Funny head gasket

OVERLORD Mon Jun 20, 2016 11:39 am

Yesterday, I was checking my OS Max 19 RC Marine and on the compression stroke, I heard a hissing sound, audible on the outside of the engine. It didn't seem to come from the carb or from blow by resonating in the exhaust port. I removed the head and discovered a paper gasket, well impregnated by castor. I've seen wooden pistons, but never a paper head gasket!! I suppose it would have worked, but not for a long time. Luckily, the person I bought the engine from, included the aero head and I found the head gasket still on there.

Both combustion chambres have the same shape but on the standard head, the plug hole is off centre as on the 15 III. On the marine head, the plug hole is in the centre.

After reassembling, I mounted the #702 strap-on muffler.

Funny head gasket Imgp3510

Surfer_kris Mon Jun 20, 2016 2:58 pm

Paper gaskets where common at that time, webra had that in their engines too as I remember it. Works fine until the take them appart and need new gaskets for the assembly...

OVERLORD Tue Jun 21, 2016 4:43 am

Kris, I had a look at some period articles on Sceptre-Flight and Webra used graphite asbestos gaskets which sit in a recess in the head. On other Webras, there seems to be no gasket at all (dixit P. Chinn). Were they the only ones to use such head gaskets? On the OS 19, it was definitely not the correct one.

Funny head gasket Kit_os10

Surfer_kris Tue Jun 21, 2016 6:09 am

From memory I think the AM 1.5 also used a paper gasket for the head and below the cylinder too, most likely asbestos containing to stand the heat.

Others like the Veco .19 didn't have any head gasket, but used a paper gasket on the back of the crankcase.

Oldenginerod Tue Jun 21, 2016 6:26 am

All the Wen Mac .049s, up until those fitted with the newer style cylinder and glow head, used a paper head gasket inside the cylinder muff, sealing against the upper edge of the cylinder. These seem to be very reliable but will obviously deteriorate with age and frequency of disturbance.

gcb Wed Jun 22, 2016 11:24 am

OVERLORD wrote: ...Both combustion chambres have the same shape but on the standard head, the plug hole is off centre as on the 15 III. On the marine head, the plug hole is in the centre.

It has been awhile since I looked but I believe that my MAX-III .15's all have centered plugs. Is this a change that was incorporated on the later ones?

As others have mentioned, the fiber gaskets were common and the "Perfect" company used to sell packaged pieces of head gasket material so you could cut your own replacements.

George

OVERLORD Wed Jun 22, 2016 12:17 pm

gcb wrote:
OVERLORD wrote: ...Both combustion chambres have the same shape but on the standard head, the plug hole is off centre as on the 15 III. On the marine head, the plug hole is in the centre.

It has been awhile since I looked but I believe that my MAX-III .15's all have centered plugs. Is this a change that was incorporated on the later ones?

As others have mentioned, the fiber gaskets were common and the "Perfect" company used to sell packaged pieces of head gasket material so you could cut your own replacements.

George

George, my 3 .15 III's all have a off centre plug hole. Could yours be swapped with a head of the later OS Max 15? The bolt configuration looks the same.

Funny head gasket Imgp0110

gcb Wed Jun 22, 2016 7:09 pm

OVERLORD wrote:
George, my 3 .15 III's all have a off centre plug hole. Could yours be swapped with a head of the later OS Max 15? The bolt configuration looks the same.

Curiosity got the best of me so I pulled out a couple of my .15 III's and you are correct, their plugs are off center...just something I had forgotten or never noticed.

George

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