Solas amita 4 blade makes engine flare / rev when trimmed up?

[Fordiesel69]

On a friends 19' sea ray SRV 190 we switched out the old skool michigan wheel 17p 3 blade for a Solas Amita 15p 4 blade and now when you trim up the drive, the engine will flare up. We even noticed this with the trim all the way down. What would be the cause of this?

It kinda sounds & feels like cavitation like when you have it trimmed up too far, but rather it is not up too far.

If a hub slips, it is usually done for so we would have needed a tow, right? Merc drives are not designed in such a way as to slip, so I guees we can rule out an internal drive issue. And lastly the drive coupler, if it were failing, wouldn't this ruin the splines on the input shaft & produce more of a grinding sound / feel? It looked absoultly perfect and in alignment when we commsioned the boat.

 

[steelespike]

Re: Solas amita 4 blade makes engine flare / rev when trimmed up?

Usually the Solas Amita produces very predictable results.Nothing to do with the slipping but:
Both prop sizes seem small what is the the whole outfit.year,hp/displacement,dry weight.
Its not unheard of for a new prop hub to fail. It is possible to be spun and grab again but likely would spin under enough power.Wouldn't be unusual to be able to run gently and not slip.
Once spun it would very likely spin again when power was applied in a similar fashion.
Go back to the Michigan and see what happens.
As I understand it there is a drive coupler that can be spun.

 

[Fordiesel69]

Re: Solas amita 4 blade makes engine flare / rev when trimmed up?

19' SeaRay 190. 120HP 4 cyl, pre alpha. Indeed it had a 17p which performed ok but was beat up. The new 4 blade was dropped 2 pitch sizes as a result of being a larger diameter as well.

How can a drive couplerw slip? It is metal, and will eat the splines up on the input shaft which has NOT occured. We will stamp the hub and prop.

 

[craze1cars]

Re: Solas amita 4 blade makes engine flare / rev when trimmed up?

Your engine coupler is not all metal, it has metal spline insert and held in place by a bed of rubber. The rubber can and does fail, no different from a spun prop hub. And failure will cause your engine to over-rev under load. But most commonly when they fail you will simply be limited to about 5-10 mph max, and if you give it any throttle beyond that will just cause the engine to race. Usually you are forced to idle home when they fail.

I'm not saying for sure that is what is happening to you here, but it is one more thing to check. Photos of engine couplers:
http://www.sterndrive.info/sterndriveparts/engine_coupler.html

Are you absolutely certain you are not simply under-propped and therefore over-revving? 15 pitch is awful small, but we don't know your outdrive ratio, speed, RPM, or anything else either...

 

[Tail_Gunner]

Re: Solas amita 4 blade makes engine flare / rev when trimmed up?

19' SeaRay 190. 120HP 4 cyl, pre alpha. Indeed it had a 17p which performed ok but was beat up. The new 4 blade was dropped 2 pitch sizes as a result of being a larger diameter as well.

How can a drive couplerw slip? It is metal, and will eat the splines up on the input shaft which has NOT occured. We will stamp the hub and prop.

The new prop is larger in diameter...The prop must be flush to the outdrive not larger nor smaller. Take a pic and post it if you can

In most cases the below pic is a no no for i/o's That prop is to small and it can be to big..