Description

Nissan R, H20, H30 1967 Service Manual – Factory Metric Thread Conversion

If you’re working on a Nissan R, H20, or H30 engine from 1967, you already know the parts book looks like two different languages. Inch threads mixed with metric bolts – that’s a recipe for stripped holes and broken studs if you don’t have the right documentation. This 20-page factory service bulletin is what you need on the bench. It documents exactly when and where Nissan switched from inch to metric threads, and which fasteners stayed inch. Without it, you’re guessing.

This factory-issued service bulletin (Publication No. 77171) from January 1967 covers the introduction of metric standard threads and the new 5-bearing crankshaft support for the R and H20 engines. At only 20 pages, it’s dense with conversion tables and serial number ranges.

What the Nissan R, H20, H30 1967 Service Manual Contains

The table of contents is short but critical. Chapter I covers the Metric system for all three engines, splitting into I-A (Parts fitting to cylinder) starting on page 1, and I-B (Cylinder head parts) starting on page 7. Chapter II addresses the 5 bearings supporting system for the R and H20 engines from page 10 onward. Each section lists the exact parts affected and the new thread sizes. Page 1 gives you the applied engine numbers: R-40001, H20-60001, H30-10001.

Metric System Conversion for R, H20, H30 Engines

Nissan converted screw threads to Japanese Industrial Standard metric, but they left critical fasteners in inch. Cylinder head bolts, connecting rod bolts, exhaust manifold flange bolts, and the oil filter center bolt stayed inch. The manual gives the conversion table: 1/4 inch becomes 6 mm, 5/16 to 8 mm, 3/8 to 10 mm, 7/16 to 10 mm (exception for head bolts), and 1/2 to 12 mm. Miss that exception and you’ll torque a cylinder head with the wrong socket and strip the threads.

5-Bearing Crankshaft Support – What Changed

For the R and H20 engines, the crankshaft support went from 3 bearings to 5 bearings starting at the engine numbers listed above. This meant new main bearing caps, different block machining, and a stronger bottom end. The bulletin explains the change and notes that these engines are more reliable at high speed. If you’re swapping a crankshaft or rebuilding, you need to know which support system your engine has. Page 10 starts that section.

Parts Fitting to Cylinder – Thread Identification

Section I-A details the bolts and studs that attach parts to the cylinder block. Water pump, timing cover, oil pan – each fastener gets the new metric thread. But the instruction warns: “Therefore be careful in case of dealing with the engine repair.” That’s factory speak for “don’t mix the bolts.” If you grab a bolt from an old engine without checking, you’ll damage the threads.

Engine Serial Numbers – Where the Change Begins

The manual gives the exact engine serial number thresholds. For R: R-40001. For H20: H20-60001. For H30: H30-10001. Engines below these numbers have the old inch threads and 3-bearing crank. Above them, metric and 5-bearing (except H30 which already had 5 bearings). This data is gold when you’re buying a used engine or ordering parts.

Who Needs This Bulletin

If you own a Datsun or Nissan vehicle from the 1960s with an R, H20, or H30 engine, you need this. Home garage hobbyists restoring an RL411 or C80 bus will run into these fasteners. Even professional mechanics get tripped up by the mixed thread systems on these old Nissan engines. Cross-threading a cylinder head bolt is a costly mistake this manual prevents.

Source Authenticity – Factory Print, Not Aftermarket

This is a direct scan of the original Nissan factory service bulletin, printed in Japan in 1967. No third-party rewrites, no copied diagrams from a later manual. The torque specs and thread data come straight from the OEM. Aftermarket manuals often miss the exceptions like the cylinder head bolt staying inch. This one doesn’t.

For related factory documentation, see Nissan Xterra 2005 Service Manual – OEM Factory Spec for modern models, or Nissan 60 1967 Service Manual – Original Factory Bulletin for another classic. The L-series engine enthusiasts should check Nissan L60, L60-U, KL60-U 1968 Service Manual – Factory Specs.

For broader automotive thread standard history, Automotive Industry Overview covers the metric transition. If you’re working on drivetrain components, Manual Transmission provides general knowledge.

Frequently Asked Questions

Is this manual for the R engine only?

No, it covers R, H20, and H30.

What torque specs are included?

The manual lists the metric thread conversions but does not provide torque values for every bolt. You’ll need the original engine service manual for specific torque—this is a supplement on the changeover.

How do I know if my engine has the 5-bearing or 3-bearing crankshaft?

Check the engine serial number on page 1 of this bulletin. For R engines, numbers after R-40001 have the 5-bearing design. For H20, after H20-60001. The H30 already had 5 bearings. The manual explains the exact change point and what parts differ. If you’re unsure, verify the casting marks on the block, but the serial number is your best bet. This bulletin also tells you which parts will interchange and which won’t.

Is this manual in English?

Yes, original factory English text.

That bulletin has saved me from ordering the wrong head gasket set more than once. If you’re rebuilding one of these early Nissan engines, do yourself a favor and access the factory manual. Access the Factory Manual today from AutoRepairManuals and keep it on the workbench next to your torque wrench.