• 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)

Tolerance for head gasket

Susan Lybolt

New rebuilt over heated. I have .02 on the head and .02 also on the block. Do I need to machine the head before refitting the head gasket?

Legal Bill

Jedi Knight
I assume you measured this with a straight edge and a feeler gauge? .02 is 20 thousandths. What I am reading is that combined you have a 40 thousandths gap between head and block. Is that correct? I'm pretty sure the head gasket cannot tolerate a .02 gap. I'm positive it cannot tolerate a .04 gap.


Great Pumpkin
Country flag
0.02 Hmmm
Weren't the surfaces machined as part of the rebuild ??


Great Pumpkin
Country flag
They were good until I used the wrong radiator cap. Short stem, lost antifreeze. Temp off the gage. You could say I red lined it.

Well the simplest thing to do is resurface the head.


Jedi Trainee
Country flag
Susan can you confirm that both the block and head are 0.020" out of flat or did you mean 0.002" ?
At 0.002" you cou​ld assemble as is.
If you really are 0.020" out, the block will require decking at a minimum. More importantly it should be checked in EVERY dimension to make sure cylinders aren't out of round and the block is not twisted.
If you severely overheated, good chance your rings are done. Reusing them may result in excessive oil consumption and/or blowby.
I would not recommend surfacing the head to eliminate 0.020" of bowing. You will end up with additional problems such as differences in combustion chamber volume that will raise compression in cylinders where the most material is removed. There are specialist companies that "might" be able to straighten that successfully.
Do it correctly now. You will be better off in the long run.

Susan Lybolt

The head and block were measured with a levelometer and feeler gauge. They were .002 in different areas of the head and block. not .02.


Great Pumpkin
Country flag
The head and block were measured with a levelometer and feeler gauge. They were .002 in different areas of the head and block. not .02.

I figured that was the case as at 40 thousandths there would have been no argument.
Still the simplest thing to do is resurface the head.


Darth Vader
Country flag
Susan, get a hold of some of the companies that actually make head gaskets. There are many American performance car companies that might have a pattern for the Healey. They make many types of gaskets that can compensate for irregularities. I don't think .002" is too much to compensate for. Dave.
Similar threads
Thread starter Title Forum Replies Date
W Brake Drum Tolerance ? Austin Healey 2
CCURTISS Wheel True - Tolerance Specification Restoration & Tools 1
M Tiny Tears in Top Test Tim's Tolerance Spridgets 5
drooartz Hose from water pump to head, remove water pump? Spridgets 12
F Wanted TR3A control head parts (trafficator) Triumph Classifieds 1
Csarneson Head Gasket Seal Austin Healey 6
71TR6 TR2/3/3A Control Head horn contact Triumph 7
R TR2/3/3A Cylinder head threaded plub Triumph 6
Lin Another Trafficator/Control Head Question Austin Healey 10
R Cylinder head gasket BJ8 Austin Healey 32
M Alloy cylinder head Austin Healey 5
HealeyRick For Sale Bare 29F Block, Cylinder Head and Manifold Austin Healey Classifieds 2
B General Tech Cylinder head costs MG 7
B TR4/4A Head gasket won't lay flat Triumph 13
HighAltitudeTR3 TR2/3/3A Aluminum Plug in Head Triumph 16
J For Sale TR 2, TR 3 TR 4 cylinder head Triumph Classifieds 6
B TR2/3/3A Control Head/Stator tube orientation Triumph 8
Mickey Richaud TR4/4A TR4 Head Needed Triumph 4
J TR2/3/3A TR 4A cylinder head on TR 3 engine Triumph 15
K TR2/3/3A Turn signal and control head memory refresh..... Triumph 9
K TR2/3/3A Turn Signal Control Head Alignment Again Triumph 1
S TR2/3/3A Horn not working unless I rotate the control head Triumph 6
K TR2/3/3A The 3 Steering Wheel "Grub Screws" and the Control Head. Triumph 2
T TR2/3/3A Is it possible to buy stronger springs for turn signal lever in control head? Triumph 14
T TR2/3/3A Questions on TR3A steering control head refresh Triumph 34
J TR2/3/3A Head Torque - Wet or Dry Triumph 6
Michael Oritt Head gasket question Austin Healey 17
banjojambo TR2/3/3A TR3A Re-torquing Head Nuts Triumph 7
Boink Rolls-Royce head replacement thread... Other British Cars 0
Got_All_4 TR6 Is this head toast or worth fixing Triumph 3
C TR4/4A TR4 coolant leak through aluminum plug in top side of head Triumph 6
G TR2/3/3A Fitting the Control Head - Telescoping [Adjustable] Wheel Triumph 20
6 1275 Head to block dowel pins Spridgets 10
Got_All_4 TR6 Do these numbers on the head mean anything? Triumph 6
Got_All_4 General TR Payen brand head gasket sets what's the difference Triumph 10
K Correct key head shape. Austin Healey 1
B 1500 head studs Spridgets 3
K TR2/3/3A Plug Weld CyL Head Triumph 10
Marvin Gruber TR4/4A TR3/4 head thickness Triumph 7
J TR4/4A Head leaking water Triumph 14
Drone Dog BT7 head manifold studs Austin Healey 7
P TR2/3/3A TR3A Steering Control Head Harness Triumph 7
R TR2/3/3A New Control head wiring - Moss purchase Triumph 1
M TR2/3/3A Tr3 Head Rebuild Triumph 3
Drone Dog bt7 head surprise Austin Healey 7
Simmo TR2/3/3A Head Gasket Triumph 4
K Wanted 100-6 exhaust manifold for two port head Austin Healey Classifieds 0
KVH General Tech Head Gasket Triumph 10
BN6_2197 Head Protection of Legroom Austin Healey 9
Bob_Spidell Re-torquing Head Nuts Austin Healey 4

Similar threads