Old Britts, Cylinder Head Information

Cylinder Head Information

This article is a work in progress and will eventually address all the work and parts that may go into rebuilding a cylinder Head.

Rocker Arm Spindle removal and installation

Using the factory slide hammer to remove the rocker arm spindle. You need to heat up the head prior to removing or installing the rocker arm spindles. This slide hammer is described in our article at: Slide Hammer .

Using a rocker arm spindle puller. Some times the rocker arm spindles are too tight to remove with the slide hammer so you may need to make a puller. In most cases the slide hammer works just fine.

Installing the rocker arm spindle.

Let the spindle stick through the side of the head enough to fit the thrust washer on the spindle. The flat on the rocker arm spindle for Commandos must face out from the center of the head. For Atlas heads, with rocker oil feed at the top of the head instead of the side of the head, the flats face tward the center of the head.

Rocker arm spindle checking tool. You can make a tool fron safety wire to check how the spindle is alligned. This tool lets you find the oil hole in the flat on the spindle.

Valve Information

Old Britts stocks two manufacturers of valves for Norton Commandos. Both stock 750cc and 850cc engines use the same size intake valves and exhaust valves. We stock valves from Andover Norton and Kibblewite Precision Machining, Inc. (Black Diamond Valves).

All sizes in the following table are in inches and all prices listed are current as of 02/12/21.

Part No.	Type	Manufacture	Head Dia.	Stem Dia.	Length	Price
06-5115	Exhaust	Andover	1.303	0.311	4.020	$34.70 each.
06-5115/P	Exhaust	Kibblewite	1.300	0.3107	4.015	$34.98 each.
06-5115/P6	Exhaust	Kibblewite	1.360	0.3107	4.005	$34.98 each.
06-4034	Intake	Andover	1.488	0.311	4.070	$35.89 each.
06-4034/P	Intake	Kibblewite	1.500	0.3107	4.065	$34.98 each.
06-4034/P6	Intake	Kibblewite	1.560	0.3107	4.055	$34.98 each.

New valves from left: 06-5115,06-5115/P, 06-4034, 06-4034/P.

Lash Cap Information

The purpose of using lash caps is to protect the top of the valve stem, allowing the replacement of the lash cap if they get pitted and providing a larger foot print for the valve adjusters. As you can see in the second picture the used valve has pitting caused from the valve adjuster rubbing across the valve stem.

The lash caps we use are from Kibblewite Precision Machining, Inc., part number 11-700816, $9.35 each.

The lash caps extend the valve stem by .078" requiring the valve stem to be shortened by that amount. The lash caps should be able to rotate on the valve stem so they can be removed and installed when the valve is installed in the head. We can grind down a set of four valve stems for our lash caps, part number 11-700816/MV, $100.00. We check the length of the ground down valve with and without the lash cap installed.

Lash caps

Valve with lash cap next to used valve.

Using a converted drill sharpener to grind down a valve stem for a lash cap.

Check the length of a valve using a height gauge.

Lapping the valves and checking the valve seating

I check the valve leakage prior to dismantling the head for a point of reference. In the following picture the left side registered 8% leakages and the right side around 95%. This told me that the valve seats were probably fine and all I needed to do was lap in the new valves. After lapping the valves I did achieve 0% leakage for all four valves. With the head bolted to a bottom plate it is possible to achieve 0% leakage, since only the valves are being tested not the valves and pistons.

Head bolted to the leak down bottom plate and being tested.

I use two types of lapping compound, Course and Fine. I use the course first then use the fine. I use a small brush to apply the compound to the valve seat.

Applying lapping compound to the right exhaust seat.

You can use a suction lapping stick to manually rotate the valve in the seat.

One way to lap a valve in a seat.

I use a drill attached to the valve stem by a rubber hose to turn the valve in the seat.

Another way to lap in a valve.

You need to keep the valves with the seats that you have just lapped so they go together when assembled.

One way to keep valves organized.

future information

Return to Old Britts home page ….. Our Products, Ordering
Norton Parts….Engine, Valve Gear

This page was written and designed by F. H. Eaton & Associates if you have any questions or comments please contact us at infon@fheaton.com