Just curious which prop would be a good starting point for this combo.
I just bought this boat out of Arizona and it has a Raker prop on it. I cant find a pitch number written on the prop. While at Arizona elevation the boat was running about 55 mph empty other than 3 decent sized guys in it. It was also only turning 5000 rpm.
I am bringing it to the Denver area and 6000' ish elevation. I will get actual p2p, mph, and rpm numbers next week but I was curious where I should start with props.
1000 ft of elevation equals a drop of about 100 rpms. 22 Raker or 23 tempest would be my sea level choices for that rig, so compensating for altitude, look for a 20" raker that can be worked, they all need work.
Pat Goff
Two degrees from center
of nowhere.
Smithwick TX.
Thank you sir. I'll have some actual numbers to work with next week and I have an extra 21 Tempest (I think its a Tempest) sitting in my shop so I might start there and see where I'm at.
To be continued.....
By the way, I have read your history of Champion during my research while looking for boats. Very informative and interesting. Thanks for taking the time and doing that.
Make sure that prop has the johnrude hub kit.
Altitude really kills a carb motor, might take a few stabs to find the right setup.
Pat Goff
Two degrees from center
of nowhere.
Smithwick TX.
Good reminder, it did come off a Merc so I'll get the correct hub.Originally Posted by pmgoffjr
The little things that make you old before your time.
Simply from experience....
Pat Goff
Two degrees from center
of nowhere.
Smithwick TX.
OK, some real numbers.
The original prop that was being run in Arizona was a Raker 22. To recap, the boat ran 55 (speedo number) at close to or at 5000 rpm.
I changed props to a Turbo (Precision Props) 19 pitch and today at my elevation with 1/2 tank of fuel, full livewells and my normal load, I ran 50 mph GPS, at 5400rpm I measured p2p and it was at 5 3/8".
I was happy with the rpm's and to be honest I'm not real sure I can expect much more from the 150 at the 5500' elevation that I am running at.
Does anyone think I should try raising the engine and what results should I expect from that? I am in the second from top hole right now.
I you are going to run at 4000 and up elevation, have the timing reset for about 4 degrees more advance. Verify the correct p to p with Pat but I am confident that it should be less than four inches. The additional timing will help the hole shot a lot. Don't forget to put it back to spec when under 4000 ft though, I would consider a tempest 19p prop as well. Also check the plugs for after a few hard runs for any signs of running to hot and/or rich/lean conditions
Thank You Leon Pugh
That turbo is far from optimum. You got a decent pitch number from your rpms, but there's more to be had.
Now, I don't try to fix stuff that ain't broken, and if you like it, I love it. But...a high rake three blade (raker/tempest) will give you better results.
Flipping high/low altitude is a pain, but it is what it is.
Pat Goff
Two degrees from center
of nowhere.
Smithwick TX.
OK, I'll start looking for a Tempest prop. I think I can trade the Turbo in for a new Tempest.
Pat, whats your thoughts on my p2p?
Timing and also jetting. You guys are right, that is going to be a PITA. I run here most of the year at altitude but make at least one yearly trip to Table Rock. I was really hoping to not have to mess with that but.......... Let me ask this. Is leaving the timing and jetting where they are doing any damage or just a loss of performance?
I worry more about being too lean when going to lower elevations and really doing damage. If I can optimize my set up with p2p and a good prop but I leave a little performance on the table without doing damage with the current set up, I think I would be satisfied.
Thanks for the replies, much appreciated.
You will mainly just lose power at high elevation and will tend to foul plugs. Timing is the big one, when advanced for high elevation it will be to much for low elevation
Thank You Leon Pugh
Everyone wants to hit the easy button. Sometimes there isn't one.
Motor height is one of my sources of aggravation. Way too many people tell someone set it *here* when *here* might or might not be right.
The ONLY way to set height with a jack plate installed is take it too far and bring it back. Takes some time and effort but you have to know what too high and what too low is.
You didn't say if you had a plate? If not it's simple, motor should be in second hole up, and that's it.
The boat will tell you what it wants. Always test with your normal fishing load, if you setup light it'll never run right loaded.
Too low: numb steering, flat/no tail, rpms lower than should be.
Too high: very stiff steering at WFO, roostertail higher than motor cowling, boat runs flat no lift, water pressure low.
What we don't understand, no two anythings are exactly identical. For sure no two props, motor output, weight, all are variables that can change.
Pat Goff
Two degrees from center
of nowhere.
Smithwick TX.
No jack plate and engine is already in the second hole from the top so that is pretty well settled.
The information on symptoms for too high and too low is great information. Being a rookie at this I was wondering what exactly I was looking for.
Thanks for taking the time to look at this and respond. I think I will change out the prop and see where I'm at and I can be happy with that.
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