103mm head gasket with o-ring head
12-13-2017, 12:36 AM
#1
Instructor
Thread Starter
103mm head gasket with o-ring head
I am in the the process of building a 2.85l hybrid engine and have a bore of 4.030 or approximately 102.3mm. I also have a rebuilt head with a steel wire o-ring setup I am planning to use.
My question is if there is a widefire type fiber gasket available for the 8v head in 103mm bore and 0.040” compressed height? I talked with Mike Lindsey and he said an MLS gasket is not recommended with o-rings. I also considered a copper gasket but am concerned about water sealing and am having a hard time finding one thin enough. SCE makes one but it is 0.060 thick if I remember correctly. What suggesti9ns or sources can you offer?
Thanks,
Steven
My question is if there is a widefire type fiber gasket available for the 8v head in 103mm bore and 0.040” compressed height? I talked with Mike Lindsey and he said an MLS gasket is not recommended with o-rings. I also considered a copper gasket but am concerned about water sealing and am having a hard time finding one thin enough. SCE makes one but it is 0.060 thick if I remember correctly. What suggesti9ns or sources can you offer?
Thanks,
Steven
12-14-2017, 09:54 AM
#3
Instructor
Thread Starter
I spoke with the machine shop and came up with a choice of solutions.
I can either run the stainless o-ring but switch to a copper gasket as offered by sce and coat with yamabond for water sealing and follow torque idea per Chris White in an earlier thread to torque to 40 ft/lbs and then leave overnight and then loosen and began normal torque process. My main concern with this is a possibility of water leakage long term on a street engine and the fact the sce gasket fire hole has a spacing of 102 mm while my bore is actually 102.3 mm but piston is .032” below deck. This is also why I am concerned to just run the factory widefire gasket since the fire ring will have a small protrusion of about 0.015mm into the bore.
Currently preferred option is to remove the stainless orings and replace with a similar sized copper wire. I found 18awg size pure copper wire to be about 0.040” and is soft enough to fully compress using a Cometic mls 103mm gasket. I think I would feel more comfortable about this than using an epoxy as it can be reversed if needed and is a solid item rather than a liquid epoxy with a possible air void in that area. I am planning to do some more measuring and may even use a 20 Awg wire to go further in the o ring to sit more flush with the deck. The current ring protrudes 0.06” above the deck.
Comments and thoughts are definitely welcome.
I can either run the stainless o-ring but switch to a copper gasket as offered by sce and coat with yamabond for water sealing and follow torque idea per Chris White in an earlier thread to torque to 40 ft/lbs and then leave overnight and then loosen and began normal torque process. My main concern with this is a possibility of water leakage long term on a street engine and the fact the sce gasket fire hole has a spacing of 102 mm while my bore is actually 102.3 mm but piston is .032” below deck. This is also why I am concerned to just run the factory widefire gasket since the fire ring will have a small protrusion of about 0.015mm into the bore.
Currently preferred option is to remove the stainless orings and replace with a similar sized copper wire. I found 18awg size pure copper wire to be about 0.040” and is soft enough to fully compress using a Cometic mls 103mm gasket. I think I would feel more comfortable about this than using an epoxy as it can be reversed if needed and is a solid item rather than a liquid epoxy with a possible air void in that area. I am planning to do some more measuring and may even use a 20 Awg wire to go further in the o ring to sit more flush with the deck. The current ring protrudes 0.06” above the deck.
Comments and thoughts are definitely welcome.
12-14-2017, 10:30 PM
#4
Instructor
Thread Starter
Thanks Bob for the suggestion. I pulled the end of one of the o-rings out to measure and it came out to 0.041” which is equivalent to 18 Awg. I ordered some pure copper 18 Awg wire for jewelry to replace the o rings and plan to go with the cometic mls. Should arrive this weekend. It is dead soft and should do the same job of filling the grooves for the orings.
12-16-2017, 11:25 PM
#6
Rennlist Member
FWIW I'll chime in with my 2 cents. A MLS gasket with an O-ringed head is a guaranteed leaker. Yamabond which I have experience with from way back in the day is good stuff in the right place but is not going to work on a headgasket. The issue here is the O-ring. Pull the O-ring and assuming the block and head surfaces are acceptable for a MLS gasket I would suggest ether copper coat spray or IMO better yet Hylomar spray.