I`ve got a 1/3 scale tri pacer with a 45cc poulan conversion, what are the pros and cons of putting the engine on rubber vibration dampeners?
thanks for any info, RCM 243

The pro's are if you get it right, the reduction of much vibration.
The con's are if you get it wrong much much much more and worse vibration.
I had great success using Hayes beam style isolation mounts when used on a GP UDO 46 and a Saito FA82. It took all the drumming of the covering out. Turned it into a pleasure to fly.
Each airplane/engine combo will need a slightly diferent type of isolater. The experimenting and finding success is the fun part for me. If you dont want to spend a bunch of time experimenting try the hayes mount.
If all else fails switch the conversion parts over to a Echo 45cc engine. There won't be any more vibration.

If you are doing a radial mount 3 or 4 points, put all points on a different radius and at odd angles from the virt/horz center point, then each point will be at a different vib/harmonics, works for me on a G-38

bob t

MY mistake, this engine is a stihl and it was converted by Brillelli, the rubber I`m considering is 3 quartes of an inch round and 3 quaters of an inch thick with a stud on one end and a female thread on the other, I was going to put them between the beam mount and the firewall. the mount is made from aluminum angle.
RCM243

Sure will not hurt to give it a try. The aluminum angle should be at least 3/8" thich and an inch wide with 1/2" by 3/4" wide being better.
If you have access to a truck salvage yard you can get aluminum frame rail pieces that have very good strong aluminum.
Aluminum doesn't flex well. It fatigues easily. So make sure they are ridgid and the rubber does the flexing.