reviewed 1 October 2026.
- MAHLE — Cam bearing performance and scoped oversize examples — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- NSK — Engine parts — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- Lisle — 18000 camshaft bearing tool and component ranges — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- Dura-Bond — Engine bearing construction — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- Dura-Bond — Cam bearing tooling — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- Dura-Bond — Technical FAQ, directional CH-25/CH-23 reference — Automotive component identification and named examples only. No universal vehicle fitment, machining tolerance or repair procedure. Reviewed 2 October 2026.
- MAHLE/Clevite — EB-20-26 engine-bearing catalogue (2026), selected checked entries — Engine journal-bearing reference; preserve source edition, units, part/package and application qualifiers. No universal service tolerance or current fitment approval. Reviewed 2 October 2026.
- King Engine Bearings — Bearing Terminology — Shell identification, undersize/oversize and spin terminology
- King Engine Bearings — Engine Bearing Failures — Failure evidence and contributing conditions
Source addresses and collection status are retained in the internal audit. No unpublished dimensions, torque settings, service intervals or interchange approvals are inferred.