Gee, the only reason I use steel gaskets is that the composite ones
seem to suck. they don't have good enough fire rings, and I've had
way too many blow on me. the steel gaskets hold up better, as long as
they are copper ringed. I never worried about the C/R.
If you have big intake valves you can't do anything to the composite
gaskets to unshroud the valve. anywhere that the gasket protrudes
into the combustion chamber melts away and then the hot gasses tunnel
through the composite.
I also like the solid copper gaskets, though I had one give out this
year. If I could get a composite gasket with a steel fire ring like
you get for any import engine then I'd never buy another shim steel
one--but all we can get is these fluffy copper clad things. You have
to torque and retorque them, and your torque always feels kind of iffy.
On Jun 7, 2006, at 5:08 PM, Jack W. Drews wrote:
> One man's opinion:
>
> Most of the time the steel shim gaskets will not work with variations
> this great. TOn the other hand, the stock sandwich gasket will
> usually tolerate variations of this size and will seal.
>
> Some owners really want to use the steel shim gasket just to get the
> increase in compression ratio. But, consider the fact that the stock
> sandwich gasket compresses to maybe .050, the steel shim gasket
> compresses to maybe .025, so you can get the same compression ratio
> increase by just milling the head another .025.
>
> There is another consideration as well, and that is in regard to the
> hp increase you get by increasing compression ratio with no other
> changes. Changing from a .050 gasket to a .025 gasket will increase
> your compression ratio by about 0.7:1 -- that is, it will increase a
> 10:1 CR engine to about 10.7:1. How many hp is that worth? Well, the
> generally accepted relationship is that each one point on compression
> ratio is worth about 3% hp increase (If there are no other changes
> made). Therefore, if you have a 150 hp engine, that CR change will
> yield about 4 hp. That's nothing to sneeze at, but most of us TR
> drivers can't feel the difference that four hp makes.
>
> Along with that, I've found that some TR engines kind of "max out" in
> the compression ratio vs. hp trade-off. On some engines, if you can
> run 11.5:1 CR and use 32 deg ignition advance without detonation,
> upping the CR to 12.5 will force you to reduce the ignition advance
> several degrees to avoid detonation. My experience with chassis dyno
> numbers is that being able to increase ignition advance has a pretty
> significant effect on hp and torque -- therefore, in some engines,
> you end up with the same hp either way.
>
> There are other reasons to use a steel shim gasket for the folks who
> want to make some more changes to the liner tops to get more flow,
> but that is a separate subject.
>
>
> At 06:11 PM 6/7/2006, you wrote:
>> Amici,
>>
>> A fellow FOT'r whose computer broke asked me to post
>> this question.
>> What is an acceptable liner height setting for steel shim
>> head gasket on 4cyl TR engine? Seems the one he's
>> building has a variation of approx 2 thous from right
>> side to left of block on the 3 and 4 cylinders.Right
>> side is 3 thous, left slightly more than 5. After first
>> try assembly and startup it leaked even after retorque.
>> The block seems to be the culprit as a low spot
>> seems to reside next to the liners. He's now trying
>> a copper sandwich style to see if he can make a
>> race this weekend but looking for feedback on what
>> anyone else has been able to get to work.
>>
>> Thanks,
>> Bill D
>> Triumph Rescue
>>
>>
>> === Help keep Team.Net on the air
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>
> uncle jack
>
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