Thin head gaskets.. More comp etc, etc

[loosecannon]

Hi Guy's,

I have a 94 1uz in a boat, I will soon be changing the valve springs, , while the heads were off I thought I would try and get more compression via Thin MLS head gaskets, So I just want to see who has tried it, and how much increase can I expect for a particular thickness in gasket

The class this boat is used in is N/A only, so looking for more power ( while the heads are off anyway)

Thanks in Advance

 

[XR8tt]

Another option is to machine heads alittle ???
It will play with cam timing, but so will thinner head gaskets..
Just check piston to valve clearance..
model clay on valve notch and turn engine over two turns..
Check clay thickness..
Mild cams really wakes these engines up too...

 

[poweredby1uz]

How do you work out compression ratio? ie if the shock gasket is 0.059 with a 10:1 ratio what would 0.049(1.25mm) head gasket make it?

 

[loosecannon]

Thanks for the replies,


You would think it would be ok to skim the heads a bit , as well as thin gaskets, without valves hitting pistons, as most engines allow some room for the head to be machined, be it from a warped head from an overheat etc, or engine rebuild

Just have to figure out what that limit is, and what the increase in comp will be

 

[XR8tt]

That's why you use clay or even kids play doh..
Only need to do one cylinder and allow .080 clearance...
Yes I think you'll find there's way over .100+ std..
Never checked myself with std cams..
I assume being a boat engine the rpm is quite high ???
This is why cams would make it really boogy...
Just setting up valve clearance takes some time !!!
To measure comp you need to know what you have now..
CC head, CC piston valve notch's etc.. Head gasket thickness, piston to deck height..
Then fill this out..
http://www.summitracing.com/expertadvice/storydetail/calcsandtools/Compression-Calculator/

 

[loosecannon]

That's why you use clay or even kids play doh..
Only need to do one cylinder and allow .080 clearance...
Yes I think you'll find there's way over .100+ std..
Never checked myself with std cams..
I assume being a boat engine the rpm is quite high ???
This is why cams would make it really boogy...
Just setting up valve clearance takes some time !!!
To measure comp you need to know what you have now..
CC head, CC piston valve notch's etc.. Head gasket thickness, piston to deck height..
Then fill this out..
http://www.summitracing.com/expertadvice/storydetail/calcsandtools/Compression-Calculator/

Thanks for that, I'll get the clay out and have a go,

I am going to do cam's as well,, just waiting for a second hand set of mild cams to come up for sale, so keeping my eye's out

 

[ash]

Don't only measure 1 cyl.... That's where mistakes are made
What's to say the cams were ground wrong?

And... Check with cam grinder...where the advance is.
More or less advance changes where the piston " chases or gets chased" in regards to valve- piston relationship .....