Perkins 4-108, Max Revs and KiwiProp

[MikeNZ]

Very interesting thought, John.

Wouldn't surprise me one bit based on all the other messes I inherited. However, I am getting there and the learning process is a reward in itself!

Thanks again for your help.

Mike

[MikeNZ]

Here is the latest.

Got the boat onto the slipway last week. Prop supplier re-pitched the Kiwi Prop down a full turn on the blade set crews which should have given around 600-800 rpm increase according to Kiwi Props website. Cleaned the bottom too so I could get an accurate comparison.

Took her out for a spin and we saw max revs go from 2,500 to 3,050 (550 rpm gain).
Can't get more than 3,000rpm though and when I try (there is some throttle opening left) I get black smoke.

So I'm on the right track I guess....

Issue I have now that I didn't have before the IP was 'recalibated' is that I seem to get a lot of fuel in the exhaust throughout the rev range, even at medium load (say 2,000 rpm). The prop supplier has now told me that the compnay that did the IP recalibration said they did two things to it - reset the max revs from 4,000 to 4,400; and increased the fuel delivered.

Does this sound normal and why should the fuel quantity and max revs have been wrong in the first place?

Will excess fuel damage my new engine?

Any comments welcome.

[MidLandOne]

Originally Posted by MikeNZ

...The prop supplier has now told me that the compnay that did the IP recalibration said they did two things to it - reset the max revs from 4,000 to 4,400; and increased the fuel delivered.

Does this sound normal and why should the fuel quantity and max revs have been wrong in the first place?

Will excess fuel damage my new engine?

I don't know the answer as to what is causing the excess fuel in the exhaust Mike beyond guessing from an uninformed position. However, some other comment might bump the post up in the list again and bring it to others attention (I would also consider contacting Alan Wheeler).

Regarding the "sound normal" and "why wrong in the first place" points tho' -

If there is more than a light film visible on the water behind the boat when stationary, especially after the engine gets up to temperature, then would seem to me unusual and a possible problem. If you can see it on the water when motoring then I would be sure you have a problem.

Regarding the fuel quantity and max revs being wrong in the first place, I would suspect that someone has had a play in the past. The points of adjustment often have wired seals on them (have no idea if that normal on the 4-108) to discourage tampering - were there any?

Hopefully someone with good engine knowledge will comment.

[MikeNZ]

Thanks again John

I would like to shout you a beer for all your help! You around over Xmas, or heading down South? Send me a private email if you like.

Mike

[MidLandOne]

Hi Mike. Would sure like to meet up with you. I'll send you details of our expected movements, contact details, etc.

John