SET BACK CHANGE TESTING RESULTS?? KINDA

[FlatOutAlly]

I used to run 14 1/2 with a Promax. When GPI got the boat the motor got moved in. It's not so touchy this way, and when you're running fast and need to slow down quickly for a boat wake or whatever it no longer demands that you dance with it.

The more hp, the less setback needed. No doubt about it. Not really sure how much hp I've got right now, but probably more than a Promax. :shock:

 

[froggy]

Chad,

The probable reason Flying Butcher got the extra 500 RPM was that he got 3-5 more MPH. Also, an ET prop doesn't cotton to carrying a big load like Bill has and will slip. Once Bill gets all the variables sorted, he can start playing with props and he'll really be moving.

I've gone from 14.5" to 9" to 5.5" to 8" of offset. The reason I went further out, back to 8" is that I'm trying to run with slight negative trim so I can get the last few MPH my boat is capable of. Incidentally, I am running with close to the same load as Flying Butcher except he carries an extra bass seat and I carry and extra butt seat and he carries a spare prop and I don't, but I probably make up for it with all the lead jigs and such I carry. I am running a bit faster than butch also, so he has a bunch of potential left.

froggy

 

[chad202]

Oh, I see. Randy, I'm not being a smartass. I just picking your brain. Everytime someone replys, it makes you go further into detail :wink:

 

[GotMyAlly]

Catfish....I am planning to move my motor in this weekend. Gotta order a lifting ring first, but as long as it gets here by this weekend I'm gonna move mine in to the closest setting. I've got the allison adjustable jackplate and if I remember correctly it adjusts from 11" to 12.5" to 14". I'm probably going to set it at the 11" setting to see what kind of difference it makes. If the weather holds out, I'll run it this weekend, too. Been way too much wind here the last couple of weekends though.

 

[GPI Racing]

Chad,

I was just trying to get you to see what I was talking about. Sometimes typing it out and having the same idea in my head as the reader's is the hardest thing to do. I'm not the best at detailed discriptions when I have to type them out. Also no question or opinion on this forum is EVER a burden. We all are working toward a common goal and share the same passion. I don't mind answering and sharing info and experiences, enjoy it actually as I meet new friends.

Randy

 

[catfish123]

Neal.........I sent you an email.

Bob

 

[ally2dextreme]

500 rpm

could it be with your other setup you didnt raise the motor enuff?

 

[GPI Racing]

Ally2,

That statement is somewhat true but keep in mind that at low speed with the boat running flat the thing would have the gearcase so high it would look like Miss Budweiser. That is why I like being closer to begin with. Because of the radical change in gearcase effective height from low speed to high speed, I've never been happy with the long set back and the low speed compromises it creates. If the ultimate top speed is the same or within a mile an hour, I felt why go thru all the fuss. I agree that you can go just as fast with a long set back if you get the motor up. But the trade off in low speed performance and the overall handling is not near as good. That's always been my point on this subject.

Randy

 

[FLYING BUTCHER]

setback

Darn Randy stole all the stuff I was going to put here regarding the pitch ans slip of prop. None of that really makes any difference it is just handling and mph. For those of you who asked I am now at 10" and this last run was the firs one and I didn't touch the jack plate. Guess you all understand I was a little shell shocked. I will try going down a little at a time but it may be a few runs, or water a lot warmer, before I trying going any higher up. I think I know that handling thing Randy is talking about, it was like when I was running (first time ever) with a guy directley behind me WOT. The boat never felt so secure. Like I mentioned before, I wasn't real comfortable running yesterday and she did feel pretty light. Still can't get over how fast the bow came up when I overtrimmed her at 96. Never came up that fast before. Oh by the way, I didn't mention my fat butt weight, stripped (there is a sight for ya) 235#!! Lots of more drive time to do. Thanks Randy for all your expertise. Later

 

[Stace]

Thanks for sharin' all your testing FB!!! Randy I'm currently at 11.5" on an xb03 225pm combo and with the jack plates I have the next step in would just be a 6" CMC. Do you think 6" would be a little bit short? I'm happy with low 80's especially if it take less driver input. Great Thread!! as are the majority on this board. Stace

 

[GPI Racing]

Stace,

Yes, 6" would probably be too short and a BIG change. The spacers I sent Bill to do this are from Allison and not too expensive. They were originally used betwwen the boat and the 6" CMC on the Gran Sport. They are 4" and adjustable vertically. You usually only want to go a couple inches at a time when making changes so you can keep a handle on the differences.

Randy

 

[Stace]

Thanks Randy! Wish the lake would thaw. All this talk is getting me real itchy to get back behind the wheel. Stace

 

[chad202]

I really don't know how you guys can stand it during the winter.

 

[willyp]

Me either, It was 80 degrees here yesterday.

 

[JR]

APPRECIATION

Randy,
I really do appreciate you sharing your experience with us. Most of the people with your experience will only provide it secretly with a hefty price tag attached.
I really think you need to move to Florida so I could have you do my engine / setup work [My engine Guy, Curtis is retiring soon]. It's in the 70's today here.
JR

 

[KY_XB2003]

I havent read all the posts, but how much set back, typically, should I have on a 203 with a 225 promax?

 

[catfish123]

The jury is still out on that.

 

[badbait]

KYs question (how much setback for a 2003)

Now that is a good question that really does have a lot of right answers. I'm running 3 inches with a 510 pound motor. My friend Froggy say's to equal the same lever effect with a 400 pound motor you would have to put it at 8". Since he's an engineer and I'm not I'll take his word for it. How does mine run at 3". Like a scalded cat. Personally I think the setback can be as close as you want it if you have enough clearance and know how to work the lip. The problem with the lip is that one size does not fit all. When you get everything right you will have very little torque at mid-range and non on the top-end. Yes I believe YA when he said he could take his hands off the wheel at 100. Plus you should be able to pick the nose up at any speed starting at 35 mph. When you get there in my opinion you have it right. I think I would have to go a long way to find a 2003 that handles better than mine, I don't care what motor there running. Plus I think I would surprise a lot of 280s that are running 14.5" of setback in a drag race or top end. All of that with a heavy green motor.

 

[GotMyAlly]

Badbait, are you running a stock L/U or a worked L/U?

 

[badbait]

Yes, my gearcase was worked by me using Ideas from Froggy and Darris.
This was only the second gearcase I've done. Pretty much the standard mods I'm told and it really did help the torque. Started out as a stock sportsmaster.