by Scott Paisley and Chris Kantarjiev, firstname.lastname@example.org
I thought I would relate my experiences with TR6 Oil Presure, based on my engine before and after my engine rebuild of a few years ago:
A fresh TR6 engine Oil pressure values:
Cold Idle 90+
Cold Running 100
Warm Idle 40
Warm Running 70
A worn TR6 engine might look like this, based on my engine before rebuild:
Cold Idle 50
Cold Running 70
Warm Idle 15
Warm Running 50
In some cases, replacing the big-end bearings on the connecting rods will help low idle oil pressure. The low pressure can be an indicator to the fact that there is slop there, and oil leaks out falling back into the oil pan. Removal of the pan and replacement of these bearings is a simple fix if a rebuild is not possible. Some manuals even recommend replacing these bearings every 50,000 miles! (Bentley, I think...) By the way, 20w50 will raise oil pressure values, but not too significantly after the car becomes completely warm.
Also, people suffering from low pressure should look at the rocker shaft. They get fairly worn and people don't notice. This is usually indicated by the oil pressure fluctuating with the engine at steady revs.
To check it, loosen the rocker adjuster and see if there's any side to side play. A little is OK, but there really shouldn't be any. The next check is to push the rocker aside (towards one of the spring spacers) and run your finger over the bottom of the shaft. It should be perfectly smooth. If there are any ridges big enough to catch a fingernail on, replace it - there's a thin top layer that's been hardened, and when that is worn through, the wear accelerates rapidly.
The major Triumph car parts suppliers have most everything needed to rebuild and rebush the rockers, but one of the two types of rocker arm is NLS. The parts are not cheap, and sizing the bushes with a reamer is exacting work and requires an adjustable reamer. For less than the cost of a new shaft and bushes, you can send your complete assembly to a specialist and have them do the work. One such shop is "Rocker Arm Specialists" - they replace the shaft with a hard chromed version, renew the bushes and reface the rocker arm pads. They do lovely work.
Rocker Arm Specialists
19841 Hirsch Street
Anderson, CA 96007
Phone: (916) 378-1075
-Written by Scott Paisley, 75TR6 and Chris Kantarjiev