Compressed Thickness of Andover Norton Composite Head Gasket?

Getting to the point where I will soon be able to do a clearance mock-up of my rotating assembly. I'm shooting for .040" quench height between my piston crown and head deck.



Rather than stacking up various thicknesses of gaskets, I would like to have the quench pad in the head deepened the necessary amount to achieve the desired quench height. Shouldn't need much more than about .010" removed.

Hoping to use the composite fire ring head gasket to prevent leaks.

Last time I removed a composite head gasket on my 750 Norton motor it was .021" smashed down. It did not leak, but I was not running a piston with as much meat on top of it as you are running.

I put a composite fire ring on my almost done and ready to start re-build, but have no intention of taking it off anytime soon to measure it after it is compressed. Damn it I probably just jinxed myself.

I'll be firing mine up tomorrow I believe. This one is going to be fun.

Schwany said:

Last time I removed a composite head gasket on my 750 Norton motor it was .021" smashed down. It did not leak, but I was not running a piston with as much meat on top of it as you are running.

I put a composite fire ring on my almost done and ready to start re-build, but have no intention of taking it off anytime soon to measure it after it is compressed. Damn it I probably just jinxed myself.

I'll be firing mine up tomorrow I believe. This one is going to be fun.

Click to expand...

I heard that the new gaskets have a thicker compressed height.

Schwany said:

Last time I removed a composite head gasket on my 750 Norton motor it was .021" smashed down. It did not leak, but I was not running a piston with as much meat on top of it as you are running.

I put a composite fire ring on my almost done and ready to start re-build, but have no intention of taking it off anytime soon to measure it after it is compressed. Damn it I probably just jinxed myself.

I'll be firing mine up tomorrow I believe. This one is going to be fun.

Click to expand...

With the stock piston compression height, the combustion chamber pressure works on the head gasket seal in a straight line around the perimeter of the combustion chamber. Since the unaltered piston crown of the set-up I hope to utilize will protrude well over .100" above the cylinder/head gasket interface, the pressure force will have to make two 90° turns to interact directly with the head gasket seal.

Might that increase head gasket reliability??

Pressure acts equally in all directions.

Slick

Dan1950 said:

With the stock piston compression height, the combustion chamber pressure works on the head gasket seal in a straight line around the perimeter of the combustion chamber. Since the unaltered piston crown of the set-up I hope to utilize will protrude well over .100" above the cylinder/head gasket interface, the pressure force will have to make two 90° turns to interact directly with the head gasket seal.

Might that increase head gasket reliability??

Click to expand...

Flame ring gaskets are 100% reliable in my experience... If you ensure scrupulous cleanliness, a little over torque on first assembly, and an anal retentive torquing procedure during the first 6-800 miles.

What static CR are you shooting for?

Dan1950 said:

Getting to the point where I will soon be able to do a clearance mock-up of my rotating assembly. I'm shooting for .040" quench height between my piston crown and head deck.

Rather than stacking up various thicknesses of gaskets, I would like to have the quench pad in the head deepened the necessary amount to achieve the desired quench height. Shouldn't need much more than about .010" removed.

Hoping to use the composite fire ring head gasket to prevent leaks.

Click to expand...

Rather than calculating squish (is that what you mean?) I would do a test assembly with pads of plasticine in the valve pockets and near the edges.
Carefully rotate the crank.
Remove the head and, using a scalpel (or very thin, sharp knife) cut the plasticine and carefully measure how close things came.
I think, with things like this, you can't beat the empirical method.
Cheers

My issue with Composite head gaskets is they need to be re-torqued a few times before they're fully settled, which makes it difficult to get an accurate squish clearance.
I still use them, but not on tunes motors.
Never had problems with copper head gaskets myself, and with JS Motorsport offering various thicknesses, it makes life simpler.

B+Bogus said:

My issue with Composite head gaskets is they need to be re-torqued a few times before they're fully settled, which makes it difficult to get an accurate squish clearance.
I still use them, but not on tunes motors.
Never had problems with copper head gaskets myself, and with JS Motorsport offering various thicknesses, it makes life simpler.

Click to expand...

Agreed about copper - but I would be confident that an old, used composite would work for the purposes of my suggestion in #7 above.

Dan1950 said:

I heard that the new gaskets have a thicker compressed height.

Click to expand...

The latest composite AN head gaskets are 1.00mm thick. Earlier gaskets were 0.75mm.

Dan1950 said:

With the stock piston compression height, the combustion chamber pressure works on the head gasket seal in a straight line around the perimeter of the combustion chamber. Since the unaltered piston crown of the set-up I hope to utilize will protrude well over .100" above the cylinder/head gasket interface, the pressure force will have to make two 90° turns to interact directly with the head gasket seal.

Might that increase head gasket reliability??

Click to expand...

The flame ring composite blew out.

I've run the .023" copper, with no failures 32,000 miles.
(Only a SLIGHT oil drool when my front studs won the tug of war in the aluminum threads in the head, and quit clamping properly.)

JMWO

texasSlick said:

Pressure acts equally in all directions.

Slick

Click to expand...

Pressure will be reduce momentarily if the volume of the fluid is restricted.

Fast Eddie said:

Flame ring gaskets are 100% reliable in my experience... If you ensure scrupulous cleanliness, a little over torque on first assembly, and an anal retentive torquing procedure during the first 6-800 miles.

What static CR are you shooting for?

Click to expand...

Approximately 10.1:1 static, 7.5:1 dynamic.

robs ss said:

Rather than calculating squish (is that what you mean?) I would do a test assembly with pads of plasticine in the valve pockets and near the edges.
Carefully rotate the crank.
Remove the head and, using a scalpel (or very thin, sharp knife) cut the plasticine and carefully measure how close things came.
I think, with things like this, you can't beat the empirical method.
Cheers

Click to expand...

I plan to do all that, I just want a starting point.

L.A.B. said:

The latest composite AN head gaskets are 1.00mm thick. Earlier gaskets were 0.75mm.

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

Motorcycle parts and spares for Norton motorbikes - Genuine Andover Norton Spare Parts - Andover Norton Motorcycles Parts - Original Andover Norton Parts

Motorcycle parts and spares for Andover Norton motorbikes: Andover Norton manufactures and supplies all Genuine Factory Spare Parts for Norton motorcycles built before 2002.

andover-norton.co.uk

Click to expand...

The existing head gasket measures .034" compressed.

Since the information about compressed composite gasket thickness does not exist on the pages LAB linked to, who has actually removed a newer used gasket recently and measured it?

I was hoping they were a little thinner like they used to be. Boo Hoo

A word of caution ref the RGM composite gasket. I recently fitted one, torqued the head correctly. Rode for about 20 miles and when things had cooled decided to check the torque of head fastenings. I wasn't expecting much to change after such a short run but was dismayed to find that all the fastenings were finger tight only! I emailed RGM to ask if they had heard of this before but have not had a reply. Have now replaced it with an AN gasket. Did a quick 10 miles run and everything tight as it should be.

Dan1950 said:

The existing head gasket measures .034" compressed.

Click to expand...

Schwany said:

Since the information about compressed composite gasket thickness does not exist on the pages LAB linked to, who has actually removed a newer used gasket recently and measured it?

I was hoping they were a little thinner like they used to be. Boo Hoo

Click to expand...

Since my compressed gasket is only a little over .005" under the 1mm spec of the newer gaskets, I am assuming that it is the newer thicker version. since I doubt that it grew .003" from the .75mm version.

Ordered these from JS Motorsport yesterday.






Andover Norton is dispatching my order today. (Placed the order yesterday evening)

Qty Part No Description Price Each Line Total VAT% Line VAT
1.000 06.0599 KICKSTARTER PINCH BOLT 3.95 3.95 0.00 0.00
6.000 06.0622 RUBBER MOUNTING 2.69 16.14 0.00 0.00
1.000 06.0759 GEARBOX SPROCKET 22T 5/8" x 3/8" 31.92 31.92 0.00 0.00
2.000 06.2412 EXHAUST LOCKRING TAB WASHER 1.95 3.90 0.00 0.00
2.000 06.3988 EXHAUST LOCKRING (CHROME - SHORT) 30.86 61.72 0.00 0.00
2.000 06.3995 SEAL WASHER (06.3253) (NMT2166) 0.80 1.60 0.00 0.00
2.000 06.4118 CRANKSHAFT MAIN BEARING (NM17822/4) 64.95 129.90 0.00 0.00
1.000 06.4285 BEARING SHELL SET (STD) (NM23255) 59.95 59.95 0.00 0.00

GASKET & SEAL KIT (FULL 850cc Mk1/2 COMPOSITE HEAD
GASKET)

1.000 06.5030 39.95 39.95 0.00 0.00
1.000 06.7094 CRANKSHAFT STUD/NUT KIT (750+850) 1972- 1974 36.95 36.95 0.00 0.00
1.000 06.7245 TOOL FOR PRIMARY CHAINCASE INSPECTION CAPS 5.38 5.38 0.00 0.00
1.000 06.7325 INTERMEDIATE SHAFT SUPPORT PLATE TOOL 21.20 21.20 0.00 0.00
4.000 06.7569 CRANKSHAFT SHIM .003" (NMT 2196A) 3.07 12.28 0.00 0.00
1.000 06.7689 CAMSHAFT CHAIN (NM17806) 11.90 11.90 0.00 0.00

IGNITION TIMING PLATE CHECK TOOL (COMMANDO 1969 TO
1974)

1.000 13.1769 7.40 7.40 0.00 0.00
1.000 13.1807 WOODRUFF KEY SET 8.97 8.97 0.00 0.00
DELIVERY DHL - Express WorldWide 53.66 0.00 0.00