Re: Dumbo The Flying Elephant
 

Larry -
If you are going to make a flat cut on the head to reduce combustion chamber size, here is an easy way to know exactly how much to cut. Put the head on a stand with the combustion chamber facing up. Shim or adjust the head so the head surface is level in all directions using a level. Then, pour the combustion chamber with the amount specified for minimum volume. Use a dial indicator on a bridge to measure the distance to the surface of the fluid from the head surface. Do that for all cylinders and adjust the numbers to determine how much to cut.
This method will work on any head regardless of combustion chamber shape or size.

Re: Dumbo The Flying Elephant
 

Thanks Phil and Dwight, I will fill and check to see if 5cc will be .030''

Re: Dumbo The Flying Elephant
 

Take a piece of graph paper and trace a outline of the combustion chamber shape on the paper. Count the number of squares on the paper that are within the traced area. Do the math to calculate the area of the squares. From there you can calculate the volume. This method will get you close. Double check the volume with your first pass on the mill.

Re: Dumbo The Flying Elephant
 

Hopefully it wasn't the good stuff and by losing 1/2qt do you mean spilling it or drinking it?

Re: Dumbo The Flying Elephant
 

I spilled it, but I did buy a small funnel that fits the burette.

Yesterday was recording day in the "Dumbo" engine book. The engine I got came in several boxes, for me its the only way to get one. Most boxes have the brand name and part numbers. This make replacement parts hunting easier. Other parts are in plane white or brown wrappers without part numbers. Such was case with the spring seats for the head. Exhaust and intake have different seats, valves are not the same length. So I make a drawing of each in case I can't find a vendor. If push comes to shove I will be able to find some in some bar stock.

Since I had the heads out I would see how well the seats fit. They almost fit but would not set flat against the head. The problem was the OD of the chamfer was not large enough to have clearance over the radius on the head. Solution cut chamfer 1/64 bigger than the chamfer on the guide boss. I was surprised as to how soft and easy the spring seats machined.

I wonder how much unwanted aluminum the seats would have shaved of heads and put in the oil?

Re: Dumbo The Flying Elephant
 

Done it this way for decades.

Use a dial indicator and bridge or a depth micrometer and some ground tool stock for parallels. Once the chamber is filled with the specific amount of fluid, lower the tip a thousandth at a time. Watch the tip of the indicator or micrometer, when the tip touches the fluid the surface tension will attach the tip. You can then calculate the amount to remove.
If your surfacing machine is really level, you can do it right there....you're not going to bump the head out of level after it's bolted to the machine.

Re: Dumbo The Flying Elephant
 

Since all this gen 3 stuff is new to me I am going to check piston to valve clearance, before I do any cutting. Thanks to you guys I have some direction on doing it correctly.

Re: Dumbo The Flying Elephant
 

Just finished cc's on the heads. It should make more power now that I'm done. Growing up I always heard, ''If you want to go fast get some heads that have been cc'd from Racing Head Service.'' Well I sure hope my cc'ing is as good RHS. Time will tell.

Re: Dumbo The Flying Elephant
 

I bet your work is "A-1" and maybe we will say " if you want to go fast, get some heads cc'd from LHS."

Re: Dumbo The Flying Elephant
 

Today we start checking installed height, seat pressure, open pressure, and adjusting to make equal. It's going to take a while.