Hydro Junkie

Sorry RJ, but I don't even do that kind of sweet stuff for the wife. I do take her to Olive Garden occassionally, but none of the rest.
Now, back to engines:
No, I don't have a Fleabay account as I've heard too many horror stories of NIB stuff being thrashed junk. The reason I was looking at the K&B 21 is I was trying to stay away from the side exhaust set up. The .21 was an over the flywheel design which makes for easier set ups. I'm looking toward the .21 5 port as well, just haven't decided which way to go yet. If I were to go with a .18, I'd probably look at one of the OS engines. I know one has a water jacket and a pull start, might be an option as well, depending on hull weight and balance. I might go for extremely light and do some of the frames with 1/32 ply instead of the 1/16th. We'll see

toyotatruckin

OS CVRM is side exhaust but a good choice for power, the TZ is rear exhaust (as in exhaust exits opposite the carb) is air cooled and if it needs water cooling done to it either call me and Ill walk you through everything that needs done or send it this way and ill do it for you no charge except parts(only HJ on that no charge deal just cause I wanna see him get a boat built lol)

R.J. West

My ops .21 has a side exhaust and it fits perfectly inside the hull, I liked the way the header is designed and it in no way comes close to the inside of the cowl.

Hydro Junkie

I think, if I can't get the K&B, I would rather go with the NR 5 port. Add in a 3280 pipe in either case and we'll see how fast she goes when I get her done.

Blackout

The Novarossi 5-port .21 is physically allot bigger than my K&B .21. It looks like a .40 next to the K&B .21. This could be a packaging issue in such a old boat design, but the 180 degree header is real close to the side of the cylinder, so that will help. I can take measurements if you need them.

I really like that OPS side exhaust. That setup will be more compact than the typical 180 degree setup. Of course, an exhaust straight over the flywheel is the best for these sport hydros.

Hydro Junkie

Now you know why I looked at the K&B first. It's smaller size is what I really liked, along with the location of the exhaust. If I need to, I'm not against moving the engine back to fit the NR since my radio box will be up front. I'll be giving MECOA a call after they open, an hour or so from now, and find out what the word is on the 3.5 inboard. It would be kind of dumb for them to have the engine listed as available on the website when in reality it's no longer produced. I'll ldt you all know when I find out for sure

R.J. West

Yeah you know I'm disapointed about Mecoa Make me wonder now cause the website says its alvaiable. I need to get some .40 crankcase gaskets & some bearings, and they're the only place I know of where I can get them.

That ops .21 fits beautifully within the hull. The sides measure 3.25" wide and I dont think theres too many engine mounts that would work. The engine compartment also is not perfectly square either, rather its 3.5" at its widest and tapers down to 3.25 about3 inches forward towards the front. The Solinger mount was suggested here on this build by someone else, I looked into it and thought it was the best choice over the Dumas plate mount.

Blackout

If they are available, let me know, I doubt it though. Too bad a real company didn't take over K&B. I remember when you could actaully buy a good marine engine at your local hobby shop. Not any more... I would love if O.S. offered their front exhaust marine engines again. None of this converted car or ducted fan stuff....

Hydro Junkie

Okay Blackout, just for you. I called MECOA earlier today and found they are still manufacturing the K&B 3.5 inboard, it's just out of stock for a month or two. I'll be checking back every so often so that when I can get a delivery date, I can order three of them. Beats the heck out of pulling the engine just to run a different boat.

RJ, I opened up the Pak kit a few minutes ago and was met by typical dumas materials. I found the typical fair quality birch skin and the not so good mahogany door skin that had all been die cut. Two things did surprise me, pleasantly I might add. I found that the die cutting was cleanly done with this kit, unlike every other Dumas I've purchased. Second, and even more surprising is that the mahogany is, for the first time in my experience, actually flat. This is something new for me, but will make the parts even easier to use as templates. Sounds to me like it's time to get started on a major hack and bash build

Hydro Junkie

I just got a good laugh. I was checking the Pak's dimensions compared to the MHR and made a startling discovery. The kit's dimensions are actually almost an exact scale match for the 77 Atlas. The tunnel scaled up to 87" while the Pak tunnel was 80" and the Atlas was 88". The picklefork is a little off too, though not enough to really be noticable. To do an Atlas, I'll only need to move the center of frame 1 back about 1/2 inch. All in all, this should be an easy build, though I may still widen the hull approximately 1/2" across the tunnel for an Atlas build. More on that later

R.J. West

That '77-81 Atlas is a cool looking hull, all you have to do now is conjure up a cowl for it. That cowl is pretty much basic in design and should be relatively easy. I'm glad that Mecoa is in the process of making the k&b .21's. They should be taking orders on those now, right?

Blackout

HJ, Thanks for the info on the K&B .21 motors, I still wouldn't hold my breath on it.

Mecao supposely has K&B .91 inboards in stock for $360. I should call and order two for a twin rigger...

Hydro Junkie

I'll be checking back with MECOA next week, figure I need to keep getting updates. If I don't get an "availabliity date within a week or two, I'll probably end up ordering a NR .21 just so I can get the build really of and running. Since I have a source for the NR, it should be easy to get..

RJ, I started punching out the sponson insides yesterday. As per typical Dumas, the slots weren't as cleanly cut as the outline, meaning I'll need to go back and cut them out with an Exacto knife. Still, it's a much better job than the other Dumas kits I've had. I'll be picking up more materials today on my way home as the 1/16 ply I have is too flexible for the new sponson insides, at least after I get the lightening holes cut. Consider the build started and a thread to be started soon.

R.J. West

If your accustomed to working with aircraft quaility birch ply then be prepared for lots of sanding when working with the Dumas wood. It really helps alot to sand the parts while they are still in their carrier sheets to help make removing them easier. Sometimes, depending on how well they're cut you may have to run a Xacto knife along the lines. I use 220 grit sandpaper, it also cuts down on sanding later on in the build.

Hydro Junkie

I'm not going to worry about it too much. It's just a minor inconvenience. Anyway, I purchased more plywood on the way home and will be laying out the sponson insides and cutting them out tomorrow. My biggest challenge right now is to see how much modifying it's going to take to make all the cross frames line up properly. I also need to contact Speedmaster and Aeromarine about getting all of the running gear ordered. I want to get all the part numbers listed so others can get orders in as well since I want to make these boats easy to build for others too. Unfortunately, thought, I will probably do custom motor mounts as I don't like the way Dumas did theirs.

I'll bet some are some wondering why I had to go buy more material if I already had large sheets of plywood at home. I figure this is too flexible for the sponson insides since they serve as the boats backbone[X(] This is part of a sheet of 1/16th Finnish birch plywood made for homebuilt aircraft wing skins. It's capable of being rolled into a tube as small as 8 to 10 inches in diameter

R.J. West

If you look at the plans, the engine is mounted between frames 3 & 4. It measures 3-1/4" at frame 3, and 3-1/2 at frame 4.So that limits your engine mounting choices.

Hydro Junkie

Only in a stock build. As I said, mine won't be stock which gives me other options as well. That is another reason I'm going with different materials, so I can make changes. It's also one of the advantages in building a wood boat. I think you'll find my boat to be "unique", for lack of a better way to put it[X(]

Hydro Junkie

Actually RJ, depending on the engine I use, I may use rubber mounts to minimize vibration. I have them in all my other boats except one, and that was a "use what I have on hand" build. I may be retrofitting soft mounts into that one as well. I'm also thinking it would be fun to stick with a solid shaft. I've seen solid shafted boats that are faster than the same boat with a flex.

R.J. West

As long as the angle & prop depth is correct theres nothing wrong with straight shaft. Look at how fast the electric 1/10 scale hydros go over at Classic thunder, division I uses straight shafts. Those guys are running in the 40's.

As an idea, I am going to use the dumaswood blocks in mine. I've drilled out holes and inserted 8-32 machine screws thru the bottom and epoxied them in place. the holes were countersunk so the heads are level with the bottom, then they were epoxied in the hull. Cool thing is I still have room to mount the Solinger mount.
Theres nothing wrong with using a plate mount for your engine. I'm not the one whos going to fall into the belief that youmustuse a isolated rubber mount. I've actually gone to home depot and found rubber O-rings that work just fine if one wishes to go that route.

I would suggest considering using the wood engine blocks & plate mount. I believe this arraingment allows for greater flexability with changing engines during a heat, or for experiementing with different engines since some engines have different hole locations.
When i participate in races, i bring with me spare engines, abench grinder, battery operated dremel tool, power generator, etc, I dont like traveling , then to come across a stupid situation.

Hydro Junkie

Been there tried that. I found that it takes longer to change an engine with a mounting plate than it does to change and engine by itself. Once I get a boat set up, I rarely will change engines, making redrilling or changing mounts unneccessary. I've personally seen radios fail repeatedly due to harmonic vibration due to a hard mounted engine, yet the same hull with an isolated mount never had a problem. I've also seen a boat that couldn't meet noise limits pass just by putting in an isolated mount with no other changes. My first two Dumas builds had the plate/block set up, I was never happy with the weight or limitations on engine location. Not to worry, I'll have a few different ideas in my boats for you to check out. I might even go with a flex, just for the fun of it, that's still undecided

Hydro Junkie

Yesterday was a productive day. I managed to get all of my sponson insides layed out. Now just have to get them all cut out and start assembly

Hydro Junkie

Today was a totally unproductive day. No boat building was accomplished due to going to the NW Model Expo. Tomorrow I'll be at the Hydroplane show at the the Hydro Museum so I don't expect to get anything done then either.
Gee, is this thread dying oor what?

Hydro Junkie

Latest update:
I called MECOA again today and was told they only had a few more parts to machine to start assembling the inboard .21, with a rough due date of the first week of March. Needless to say, I'm not holding my breath.
I've labelled and punched out all the parts to my Pak kit, finding a few discrepancies. All are minor and cosmetic, but things I will fix anyway since I'm doing several mods to the boat. I found the top edge of the transom to be arched rather than flat, the twin tails mounted too far inboard and found the deck between the tails is at an angle and not flush with the main deck sections. As I said, all are cosmetic, but they will be fixed anyway

Hydro Junkie

Another day and more parts traced out. I'll be able to start cutting wood probably next week. I still have some fine tuning on some parts to do as I widened the hull to allow extra clearance for the NR .21's header, if I have to go that route. I'm still debating on how many other changes the boat's going to get, so more redesigning may be in the works yet[X(]

Hydro Junkie

I'm down to just frame 4 left to trace out and modify. After that, it's just the sponson sheers, but they wont' be done until AFTER the rest is epoxied together. I'm going to be fitting the modified frames together and make sure they all line up BEFORE I do any mixing of epoxy, that way I can use the first set as templates for the second Pak and Atlas. Hopefully I'll be able to start my build thread next week.
It sounds like there may be a Mini-Pak run in June of 2011. From what I'm understanding, we could have 3 Pak hulls at a fun run somewhere around the Chicago/Kalamazoo area. Having more would be even better, though I doubt Misshydro will drive that far, even though she says she's getting one to build. Anyone else want to join the possible Mini-Pak fun run?