Corky's Build

[Corky]

Thanks Ted this is the first all plastic fuel line connector I've considered using...In the case of my build the tank is now secured so I don't see the need for a quick disconnect but I do need one on the other mini so I'll give it a try on that one...I've run into trouble with any type of quick disconnect...Keep in mind my mini is in the water all season and the elements take their toll... This will be just one less problem on the new build...

[Corky]

Today I finished up the engine throttle cable brackets...I'm using a Teleflex Xtreme 30 series cable {4 inch travel}with 10-32 size threads as well as the teleflex balljoint kit for each end...These are quick release ends...I'm using an extension on the original 084 carb shaft bracket...And as usual I went overboard on the finished pieces...Polished 5052 aluminum .125 thick...Here's the detailed pics of the carb bracket and the throttle return spring bracket...

[Corky]

And here's an overview of the engine throttle assembly for this build...As you can see it's basically a direct route to the carb....The throttle cable is positioned so there's no hard angles or binding issues through the range of motion and moves quite smooth and easily...The return spring is a redundant feature and has only enough tension to idle the engine down in the event that the main accelerator pedal spring snaps or the cable or end components break...

[kent]

Looking good Corky ! I may have to put my sunglasses on, with all that polished shine !!!!
kent

[Corky]

Hey Kent ! Well, at least it's all behind me when I'm in the seat......

Next on the list was the battery box ...I'm not going to have any major items draining the battery so this build gets a small lawn mower size battery to keep the weight down{20lbs}...But even with that size I can get one with 420 cranking amps which is'nt too shabby...That should be plenty to spin the starter and run a few navigation lights...

Placing the battery seems like an easy task until I get to overthinking the situation......Away from the fuel tank...Check........ NOT under the fuel pump or lines just incase there's a leak...Check...Centered in the hull....Check...And lastely, below the prop line so it's not an air obstruction....Check...
Which pretty much places me under the engine twards the back...And I want it up off the floor in case I crease the bottom...So...That pretty much places itself !!


Now that the main location is picked I wanted to keep it simple... 1/2 inch conduit did the job...Light,strong, and added bracing for the engine stand..

The battery box fits snug right in the framework and the battery box strap will do the job of holding it down....

[Corky]

I have a question for anyone who want's to give their experience or opinion on this issue....Here's the mufflers I'm using...They're harley mufflers I snagged off an Ebay auction.. 50 bucks with the clamps and heat shields !!! Anyhow, here's a breakdown of the internal pieces...The baffle which has a plug in it so it's not a direct "see-through" baffle...And the fiberglass matting that gets wrapped inside the case....Which pieces, if any should I reuse ??? I was thinking of cutting the baffle down to just the end cap and using that {?} Would this be too loud ??? The mufflers themselves are a beautiful piece but kind of heavy with all the internals in place...
Any input is appreciated...

[Corky]

So with the mufflers gutted I had the chance to mount them in their new home... I drilled holes through the casing and used a stainless bolt on the inside and a captive nut on the inside of the 1/2 inch emt mounts...If I ever need to remove them all I have to do is pull the baffle and unbolt them...I thought this was the best looking option of all the ideas I had...

[Corky]

And as a teaser I'll throw a pic in of the headers I'm in the process of building...The primary tubes are at the magical 32 inch mark that Chuck{Airboatpros} has suggested is the optimum length ...Too bad this is'nt a dragster I'd just turn them all up and say to heck with the mufflers !!! ...

[aerokirk]

Corky,

Here's how I determined how much back pressure I should have in my exhaust system which I took from the 4A084 specs. I have a manometer so I was able to measure the pressure directly. You can build your own manometer with some clear tubing, a ruler and a mounting board.

5.6.5 Exhaust system. The back pressure of the exhaust system, includ-ing the muffler, should be measured 2 inches behind the manifold outlet in the exhaust pipe or muffler inlet pipe applied to the engine and shall not exceed 20 inches of water at WOT and maximum governed speed of the end item.

Hope this helps in your decision on how to baffle the mufflers!

[Papee]

I have the Harley mufflers on my boat. I removed the guts and welded a washer in the end then "tuned" the opening size sort of like the dirt bike expansion chambers. I didn't really notice any difference in noise once the washers where put in.


the headers on my boat are the first set Chuck made. They are stainless.

[Corky]

Thanks for the info guys...I'm thinking I must have misunderstood Chuck on the length of the header tubes...Looking at mine tonight and looking at what Chuck has sold in the past it looks like mine are way longer than his ... So at this point I'm not sure what the 32 inch increment is supposed to be......

[Papee]

He and I talked about it. He uses a formula for the length so I'm sure you got crossed somewhere. They should be like either of the boats I did. The green boat I just used 3/4 conduit because the tips for the heads I cut off the original exhaust are a good fit.

[Corky]

Papee, After investigating your threads,Aerokirks ,and a few others I'm sure my primary pipes are too long.. I'm going to shorten them up to what fits the boat nicely{not too much really but some}...I'm using 1 inch emt... I chamfered the original exhaust pipe ends and the 1 inch slips over the pipes with a little help....At the 32 inch mark the pipes do fit where they need to go but there's only about 4 inches between the muffler and the header for the flex pipe to do it's job {which is'nt enough in IMO}..I need to keep them equal lengths front to back,side to side for the first test runs{just like a competition header}...Eventually I'll experiment with different header designs hence the reason for the EMT...
The fitting for the O2 sensor on each side is going in the collector...And I'll take a reading as Aerokirk has outlined to see where my baseline readings end up on the backpressure...

[Corky]

I've run across a header primary tube calculator that I've added to the formulas forum...And believe it or not the tube length is right around the same length that I wrote down from my notes talking to Chuck......In any case I've taken 3 inches off the original 32 for a total primary tube length of 29 inches...This does'nt include the collector in the equasion just the primary length...The tubes are equal lengths just like a drag header..Eventually I'll be trying different variations on the headers but this is the starting point...I'm waiting on the O2 bungs and plugs to come but here's the system to this point...I did'nt want a bunch of clamps cluttering up the build so all pieces are completely welded other than the muffler inlet...The flex pipe ended up with a 6 inch piece between the header and muffler..There's plenty of potential movement if the engine mounts need to move........Again, the primary pipes are 1 inch emt and the collector is a 2 inch inner/outer pipe.... That got cut down so only about an inch of the 1 7/8 flex pipe went inside the coupler and in turn got welded...The header and flex pipe are now taken off as one unit from the muffler...The muffler is a 1 3/4 inlet so the flex pipe end goes from 2 inches down to the 1 3/4 inlet to the muffler...As with the engine stand,the primary tubes are "in line" with each other so the prop only sees one obstruction

I ended up with a nice, clean run from the header to the muffler ...

[Corky]

Moving on to the fuel system...I modified the 084s' original 45* fuel pump fitting...I enlarged the passage,machined the inlet from the AN fitting configuration to a concave,radiused design to smooth the flow coming from the Attwood flexible 3/8 fuel line which is now clamped on the fitting...The fuel filter is located near the tank and can be easily serviced{through the access door} even with the deck in place...The primer bulb is located where I can reach back and give it a few pumps when needed... I flared some pieces of 1/2 inch EMT and tacked it to the rigging in various places...The marine fuel line fit perfectly through them...

[txriverrat]

Corky
All my life I ran a machine and steel fab shop. Your workmanship empresses me ,great job.
Ron

[Corky]

Thank you Ron, I appreciate the compliment from a guy with your experience..
I'm trying to build a reliable,nice looking boat that should last for years...It's tough working full time then coming home and trying to make some progress...One nice thing about that is I have enought time to think about different ways to accomplish what needs to be done...I'm old enough to realize I'm better off taking my time and engineering it well than to rush through the build just to be burdened with going back and fixing stuff....

I need to be honest, the thought that I may be going into too much detail and taking up the site's space with this build has crossed my mind more than once so if anyone else has this thought I apologize... I'm just trying to give other people some ideas with their builds at any level they can accomplish it...

[txriverrat]

Just keep on doing what you have been doing ,I know I sure enjoy the detailed reports.
Ron

[Corky]

Well, OK then....

I wanted to work on the muffler baffles today so I can cap off the pipes...I don't want any moisture or insect issues before the build is complete ....Strangely enough here's what I found with the baffles...I'll throw this pic up so you can see what I'm refering to... I assumed the baffle end pipe would have quite a bit of holes leading up to the exit...Seeing the outer screen would lead me to believe this is the case...But in fact the area with no holes is where the plug is...This keeps the muffler from being a "see through" design like a glass pack...Anyhow, the only holes in the end pipe are a series within an inch on either side of that plug{basically the solid section of the screen} !!!! The hole run from the end of the muffler up to the plug is solid except that inch of holes !!! I was taken back a little thinking about how the gasses need to travel to get out of that muffler and the backpressure it must create in the name of noise reduction...

I ended up cutting the pipe and welding it to the end cap as seen in the pics...There were no welds holding the end pipe to the cap so I needed to join the two...I'm going to leave the end caps as they are now and run the engine ...I'll check the pressure and add the washers papee has suggested to tune the system if needed...

[Corky]

Time to throw up some pics of where and what I'm using for this build as my instrument panel...This was no easy choice let me tell you...There's just so many choices of locations,materials,shapes, etc...I really like Papee's forward mounted instruments for ease of a quick view and reach...But I wanted to be able to walk from the front deck right onto the platform and into my seat with the front seat detached....I like the side mount panels but I still wanted to be able to just glance down without having the gauges too far down and to the side...So....

I came up with this design...I used an angled panel on the side.....This one is ABS with UV inhibitors in the mix, it's very light and has a detachable bottom... it came from Classic{Panther} airboats...

I've got a Tac, CHT gauge, oil temp, oil pressure,volt, and hour meter and the toggle switches{and eventually a power anchor} so I did'nt feel I could get away with a smaller unit...Now with a quick side glance I should easily see the tach and CHT...Not high enough to get in the way,not low enough that I have to look too far from the operators view.....
I see some builds have a grab bar at,in front of, or around the instrument panel...When I visited Kent I saw he placed his on the outer side of his panel and uses it as a grab bar if needed for that side of the boat...I thought that was a great idea... So I made up a grab bar that now has the best of both...It can be grabbed from the side or the front...Another nice feature with this design is I can grab it while in the seat to steady myself if need be and the outer section will keep me from landing on the panel itself if I get rocked{?} around....


So without further explanations/reasoning here's what it looks like to this point...