Logo
FULL SITE MENU

Solas Prop on older 40hp

T

TGBTG7701

Member
I have a Solas Stainless Steel prop that came off a 40hp Suzuki outboard that I had. The spline count and diameter is the same and it slides on my 40hp early 90s Mercury 4 cylinder outboard perfectly. The only difference I see, it does not have the two tabs to hold the locking washer in place like the OEM aluminum Mercury prop I have one there now. I would like to use the Solas prop, is a little large in diameter and one step up on the pitch. Could I use this prop, or should I try to find a Mercury prop?
 
Your engine will work harder, WOT will decrease,and your speed might decrease also, Not a good idea,highly not recommended! wait for other replies
 
I just prof read the post, the Solas prop is just a little bigger than the OEM, and 14 instead of a 13 pitch. I have decent top end, but I have very little bottom end, have to lay into the throttle to get the boat going. I am trying to figure out why my bottom end is so bad, it had a lot of bottom end with the Suzuki motor using this same prop I am asking about here. I have a lot of top end, had a friend of mine try and keep up with me, his boat is aluminum like mine, similar hull shape, but weights a lot less, his new 4-Stroke 40hp Honda could not keep up. There is an area I fish, I go through about 3/4 mile no wake area, most of the guys are just putting a long, and I am at 1/4-1/2 throttle, but when we get out of it, I open it up, and I am gone, few MPH faster than the rest at full throttle. My Mercury seems to run like a top, run good cold and great when it is warm, just can't figure out why it some slow on take off.
 
Hard to compare apples to Mandarin oranges! The Suzuki may have a different gear ratio and that'll drastically affect prop performance across 2 different motors. Plus who knows, the Zuk might be a bit stronger than the Merc 40hp, no 2 mfr's are identical as far as hp goes, there is a bit of leeway in the NMMA ratings.

With your motor already having good top end and fair/poor hole shot, switching to a larger-diameter prop with more pitch will definitely make it worse.

The best way to determine the correct prop for the motor/boat combination is with tachometer readings. The WOT (Wide Open Throttle) with the boat lightly-loaded (i.e. driver-only) should fall to the higher-portion of the mfr's rpm range. That way with a load, you'll still be within the lower part of the rpm range and won't be lugging the motor.

If all you lack is a bit of hole shot and don't want to lose your top end, you can go to a stainless prop in the same-sized pitch. The thinner blades will be less load for your motor and it'll spin up faster.

You can also drill ventilation holes in your prop body for an improvement in hole shot. The exhaust gasses pass over the prop blades and cause a "controlled ventilation" which allows the motor to spin up faster, getting into its power band quicker. I've attached some info on that.

HTH.......ed
 

Attachments

  • Prop Ventilation Holes Info.jpeg
    Prop Ventilation Holes Info.jpeg
    51.7 KB · Views: 24
Poor hole shot could be a carb adjustment have you tried adjusting the slow needles out 1/4 turn and see if it pops out of the hole quicker. It is allways best to adjust the slow needles a little rich to protect the motor running at slow speeds also. It will help with cold starts also.
 
Last edited:
On a side note a four cylinder 40hp merc will out perform most any other motor of the same hp just get one of those timing light tachs and take it out and see what your WOT rpm is. That will determine if you have the proper pitch.
 
Back
Top