Head gasket

[Nikhil Bhale]

As a Marine Engineer who has worked on many big engines of 25000 bhp and more I have seen engines without a head gasket or gaskets for fuel valves (injector).
The seating areas are lapped with special tools provided and parts are assembled without any gasket, liquid or solid.
The cylinder head nuts are hydraulic tightened by stretching the bolt with a special puller and then tightening the nut by hand. Nuts are round with drilled holes around the circumference to apply some torque by a small 6" tommy bar.

 

[minh-thanh]

As a Marine Engineer who has worked on many big engines of 25000 bhp and more I have seen engines without a head gasket or gaskets for fuel valves (injector).
The seating areas are lapped with special tools provided and parts are assembled without any gasket, liquid or solid.
The cylinder head nuts are hydraulic tightened by stretching the bolt with a special puller and then tightening the nut by hand. Nuts are round with drilled holes around the circumference to apply some torque by a small 6" tommy bar.

View attachment 144413

But no one has that machine
Homemade engine just need flat surface and head gasket is good enough

Hi Gordon
I don't know if there is enough room to drill more holes for bolts?
If you still have it, you can do it like this
Whatever the solution, the surface must be flat

 

[Gordon]

I am still working on this from time to time until I get frustrated and move on to something else. My solution is ultimately going to be adding two more head bolts in the valve area as you suggest.

I have been trying to work out an ignition system to fire both cylinders using a wasted spark but I have reached the conclusion that I either need two ignition modules with separate input signals or a distributor. Two magnets 50° apart makes one cylinder fire at the correct time and the other cylinder fire part way into the compression cycle. The engine kind of tries to run even with the leaking head but it is basically just running on one cylinder.

I am going to have to learn how to concentrate on one problem at a time instead of moving from one frustration to another frustration.

 

[minh-thanh]

Gordon !
.... I haven't made that engine yet so with my little experience...
If you have the last option of using bolts then do it , it will save your time and effort ... . That's also my choice in this case.

 

[kf2qd]

2 bolts are not going to allow much pressure for sealing.and that intake port close to the edge doesn't make it any easier.

 

[Gordon]

I have placed two additional screws in the valve area and I no longer have a leak at the head when using a teflon gasket. Still having a problem getting enough compression to run even using O rings. Valves are sealing and there does not seem to be leakage around the piston but still not enough compression to run. Engine is 3/4 bore x 1" stroke. Obviously I am missing something.

 

[minh-thanh]

I have placed two additional screws in the valve area and I no longer have a leak at the head when using a teflon gasket. Still having a problem getting enough compression to run even using O rings. Valves are sealing and there does not seem to be leakage around the piston but still not enough compression to run. Engine is 3/4 bore x 1" stroke. Obviously I am missing something.

Not enough compression or your engine can't draw fuel ?

https://www.homemodelenginemachinist.com/threads/make-break-wont-run.34793/

 

[Nikhil Bhale]

Hi Gordon,

What engine is this? Is it your own design or is it of some proven design?
If the clearance volume is high you will not get a good compression even if there are no leakages. Compression ratio is ratio of clearance volume to swept volume.
Using a thick head gasket will increase the clearance volume reducing compression.

Regards
Nikhil

 

[Peter Twissell]

I assume you meant to say compression is the ratio of (swept volume PLUS clearance volume) / clearance volume...

 

[Nikhil Bhale]

I assume you meant to say compression is the ratio of (swept volume PLUS clearance volume) / clearance volume...

Yes you are right. I should have said ratio of total volume (Vs +Vc) to clearance volume Vc.

regards
Nikhil

 

[DKGrimm]

Here is a picture of an original design that I've been poking at for over seven years. I won't bore anyone with a list of problems already solved or problems not solved, getting the head gasket to seal is number 2 on my list right now. I've had the best luck with a 0.030" fiber head gasket, but it certainly does not like it when I try to re-use one a second time. It's 3/4" bore, with seventeen headbolts, and water passages, so it's a bunch of work to cut one out of stock by hand. I have been intrigued by talk of laser cutting a gasket, and have gone so far as to look a little bit at getting a laser engraving machine or some such that could do that from, say, a DXF file. Problem is I don't have enough time to spend on the hobbies I already have. Setting up and accumulating software for a machine is just a bridge too far. So my question is: does anyone already do gaskets in quantities of half a dozen gaskets or so (for cash)? This is not an emergency, but the Black Hills engine show is in September.

Regards,

Don

 

[Gordon]

I have been very happy with my Silhouette Portrait cutter. You have to make a DXF drawing and the gasket does not come out to the correct size so you have to rescale it. There may be a way to avoid this but for my use I have not spent the time to investigate it. Cuts holes as small as 1/16" dia.

https://www.amazon.com/Silhouette-A...mzn1.fos.18ed3cb5-28d5-4975-8bc7-93deae8f9840

 

[Rocket Man]

I make gaskets for my model airplane engines. I made a punch die set to hand punch gaskets quick and easy from copper or aluminum. First I punch out a .875" diameter slug. Slug goes into another die to punch a .750 diameter hole in the center of the slug. My metal thickness is .020" or thicker .030" if I want. The finished gasket .875" OD and .750" ID. I can hit the punch with a hammer or squeeze the punch die set in a vise.

 

[peterl95124]

none of my engines have ever had gaskets. lap the top of the block and/or the tops of the cylinder liners flat, lap the bottom of the head flat, assemble, run. never had a problem. one time when I would have had to lap down 5 cylinder liners to get to the level of the 1 low one to get them all flat at the same time I instead used form-a-gasket around the low cylinder liner, diluted 1:1 with ethanol so it can be painted on in a very thin uniform coating and wait for the alcohol to evaporate before assembly, again never had a problem.

if you think you're having compression problems try putting a few drops of oil into the cylinder, this will temporarily seal the rings and the valves and any head/block joint leaks, if it runs until the oil burns away (or the spark plug fouls with oil) then yes you might have a compression problem.

in my experience there are a lot more ways to screw up valves and rings than head/block interfaces, mostly I learned the hard way. YMMV, let us know what works for you, then I might learn something important the easy way for once !

 

[awake]

Here is a picture of an original design that I've been poking at for over seven years. I won't bore anyone with a list of problems already solved or problems not solved, getting the head gasket to seal is number 2 on my list right now. I've had the best luck with a 0.030" fiber head gasket, but it certainly does not like it when I try to re-use one a second time. It's 3/4" bore, with seventeen headbolts, and water passages, so it's a bunch of work to cut one out of stock by hand. I have been intrigued by talk of laser cutting a gasket, and have gone so far as to look a little bit at getting a laser engraving machine or some such that could do that from, say, a DXF file. Problem is I don't have enough time to spend on the hobbies I already have. Setting up and accumulating software for a machine is just a bridge too far. So my question is: does anyone already do gaskets in quantities of half a dozen gaskets or so (for cash)? This is not an emergency, but the Black Hills engine show is in September.

Regards,

Don

Don, what is the overall size of the gasket? I'm willing to take a try at it if it will fit within my laser cutter (max size is around 8" x 12").

 

[DKGrimm]

I have been very happy with my Silhouette Portrait cutter.

Interesting suggestion. I looked it up on the internet. Can a knife really cut a 0.0625 hole cleanly through 0.030 gasket material?

 

[DKGrimm]

Don, what is the overall size of the gasket? I'm willing to take a try at it if it will fit within my laser cutter (max size is around 8" x 12").

Andy -

Here's a drawing. It's around 1-3/8" x 5". I can provide gasket material -- 1/32" stock from the local auto parts store. Send me a message off line if you want to discuss some more.

Don

 

[DKGrimm]

none of my engines have ever had gaskets. lap the top of the block and/or the tops of the cylinder liners flat, lap the bottom of the head flat, assemble, run. never had a problem. one time when I would have had to lap down 5 cylinder liners to get to the level of the 1 low one to get them all flat at the same time I instead used form-a-gasket around the low cylinder liner, diluted 1:1 with ethanol so it can be painted on in a very thin uniform coating and wait for the alcohol to evaporate before assembly, again never had a problem.

I looked hard at that, Peter. Sounds like a good solution, but I've got wet sleeves about 0.001 to 0.002 proud of the block that have to seal compression in the cylinder and also seal coolant from the block, so I chickened out. Your suggestion of thinned form-a-gasket might be the answer. You got me thinking.

Don

 

[DKGrimm]

I make gaskets for my model airplane engines. I made a punch die set to hand punch gaskets quick and easy from copper or aluminum. First I punch out a .875" diameter slug. Slug goes into another die to punch a .750 diameter hole in the center of the slug. My metal thickness is .020" or thicker .030" if I want. The finished gasket .875" OD and .750" ID. I can hit the punch with a hammer or squeeze the punch die set in a vise.

How do you do holes for hold-down bolts?

Don

 

[TimTaylor]

Interesting suggestion. I looked it up on the internet. Can a knife really cut a 0.0625 hole cleanly through 0.030 gasket material?

Another option - do you know anyone with a laser cutter/engraver? A good diode laser should easily cut fiber gasket material, and can do so with high accuracy, typically approaching 0.1mm or better.