• Hi Guest! Being a Paying Supporter is NOT a requirement to participate at BCF. However, subscribing will help ensure we can continue to serve the LBC community for years to come. If you enjoy BCF and find our forum a useful resource...Please consider supporting us by **Upgrading**
    (PS: Subscribers don't see this banner)
Tips
Tips

TR2/3/3A Figure of Eight Gasket Compression - Copper vs. Steel

Joel M

Senior Member
Country flag
Offline
I am currently making preparations for engine assembly within the next 3-4 weeks, and am trying to decide between steel and copper Fo8 gaskets. I understand the corrosion aspect, but the copper gaskets I have are 0.003" thicker than the steel ones (0.018" compared to 0.015"). Are these equivalent thicknesses due to copper being a softer metal that will compress more once the head is properly torqued? If not, I believe the extra 3-mils will force me to take down the liners some, and I'm not sure going with copper is worth the extra step. Also, I assume that two sets of Fo8 gaskets are required - one for checking protrusion after torquing and removing the head, and the second for final assembly. Is this correct?

Joel
 

CJD

Yoda
Country flag
Offline
It's generally accepted that the copper are better. That said, I do not think they are enough better to warrant skimming your liners. If you would need to skim, and you cannot obtain the proper size copper, then use the steel with Wellseal (or other favorite sealant) and never look back!
 

DavidApp

Yoda
Gold
Country flag
Offline
You should only need one set unless you find the liners either protrude too much or there is not enough protrusion. Then you would have to remove the liners to rectify the problem possible damaging the Fo8 gaskets.

Remember to check the protrusion on both left and right sides of the cylinder. The protrusion may be different.

David
 

glemon

Yoda
Country flag
Offline
I think the copper will compress more, that is just an amateur seat of the pants guess. Then again I rebuilt my first TR engine without the aid of any precise measuring tools. The liners portruded "a tiny bit" over the plane of the block, pretty sure the gaskets were copper. No problem with the liner seals or head gasket many many years on.
 
Last edited:

TomMull

Luke Skywalker
Silver
Country flag
Offline
I pretty much agree with glemon although I think the book says .003 to .005. I measure with a straight edge and a feeler gauge and have had no issues even with a bit less. I've also had several where the little bit went to nothing but never had one that was too high. The low ones were fixed with thicker FO8s but I don't know if those are still easily available.
For what it's worth, I've also checked them with copper FO8s before and after I torqued the head, just to see if they did indeed compress. I could not discern any change albeit with the feeler gauge and straight edge.
The steel ones started to come with the liner kits at some point but I never used them.
Tom
Tom
 

CJD

Yoda
Country flag
Offline
I know I tend to be a bit anal...but some anal tips:

Due to irregularities on the block and liners, I don't feel the first install tells you anything. I always buy 2 sets of gaskets, and do a mock build using the first set. After torqueing the head and later removing, I can see if/or how much the F08 will compress. I then take the liner measurements and adjust the F08 thickness if I need to.

Wellseal was designed to keep the liners sealed in Mustang Merlins with 40# of boost...so I figure it'll work on my Triumph. That's what I use for the final build. Once again, if you goop the F08's before you measure the liners, it'll affect your measurement too.

Anal enough??
 

Sarastro

Obi Wan
Gold
Country flag
Offline
Neither the copper nor the steel gaskets actually compress to any measurable degree, if you mean in the standard sense, i.e., elastically. If they seem to compress, it's probably because of the sealer getting squooshed out from under them, burrs along the edges getting flattened, or irregularities getting flattened. It's a good idea, I think, to deburr the gaskets and make sure they are flat. Also make sure that NO debris gets under them.

In the engine I'm currently working on, I first trial-fit the gaskets, got the protrusions right, and marked the cylinders' and gaskets' positions. I then disassembled them, added sealer, and reinstalled them. I found it necessary to tap the cylinders into place with a hammer and wood block, to squeeze all the sealer out and to have the same protrusions as when I trial-fit the cylinders. You want to end up with mostly metal-to-metal contact, and sealer just filling irregularities. You don't want the cylinder floating on a layer of sealer. If you obtain the same protrusions with sealer as in the trial fit, I think you can be confident that you have metal-to-metal contact and the protrusions will not change when you torque the head.

Here is a detailed description: https://www.nonlintec.com/tr4a/engine2/#cylinders
 

sp53

Yoda
Country flag
Offline
I had a set leak once at least I think it was F8 gasket, but cannot be sure exactly where the leak happened. I fixed it with block sealer. I also seem to remember on the older gasket kits the figure 8s were maybe iron steel alloy gasket with this white coating over them, like a plastic or something. My concern after I had this leak was that the down time from taking the temporary hold downs off the block and putting the head on and torquing the head down something happened. Perhaps the sleeves separated from the F8 or perhaps the permatex non- hardening gasket material I used never bonded correctly.


Anyways, I took this story to a machinist whom I thought was the best. His suggestion was to take the gaskets and put about 3 to 4 heavy coats of silver spray paint on the figure 8s and put them in that way because the paint never really dries well and lays flat and would give me time to work. I did that, but I have not run this engine for more than half hour, but so far so good. Moreover, I am always surprised how tight the sleeves go in and how small the area for sealing is, so whatever is used on the gaskets should be thought out. In addition, I figured when the engines were first built, they put the head on within an hour or so, so if that is the case that would eliminate what I was concerned about with a gasket sealer not bonding, plus it is my understanding they used the weelseal product.
 
OP
J

Joel M

Senior Member
Country flag
Offline
Thank you all for the advice. I think I will first try the copper gaskets and gauge the protrusion. If out of spec, I will try the steel. Not sure where to source 15-mil copper gaskets. The only ones I've seen are 18.

Joel
 
Similar threads
Thread starter Title Forum Replies Date
Hamish Racing TR2/3/3A Fast Road TR3a on figure of 8 sprint track - UK Triumph 10
Got_All_4 TR5/TR250 Trying to figure out rear transmission mount with a J type tranny Triumph 9
Jim_Gruber Need help to figure out an easy solution for this one. Spridgets 13
2wrench TR6 Horny car just won't quit. On top of that, likes diesel. Go figure. Think mechanics Triumph 9
Jer when something doesnt make sense... and you finally figure out why ! Spridgets 4
P TR2/3/3A Figure 8 gaskets at bottom of liners Triumph 4
2billydavies TR2/3/3A question about Figure of 8 installation Triumph 9
S TR2/3/3A Figure 8 gaskets Triumph 17
F White smoke and I cant figure it out. Spridgets 17
bighealeysource Can't figure out why engine is missing on BN2 Austin Healey 6
B MGB Go figure! lucky day today! MG 3
K Figure of 8 Gaskets for Wet Liner Engine? Triumph 5
M can not figure out search FORUM Help 1
KVH Figure 8 Gasket Info Triumph 0
KVH Revelation Re Those Figure 8 Sleeve Gaskets Triumph 8
KVH Figure 8 Gaskets Below the Sleeves Triumph 4
newmexTR3 How do you figure out a cam's valve clearance Triumph 2
regularman Still trying to figure this overheating thing out. Spridgets 35
Luke_Healey How do I figure out what kind of brake fluid? Spridgets 24
PATR8 Wedge TRy to figure this TR7 out Triumph 10
jdubois Ok, the Triumph guys couldn't figure this out... MG 17
regularman This here is what I figure I am going to do Spridgets 12
Rob_P Trying to figure out wgich carpet piece goes where MG 7
KVH Those Figure 8 Gaskets Triumph 1
jaybird Figure this one out please! Disappearing gasoline MG 37
M If I could just figure a way...... Austin Healey 2
R Tracking down my dads old Austin Eight Other British Cars 3
K 1937 Daimler Light Straight Eight Other British Cars 4
R eight scratches in a windshielWindshield scratches Other Cars 8
bcliff Fifteen miles at eight degrees equals... Triumph 7
bcliff Fifteen miles at eight degrees equals... MG 24
bcliff Fifteen miles at eight degrees equals.... Other British Cars 18
Steve Eight sexiest cars.....on MSN.com this morning Other Cars 41
Csarneson Head Gasket Seal Austin Healey 6
Tr3aguy TR2/3/3A Gasket part way off Triumph 10
B Bonnet hinge gasket Spridgets 10
nichola TR6 Recommendation for tail lamp to body gasket Triumph 16
R Cylinder head gasket BJ8 Austin Healey 32
C Wanted Ford Kent Pre-Cross Flow Gasket Other British Classifieds 3
B TR4/4A Head gasket won't lay flat Triumph 13
T TR6 TR6 Carb Gasket Sealing Triumph 1
Michael Oritt Manifold Gasket Dressing/Sealant Recommendations Austin Healey 6
K Gearbox Throw-out pin and gasket question Austin Healey 8
GeorgeC Intake / exhaust manifold gasket install goop? Spridgets 2
D TR2/3/3A OD cover plate gasket sealer. Triumph 17
F Sump Gasket Question Austin Healey 15
AUSMHLY Gasket, Inlet Manifold to Exhaust Manifold BJ8 Austin Healey 8
D TR2/3/3A Hints on sealing the sump gasket. Triumph 28
F Heater valve/tap gasket- Install dry? Austin Healey 10
steveg Strange gasket pieces Austin Healey 5

Similar threads

Top