IO-36O w/Hartzell C/S prop spacer?

I just switched from a MT 3-blade to a new Hartzell constant speed to shift the cg forward a bit and the Hartzell sits a little closer to the engine...enough so that the nose of the cowling contacts the spinner backplate. Any ideas other than reworking the nose of the cowling? I only need to gain about 1/4" of clearance. Is it possible to put a 1/4" spacer between the crankshaft flange and the prop hub on a constant speed prop? Is there any downside to shimming the engine mount away from the firewall 1/4" to move the entire engine forward? I really hate to redo the cowling...
Bruce
RV-7A (purchased)

Two options:

- First choice - adjust the spacers in the backplate to get the needed cowl to back plate clearance. For each 1/16” washer added to move the spinner forward you will need to add 1/16” washers to the back of the front spinner plate to move it the same distance forward. Some epoxy works well here. Be mindful of the minimum of keeping the spacer that came with the prob between the prop hub and the backplate. This is covered in the Hartzell instructions.

- Second choice if this does not buy you enough space. Add large diameter washers between the engine and the engine mounts to get the clearance you need. Don’t forget to get longer engine mount bolts if needed.

With an engine hoist you can do this without taking the engine off the plane.

Carl

Thanks for the input Carl!

I am also fitting a new spinner to go along with the new prop (going from 3-blade to a 2-blade) and I believe I have the minimum spacer stack on the forward side of the backplate, in the process of fabricating a tool to rotate the prop blades through their range of travel to verify backplate to prop clearance. Currently I have the supplied spacer and one washer between hub and backplate, I may be able to go with a slightly shorter spacer or spacer with no washer but that will still leave me considerably short.

I never considered the engine mount washer trick, I will look into that. Thanks for your help!

Bruce