Every headgasket needs a properly machined head and deck surface.
Break in is a crutch for poor machining, and even break in won't help it!
A dealer, factory parts, and a GOOD race machine shop are miles apart.
We have built hundreds of HP street, and race engines to very tight tolerances with very expensive equipment, and zero break in. The tolerances, finish, and quality of parts is a major difference between race parts and machining and factory assembly line engines.
Done properly, no break in is needed.
Cometic and other seriously HP gaskets require the block AND heads be surfaced with CBN diamond tooled equipment, only, read the instructions, anything else is a gamble, or luck, nothing more.
The pic is of a 572", hi helix 14-71 blown, Brodix headed, water to air intercooled boat motor. It made 1268 HP on pump gas, WITHOUT the nitrous, at 11.5 lbs boost. There was another 400 HP of squeeze on it too. On pump gas.
The first outing was to Havasu where it ran over 126 MPH without the bottle, for 11 miles. Then the boost was cranked up, and on 100VP, it ran over 150 on the way back. Without the "bottle." That was its "break in." Nobody wanted to drive it top speed on the bottle, just get "there" quicker.
It was sold after 14 years with the same motor in it, then the new owner leaned it out (he said he was a better tuner than us) and burnt a piston a few years later. It got a new set of pistons, rings, and a hone, and is still running (our tune again.)
I've never seen a factory machined motor and parts win a NASCAR or NHRA race, just saying.
TIMINATOR
Of course get rid of the "O" rings to.
