Scycraft F1 Tunnel w/ Evinrude Xflow

[evilrude 1]

why dont you put a v4 case on that x-flow and swap out the prop shaft to a 15 spline for better prop selection.

[mwe14]

What would be the advantage of the v4 case? Are you talking about putting a 15 spline Merc prop shaft in it? It's my understanding that the splines are about an inch shorter on the OMC prop shafts and to to run a Merc cleaver (or any merc props) I would have to drill some out of the hub. I haven't seen much/any OMC cleavers for sale, maybe I'm just looking in the wrong places.

I was also told that the OMC lowers don't ratchet, and the props act like a brake when you let off the gas. Was advised to stay away from them for good reasons (stuffing)... Which is the main reason I have been leaning towards a Merc case. That and they seem much more abundant and easier to get parts for.

[evilrude 1]

The advantage of a v4 case is the narower diameter and by swaping out the propshaft I ment a v6 omc shaft (very little work required to do this) or you can run the 13 spline sst60 style cleavers with a stock v4 shaft but you might have a little problem with enough pitch.

[mwe14]

Do the v4 cases ratchet (freewheel when you suddenly let off the throttle in forward)?

I have heard that the OMC v6 cases have a hard time and don't hold up all that well in surfacing applications (which this certainly is), and the cases still crack occasionally even with the carrier pinned because of all the added stress on the case and gears. How do the smaller v4 cases and gears hold up when surfaced?

These aren't really issues (as far as I know) or concerns when running a sportmaster or cle.

[evilrude 1]

The v4 gear case does not ratchet and isn't as strong as the v6.
Never knew the merc speedmaster ratchets

[mwe14]

You are correct, the speedmaster is a direct drive and does not ratchet, but I am talking about the sportmaster (full size shiftable case) that as far as I know does ratchet, like the regular style merc lowers.

[1BadAction]

Forget about the motors, etc. What happens when this guy blows this boat over and is knocked unconscious while strapped in?

Tunnels like this are kept on the race course for a reason. This is a bad idea all around.

[Da Bull]

I don`t know what the intent for this boat is but in this thread you have been schooled in all but one area. Thats where i come in. Your gonna blow up that cross flow. If you turn it up beyond it`s stock rpm recomended by OMC it will blow up. We tried everything in the 80`s and nothing worked. I watched the best cross flow racers there was (Wilbur and Wayne Weeks, Jerry Cain, ect) and they all blew them up on a regular basis. We were told that you have to be a rich man to race a cross flow OMC and later we found out what they were takling about so save yourself some money and buy a looper if your stuck on OMC or buy a Merc. I know you say you arn`t gonna race it but thats what they all say. Tunnel boat, Finger ports, capsule Yep, Your gonna hot rod it. Be careful and take it slow.

Search safety capsule and read about all the bad things that can happen in them when testing alone. Your Dad won`t always be there.

DB

[Capt.Insane-o]

Not being one of the resident super experts on this board, I do have an older Burgess F1/Champ/120/WTF you want to call it and went both ways with it. They don't go I'm not going to go very fast well, they are meant to go "fast". I have a #6 and #4 for it, and have run a cle, sporty and a xr6 case on it. The xr6 case was the least offensive, but does'nt have enough skeg area, and is weak. Going out and riding in it is fine with a helmet, sub 70 mph, few blurps here and there to show off. Cool.

You will drown if no one is looking after you and something bad happens.

You have an RPM limited motor, which means taller pitch props, which means a big paddling wheel effect trying to run a full size case. You have a nice boat, put it back in the race trim it was made for.

[mwe14]

Da Bull, that's interesting, and the first I've heard of that problem. What lets go in them when you start turning them faster? Stock these engines run max rpm around 6000 I'm pretty sure? When I bought this I was told it should turn around 7000rpm. Is even 6500-7000rpm pushing it? What did they turn them to when racing?

[mwe14]

I haven't committed to a larger case, I'm just trying to figure out all of my options and the pros/cons of each one. I got the xflow for a pretty good deal and wanted to use it pretty much because it's what I have. Don't have anything against Merc or OMC, it's just what I happened to buy.

If I end up going Merc, I think I may have a line on an older style (hydraulic trim in/out and manual up/down adjustment) 12" mid for a good price, and know people who race F1 boats here (their shop is about 20 min from where I live) and could find a speedmaster lower if that's what I need.

Just thought if I could get a decent set up and keep cost down it would be a win-win. But it's sounding more and more like a champ style mid and speedmaster is the way to go.

[Da Bull]

What lets go in them when you start turning them faster?

Pistons, Pistons and more pistons. I have a pile of burned up cross flow pistons.

[mwe14]

Ok, I found an older style Mercury (hydraulic trim in/out and manual up/down adjustment) 12" mid for real cheap with steering wing plates, and as long as it is in good condition I am going to buy it. I am starting to hear from more people (here and off the forums) that the crossflow is the wrong engine for this application unfortunately, so it looks like I will be selling the powerhead and midsection (should be able to get my money out of it, $1200, pretty much everything is new including all the electronics, which were 1400 alone, solid mounts, flex flywheel etc etc) and looking for a merc 2.5 power head, probably a 200 or so to start, and a #6 speedmaster. Right hand if I can find one.

By the sounds of it, this should be a much better set up, and will also allow me to switch powerheads in the future if I want.

[Dave Strong]

Ok, I found an older style Mercury (hydraulic trim in/out and manual up/down adjustment) 12" mid for real cheap with steering wing plates, and as long as it is in good condition I am going to buy it. I am starting to hear from more people (here and off the forums) that the crossflow is the wrong engine for this application unfortunately, so it looks like I will be selling the powerhead and midsection (should be able to get my money out of it, $1200, pretty much everything is new including all the electronics, which were 1400 alone, solid mounts, flex flywheel etc etc) and looking for a merc 2.5 power head, probably a 200 or so to start, and a #6 speedmaster. Right hand if I can find one.

By the sounds of it, this should be a much better set up, and will also allow me to switch powerheads in the future if I want.

Now you talking.

Dave

[Fibertron]

call the guy you bought the boat from,, he has everything you need to get it set up safely