I just picked up a Dynaflight 1/5 scale spitfire that was flown with a Saito 150. I am installing a YS 1.20 fz. Using the existing mounting holes on the wood rail motor mounts, my prop hub ends up about 3/16" behind the built in cowling of the plane. Look at the pictures below.

Is there a thicker prop hub available to fix a situation like this? Can you offer any other suggestions?

I don't want to attempt redrilling new holes in the motor mounts because I cannot get new blind nuts on the back side of the mounts, there is not enough "meat" to support new holes without moving the engine forward a good 1/4" or more. This will then leave a huge space behind the spinner backplate.

I am open to any ideas.....
Tyler

Tyler,
Any pics of the motor mount itself?
If you move the whole engine forward a 1/4" and drill the new holes, and its 3/16" behind the opening now, that would put the backplate at 1/16th" in front of the opening which is where I would think you would want to be. The other option I guess would be to cut off the rails flush with the firewall and use a traditional motor mount bolted right to the firewall.

Warren

To repeat +1/4-3/16 = +1/16.

pic 1

mount2

mount3

mount4

Hi another option is to remove the blind nuts if any and fill the holes with epoxy or JB weld sand flush and re drill!

Regards
Mark

I realize that what 4*60 says is true: "To repeat +1/4-3/16 = +1/16." I meant to say this would be the ideal solution if redrilling holes could easily be done.

Perhaps filling the existing holes, knocking out the blind nuts, and trying to start over again a little forward on the mounts is what I will have to do. However, I anticipate many frustrating hours of work.

The current holes are tapped all the way through the plywood doubler and the spruce mount, which is something I could not duplicate on my new holes because I don't have the space to work or the tapping tools available.

In order to remove the blinds nuts already there, I think I will have to drill the existing holes out to eliminate the tapped threads, install the mounting bolts again, then tap the blind nuts out using the screws and a hammer. I tried tapping them out as they are, and I am afraid the plane will suffer damage before the nuts budge. Those threads in the wood add a lot of strength and holding power, which is one reason I don't want to redo the mount.

Tyler

Another concern I had was drilling new holes close to the existing ones after filling them with JB weld or epoxy. If my bit catches the JB weld, will it prevent nice straight drilling through the wood, or does the weld and epoxy cut easier than the wood. I have often found it difficult to keep the drill straight when two different materials are being drilled at the same time.

I ask this because I will have to enlarge the original holes in order to remove the blind nuts. This won't leave much, if any, space between the two sets of holes. I am afraid they may overlap, thus causing redrilling problems due to different materials.

Tyler