I need to make some cutouts in a glassfiber cowling for the valve covers. (hangar 9 thunderbolt 60size(saito 100)
If I use the cardboard method I can trace the cutouts on the cowling, but I must remove the engine to fit the cowling.
My problem is that this cowling has a dummy radial engine and just a small hole for the drive washer to enter out trough.
If I remove the engine and place the cowling at the right distance from the firewall, I am still not shure if the drive washer is centered in the dummy radial engine opening.
Tips pleace anyone?

I am not positive if I understand you exactly but I THINK I do ...here is what I think you need to do...

1 get a long board
2 strap your fuse down to it secure..use some pads make sure it can't move...
3 take a small board and screw it down in front of the plane with two screws.
4 put a nail or screw in that board so that it just touches the center of your crankshaft.
5 now you can remove the small board, and replace it later in the same spot using the same holes.
6 remove motor from plane without fuse shifting on main board.
7 install cowl so that it centers on the nail, once small board is repositioned...
8 be careful not to position cowl too far out...

Hope this helps, I think this is what you were wanting to know?

FOODSTICK you understood my problem and answered it so good that i see it in pictures.
thank´s a lot!!

No problem, glad I can help out..

I've read in other threads here, and am waiting to try myself, that some use those lazer levelers sold at home centers and or the cheap laser pointers may also do.

Strap your plane down as noted above.
Install your motor and set the laser to point at the center of your motor.
remove the motor and install the cowel and the laser will point at the location to start your trimming.

this also works with trimming for the valve covers and such.

Hope this helps also

Bill

The Laser idea was smart!
I`ll try that another time.
The cowling is finished and came out perfect with 4 holes in it and the prop driveflange perfectly centered.