Head Gasket Sizes

[gaillarry]

Reading the James and Cometic gasket catalogs I see head and base gaskets with " .30 " or ".40" sizing and some are " metal" or "teflon" and more with "fire ring".  I'm just looking to replace the base and head gaskets on my 86 FLHTC.   For the uninformed what does all this mean?

[ClassicRider2002]

Reading the James and Cometic gasket catalogs I see head and base gaskets with " .30 " or ".40" sizing and some are " metal" or "teflon" and more with "fire ring".  I'm just looking to replace the base and head gaskets on my 86 FLHTC.   For the uninformed what does all this mean?

gaillarry~~

.030 or .040 sizing references how "thick" the head gasket might come in....the .030 thousandths is "thinner" which allows more "compression" vs the .040 thousandths thickness for example.....basically this has to do with "squish" which allows one to create a bit more compression for your engine by using a 'less" thick gasket....

the base gaskets sometimes end up being an "o~ring" for example.....basically there isn't any "thickness" option for a base gasket unlike there is for your head gasket.

Regards,

"Classic"

[bobrk1]

the shop i deal with uses the cometic with good luck got them in my RK.

[rdkng]

Yes, its the thickness of the gasket, and I believe the measurement is
for when its compressed.. not out of the box.  There are many variations
amoung the major brands. James, Cometic, S&S, HD, and even HD SE.

There are also a lot of opinions on what is best.  i.e. a 'thin' headgasket
like a .030 cometic, but others will say mill heads or cylinders down and
go with a .045 head gaskets for the same resulting squish.   I'm no big
expert, but i think in general the thinner gaskets can give you closer tolerances, but
can also be less forgiving on leaks & clearances. 
rdkng   

[ClassicRider2002]

i think in general the thinner gaskets can give you closer tolerances, but can also be less forgiving on leaks & clearances. 

rdkng~~~

Interesting point.....sounds like using hylomar or aviation gasket cement would do the trick here if there is ever such a problem.....

Would enjoy reading more thoughts on the potential for a problem as you suggest the possiblity of......

Regards,

"Classic"

[Flat Dog]

I've had head gaskets blow either way-hylomar or no hylomar. If the mating surface is out of spec, no amount of goo is going to keep high pressure such as a compression stroke sealed up tightly. If it's not a pressurized mating surface, then goo may help unless the surfaces are constantly heat cycling, which most are.

[ClassicRider2002]

I've had head gaskets blow either way-hylomar or no hylomar. If the mating surface is out of spec, no amount of goo is going to keep high pressure such as a compression stroke sealed up tightly. If it's not a pressurized mating surface, then goo may help unless the surfaces are constantly heat cycling, which most are.

PhotoJohn~~~~
I am enjoying our discussions along the way here at HTT, respectfully however based upon your comment above I would direct anyone to the LINK below:

FXR RELATED TOPIC DISCUSSIONS  <~~~CLICK, VIEW, & READ

Indeed while this relates to FXR's.....if one were to direct their attention to the middle of the Index they will find 6 different Links to articles  relating to EVO Engines in general which of course in part discuss the use of "Hylomar" or "Aviation Gasket Cement" as excellent sources for head & rocker box gaskets for our evo engines in general......the authors I am quoting within these discussions are folks like AlphaSameul ie: Samuel, as well as JohnS_Rosamond_CA ie: JohnS who are quite emphatic about the solutions they have seen with these evo engines.....of course Samuel has passed on....but his reflections have always been worthy of following.....

I realize we all have our own individual experiences.....but as these "THREADS" become dated and people do their own searches I would hate to leave a doubt in anyone's mind about how to have the confidence that their evo engine with a certain amount of "goo" lol will absolutely have a positive result.....at least people with the topical discussions can read and judge for themselves.....

By the way I am not "jumping" you on this.....but merely trying to point out that the very 'essense" of the "goo" solution was and actually has been held in high regard.....and from a personal experience, I have had two "blow outs" on my 1999 FXR2, both occuring right after I purchased my 1999 FXR2 in May of 05, the first problem was "authored" obviously from the lack of use by the previous Owner of the bike.....and sitting in a garage unheated thus seals and gaskets dried up pretty well....the next was when I attempted to fix the problems from the dry gaskets and used James Gaskets where I should have stuck with the OEM Gaskets for the rocker boxes and then used Hylomar in a certain locations of the lower Rocker one piece gasket....I know the subject here is about "head gaskets" and within the topics I am referencing above such discussions are inclusive of "head" gaskets in particular.  I hope people will feel inclined to take the time to read some of those articles.....regardless of whether they own an FXR, as they relate to an evo engine....   

Regards,

"Classic"

[gaillarry]

I have read all these articles and very impressed with the comments from JohnS, thats why I will
use holymar or aviation cement.

[Flat Dog]

Oh, I absolutely love brown gasket goo Classic-been using it for 4 decades in various forms. I just didn't want inexperienced people to think that gasket sealer is the duct tape of the metal surfaces world.

I am a firm believer that adding the stuff to an already good mating surface is nothing more than added protection and a good idea...it's just not a cure all for warped surfaces under pressure. Heck-most aerospace employees know that adhesives and carbon weave/kevlar materials are stronger than steel, welding, bolts, etc. I worked for a mil contractor for 9 years, and saw lots of brown sticky goo added to many critical applications.

Thanks for saving all of those great posts classic-very helpful!

[ClassicRider2002]

Oh, I absolutely love brown gasket goo Classic-been using it for 4 decades in various forms. I just didn't want inexperienced people to think that gasket sealer is the duct tape of the metal surfaces world. 

Photo John~~~

Ahhhhh but it is.....life is such a simple place.....

Regards,

"Classic"