Just have had time to finish taking apart my '73- 225 and would like
to aim for right at 10:1 compression. Im having the block bored .040
and would like to know where to start with the amount of shaving to
the head and block to get about in the 10:1 compression range.
Thanks everyone....

I personally think shaving the block and head are only 2 of the variables...........

You need to know the CC's of the Head (after valves and chamber cleanup)...

Pistons......... type, valve relief volume, distance below zero deck, do you want to correct distance below zero deck with pistons or shaving.........

head gasket thickness, hole diameter of head gasket.

Trying to get squish in the combustion chamber???????

See where you are, then see what can be changed to get you to 10:1...........

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I agree with Ed. Decide on piston/rod type (stock?) and measure CC's of 1 to 3 of your head chambers and we can go from there.

Lou

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Home of Slant6-powered fun machines since 1988

There is a lot to this....as I recently discovered.

If you use larger valves the combustion chambers should be radiused,,,this increases chamber volume. If you bore notch for larger valves it increases bore volume.
Rather than bore notch I chose to just surface the head and mill the block to achieve my target CR. This left plenty of radius room above the bore to prevent valve shrouding.

If I used stock valves with no chamber mods and wanted more "squish" or "quench" I would just surface the block and mill the head.

The more you mill the head the more accurate your CCing needs to be.

There is also the possibility of angle milling to increase quench.

If you use larger valves and a big cam you need more room between the block deck and valve face to prevent interference or shrouding.

If this is a street motor, is there a reason for 10:1?

What cam will you run?

There is a lot to look at ....and it pays off to look.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Well, It looks like I do have alot to think about there...the cam specs start
in at around .480/.480, 230*of in/ex duration at .050 valve lift. 110* LSA.
Yes this is a street engine, but If I think about it there probably wouldn't
be alot of power difference between 9:5:1 to an even 10:1 compression.
This is not a daily driver project for sure but I do gotta retain some streetability with it. The engine will use the stock 225 rod length and
.040 over sealed power s6 pistons. The 10:1 compression idea was a suggestion from the cam grinder, so I thought that would be a good
starting point. Thanks and if you guys have anymore suggestions
let's hear them....

P-S- The engine will be getting larger valves as well......

Why only go .040"? The bigger the bore, the better your head will work. Bigger bore unshrouds the valves.

_________________
Official Cookie and Mater Tormentor.

You save the .060 for the next rebuild when you've screwed up this one...............

_________________
Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

.040 over is just what happened to be available and I am on a budget.
I rounded this set of new pistons up for $50...

And then if it does screw up, I'll take it .060 over..

OK, can't beat that.

_________________
Official Cookie and Mater Tormentor.

ya dang that is cheap i just looked on summit and it is 9.99 a piston good deal

^^oops that was my bad first time registered on here ^^