Shaving stock heads questions

[LakeFever]

Putting my 200FF back together and want to know what the consensus is on how much to mill off stock heads for 91oct fuel? I want to err on the side of caution but want to get the snap I can out of it. Running premium almost certainly ethanol laced up to possibly 10% and running aces additive. Timing im thinking 23 degrees. So what do you all say for a target CC I should cut to?

What’s the stock CC on 200 fishing mota heads?
are there differences in CC between the 150xr6, 200EE, and 200FF heads in stock form? I have all of these and by eye they look the same.

How many thousands of cut equates to 1CC tighter chambers?

Any other pointers fire away

thanks

[25two.stroke]

34 cc is your target. CC em and then measure the dia of the pocket and calculate the volume of a cylinder to determine how much to mill off.

[LakeFever]

34cc it is. As for the milling depth I guess I was hoping for the easy answer. Every 6 thou off a sbc head is 1CC for instance. Car stuff I know. Still learning this Merc stuff but if I have to measure I’ll measure.

Any differences between the factory heads I asked about?

[wogi]

34 cc is your target. CC em and then measure the dia of the pocket and calculate the volume of a cylinder to determine how much to mill off.

don't want to hijack this thread but hey 25two.stroke, your pm is full I have been trying to send you one for quite a while

[gmorgan]

.010 off should be .7 cc.

[LakeFever]

That’s what I was hoping to discover. How many CC’s are the stock chambers? Are the stock fishin motors all the same CC?

[rock]

I also used .7 cc per .010 as a base line however to do it right you need to cc the head which is very easy. Buy a cheap plastic burette and know for sure.

Rock

[LakeFever]

My machine friend is old and very capable but he runs the machines and that’s it. I have to tell him to cut whatever and that’s the main reason I was looking for an easy cut depth target. I have multiple sets of heads so I think I’ll start the first set with .008” cut aiming for 34CC and see how it goes

[rock]

You may want to cc the head before you start cutting cuz there are different cc heads.

Rock

[LakeFever]

That was info I was definitely after as well so I’ll cc before sending. Thanks gents

[4Speed]

When I had the heads milled on my 150 2.0L years ago by Gene at G-Force Technologies he said that the heads were cast units and the CC's could vary as much a 2 CC per hole. He used the burette and found the largest volume hole and bored the remaining holes so that the volumes all equaled the largest then milled the head as one unit. This way all cylinder CC's were equal and as long as the cylinder and rings were good, the compression across all will be equal.

[LakeFever]

So my burette arrived today. I cc’d my stock 200 heads. I don’t think these have ever been cut they sure don’t look like it. Anyways, 34cc is what they are so I’m running them as is