O320 prop spacer question

Have an O'320 with a fixed pitch prop 2-1/4 spacer and a Sam jam shorty cowling. I am running into an issue were the cowl is to short to fit. Dose the O320 and fp prop use the spacer?

BStoddart said:

Have an O'320 with a fixed pitch prop 2-1/4 spacer and a Sam jam shorty cowling. I am running into an issue were the cowl is to short to fit. Dose the O320 and fp prop use the spacer?

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The old long spacer for fixed pitch was 4". That worked with the "long cowl".

The current standard spacer for fixed pitch is what you have 2-1/4". Constant speed props do NOT USE SPACERS. A standard Hartzell CS prop is equivalent to a fixed pitch prop with 2-1/4" spacer. **

The answer is short cowl is correct for CS prop cowl or fixed pitch with 2-1/4" inch spacer.

Van stopped offering the longer cowl awhile ago. SJ does offer the long and short cowl. The difference between the cowls is about 1-3/4 inches.

When you say short, how short? The spinner goes back from the backing plate a good bit. Not a fixed pitch spinner expert, but spinner aft edge ends behind the prop an inch or so. You are likely OK.

Most cowls have some extra to trim... Is your engine mounted? Dynafocal or Conical? Take some measurements from front of prop flange to front of cowl loosely placed. Someone will chine in. Then check your spinner installation (estimate it).

I would call Sam and ask. It may be possible someone trimmed this one too short? Sam is a good guy CALL HIM... he prefers that to emails. He will give you the dimension the cowl should be. Don't do anything to the cowl so you can return it if needed.


** (There is Hartzell CS prop that would use a longer cowl, not to confuse you. It has a longer hub than the standard Hartzell. These props are more rare, used on planes like the Twin Comanche. C2YL I recall was code))

So after a lot of research, here is how it all turns out. If you have an O-320 in a RV-7 the mount from Van's is approximately two inches longer than the O-360 mount. I read a lot of engine mount posts in VAF and saw a few notations about using the O-320 mount to correct aft CG on the O-360 airplanes. Sent a query to Vans about mount lengths and they replied thee is approximately a 2 inch difference in length. Contacting the folks at James Aircraft (it changed ownership a few months ago), they were surprised to learn of the mount length difference as well. But the new owners are making all this right (many thanks to Mike R, one of the new guys). So the lesson here is there is a difference in mounts between engines. In a similar fashion, it looks like the RV-9's use a longer mount with the O-235 and short mount on the O-320.

Good info on both parts, engine mount length and change of ownership of sam james.... Hope Sam is well. Cool guy....