http://www.bbcboards.net...-here
Maybe somebody here can answer a few of these questions.
http://www.bbcboards.net...-here
Maybe somebody here can answer a few of these questions.
Do I want my rpm's up?
Yes. IF the tach is accurate. You want to be up around 55/5600 rpm.
Do I need a different prop?
I've heard lots of people say those shooters were junk. If you're truly getting the speed you mentioned, then they would all be wrong. So something doesn't quite add up. I would think a 24 raker would work well and have your rpms up close to where you want them.
Why does it not lift up much at takeoff?
Prop's biting good, with plenty of stern lift.... that's not a bad thing. Out of the hole in 2 seconds is good.
Why does it seem to ride perfect when trimmed all the way down and see no change, except steering getting looser, when bumping the trim up?
Makes me wonder if there's an issue with the trim - can you (or your buddy) visually see the motor trimming up? It should be like night and day from fully trimmed in and fully trimmed out.
I really can't imagine it running any better, it was easy to drive and handled the water well.
There's the ultimate test! But to be honest, something just doesn't add up. I tend to believe the rpms, given you've got a 27" prop on it. Two things stand out to me:
1. Yes, the speed is hard to believe - is that a Zercom GPS, or some other unit that is hooked up to read a mechanical speedo pickup? My guess is it's a mech speedo, and is reading much higher than the actual speed (as they all do).
2. Are you 100% sure your trim is working correctly. From what you describe, it sounds like it's not trimming out as far as it should, but it's difficult to say.
Thanks for the reply. To answer a few questions, yes the trim is working correctly, and no the zercom is not gps. Like I said, I'm sure the speed is off, but I would definately say we were in the 60's. My dad's a grease monkey gearhead and even he was thoroughly impressed. Previous owner said it would do 63. The trim does work, I watched it go up when pops was driving.
Maybe I was just expecting something different. I remember a few boat rides in the past when the guy gunned it, it would stand up and you could barely see over the bow til he trimmed up and set it down. When I gunned it, it was just level and haulin azz in no time. In really rough water when you want to get the bow up, I don't think it would do it. Since I'm only turning 4900 rpm at wot, what would putting a lower pitch prop do? Can it be damaging to the motor to have it propped like it currently is? I can't imagine it performing any better, I guess I just don't know what I'm missing.
When trying to set up a boat and determine how it is running/handling - you will need the basic information:
1. GPS speed is a must. Going 50 mph seems fast, until you truly see 60 plus. You at least need to get a handheld gps to use for this purpose. Without true speed, nobody can really give you good input.
2. True rpm's. If your tach is working correctly, then you can estimate your speed. Google prop slip calculator or something like that. There are several sites that you can input your rpm's, gps speed, prop pitch, and then it will calculate prop slippage.
3. Current set-up. This will include your prop to pad measurements. There are instructions on the boards on how to measure this.
4. Max rpm range for your specific engine and what the gear ratio is for your engine.
With this information, you can get great help on the boards. You can also do searches and have enough information to make most decisions about new prop, engine height, etc.
Good luck
jumping out of the hole fast and low= low pitch prop, low mount on transom or jackplate(which will contribute to the low rpms)
assuming trim is working...try a higher setting on the motor height(lose some holeshot but gain rpms) and a larger pitch prop(just because you said it came out of the hole so fast).
if prop is out of adjustment (like bent a little) it can keep the nose from rising under trim. you don't really want the nose way up on take off.
remember baby steps are better so don't go way far on trying stuff. borrow if you can without buying. give some lunch money for trying props and stuff. $20 to try one is a lot better than $300 to buy and then trade losing money.
your should be fully trimmed down when coming out of the hole. this will keep the nose from really standing up as you described. if you're in the 60's with that and only getting 4900 RPM I'm guessing your tach has to be off. If it is in fact really 4900 rpms then a lower pitch prob will get your rpms up.
Modified by Astro-T at 7:36 PM 4/26/2010
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