Another BFN Rebuild

No, but if I could find one big enough, Id slap it on. I suspect that little 11.5x15 2-blade that we tried on the Tique is better suited to the lighter boats that can get out of the water- but who knows. Since that prop seems to be comparable RPM-wise to the small boat props (12x13 OJ and 12.5x12 Acme 3-blades) due to its smaller diameter and minimal blade surface area, I suspect it will be waaaaay too small on a big block.

nice sound!

wow that a dirty neutral!

Tim,

Enlighten me...wouldn't a 14" diam. prop get a better dig for the cavitation issue?

The more blade surface, the better, when it comes to avoiding cavitation (so I would think) so yes, a larger diameter prop might help some. An increase in pitch seems to be more effective though- the 12.5x15.25 612 cavitates less than the 13x14 and 13x13 wheels.

No room to run a 14" prop though... the original 13x15 Federal was within 1/2" of the hull and left a lot of gel and rudder port damage. The 13" diam Acmes offer a bit more since their blades are raked back a good bit- but still less than 1". Starting somewhere around '81, CC notched the keel aft of the strut (by ~5/8") to allow the use of the 14" props. Most 454 BFN's made after that point came with 14x14's.

We added ~5/8" of glass to the inside of the hull in that area in case we want to notch the keel. But I'm not overly eager to tear the boat back apart just yet. There aren't really any rh 1" shaft props any bigger in diam than 13" in the sizes we're looking at, anyways.

15x12, that's crazy. That's a tiny prop for 450hp, even for a 1:1. I'm guessing that's a v-drive with some kind of reduction to boot?

Tim, I'd be interested in what you figure out. I have long term plans for the 67 BB that I have. We are looking at a build that will put out similar HP numbers to your 454. I thought that Mastercraft put out a 14x18 RH prop for the powerslot but I was mistaken. We have one of those lying around and they are LH.

The current setup on my 67 is actually LH. With the scarcity of the BB in those days its possible that Correct Craft put out a few LH rotation boats. I might be inclined to leave it LH. I was going to convert but sounds like it could be a bad idea? I think my prop on the 67 is a 13x16 but I haven't looked at it in a while.

Slap a 1.23 to that bizzzoat and then you can run standard rotation parts

Tim, Awesome project ....That motor hits like a muscle car! (A sound we all love) You did an awesome job....as explained through the thread the research, design and selection of engine components is as much work as the build if not more and it is nice to see it come together as planned. Very encouraging!

A few more updates and lessons learned as we enter spring of 2013...

1. The cavitation noted above was actually transmission slippage. A fresh rebuild this spring solved it, as well as the terribly dirty neutral shown in the video.

2. On/off nature of the secondaries is now resolved as well. As discussed here, we swapped to a different secondary diaphragm housing (with a pressed in brass insert) and went 2 steps heavier on the spring (white to purple) and we can hold any speed we want.

3. As Ive said a few times when people consider foamless stringer rebuilds, any drain point is also an intrusion point! Found a battery box mostly full of water this spring, so we emptied it. 10 minutes later, its full again. Strange, considering the boat was on the trailer... in the garage. Turns out that the (now drain-less) battery box was the low point every time the boat was stored on the trailer and lift (boat sits a bit nose-low) and thus, a good portion of the water that made its way into the boat drained to the battery box rather than the bilge. The bulkhead on the front face of the batt box (shown below) that was originally meant to be a drain point *just in case* any water made its way under the floor, did just the opposite and let water in instead. Apparently the o-ring seal doesnt quite work as advertised. ~40 gallons of water later, the boat seems to ride a bit higher in the water and has picked up a few mph. So, not all bad news.



For now, we'll just be more careful to keep the nose higher when the boat is stored... but on future rebuilds, a few things would help prevent this from happening. Installing a battery box drain is one of them. Moving the drain access point to another (higher) location is another.

TRBenj wrote: ~40 gallons of water later, the boat seems to ride a bit higher in the water and has picked up a few mph.

What does that make your top speed now? 65ish?

JoeinNY wrote: About time Dave, Tims been waiting all week for someone to ask that question

Someone else sort of quasi kind of asked that question earlier this week. I was going to provide what I believe was the answer based on a conversation Tim and I had at WL, but decided it was his place, not mine, to provide. Still true.

My guess is he's had the picture all loaded up on photobucket ready to link since monday morning.. and that he has a while before he has to look over his shoulder for another bfn.. .

Apparently Larrys info is out of date.. thats what he gets for leaving early

Larry, your a couple shy... more like where you get your kicks....

Tell us about how it handled at those speeds?

Ready to hunt down some big rollers on Green Lake again?