ENGINE & ADJUSTMENTS.
I've decided to go with the Greyhound 6.5 hp, 3/4" shaft 'Honda clone at Harbor Freight. With all the brick and mortar stores and internet options, the next closest in price was in excess of $179. The decision means I'll have to modify the muffler placement, since in its current position it'll impede on the recently purchased Trac-Vac blower housing, causing engine damage, or increase vibration that could ruin the impeller or engine shaft.
Please take a look at below for errors on my plan to modify the muffler placement when have a chance.
Muffler Modification/Repositioning
I'll need to move the muffler up and out of the way and want the results to: 1) not cause stress damage to the engine block by either coming in contact with the blower housing or engine; 2) being too heavy/bulky, or; 3) the assembly isn't supported properly. The pipe size will fit the existing mufflers' outer diameter versus inner so as not to interfere with performance or create excessive back pressure.
Required Tools
Drill and 1/4" bit
Center punch
Large file
Steel wool/Sand Paper
Pipe cutter (hacksaw)
Required Supplies
2 x 1/2" copper tubing (excess for trial & error)
High heat epoxy (ex. JB weld)
Pipe wrap / Fiberglass Tape (3 1/2' or wide enough to cover the seams in case my high heat epoxy doesn't hold up)
Preparing the copper piping
I'll cut the 2' of copper tubing to approximately 7" (I'll have three tries at). The initial choice of 7 is: 5 for length, and 1(x 2) for overlap. This will result in avoiding a second attempt or being unable to cut later if the intake and exhaust of the muffler are too long. I'm going to try to make sure this is the only time I'll need to cut the tubing. I'll find the correct height/clearance by lining up the muffler, once cut, with the 5" copper piping and place the piping in the middle. From there, I should be able to eye up the height I want. Again, I should want the muffler pipes to overlap the copper pipe by at least an inch after I've done so I'll add 2" for overlap.
After cutting the pipe, I'll make sure both ends are perfectly flat. I assume this will be important when setting up the epoxy later. If the pipe has a perfectly flat end, I can simply stand it up in epoxy and wait for it to cure. If the end is not flat, the pipe could lean to the side and perhaps not match up or keep proper clearance between the muffler and blower housing. To ensure a true end, I'll use a file to clean it up. If perfectly flat ends are not a major concern due to the existing muffler weight, the epoxy takes too long to set up, etc? I'll just lay propped up on its side or in a vise.
Preparing the Existing Muffler
I'll cut the manifold on the existing muffler past the bend in the elbow to provide the right clearance relationship between the muffler and blower housing. The mistake I want to avoid is to simply cut the muffler tube in half before continuing. This may result with difficulty in marrying up later of the intake-extended exhaust-muffler being far too long or the angle of the existing manifold bend being at the wrong angle. I figure the best way to create the correct angle/height is to place the piping in the middle. Once cut, I can eye up the angle and height. As a backup plan in case I fudge the angle, I want the copper pipe length to be able to be long enough to perhaps bend at least an inch after done (see above where I'm adding about two inches to the pipe length).
Testing the assembly (before epoxying)
I assume a good way to test that I don't create additional restriction is blow into it the pipe as hard as I can or use an air compressor. Then, hold my hand over each end of the assembly and try again. If I feel any more resistance with the end plugged by my hand than I did without, I'll need to redesign.
Epoxying it together
Epoxying the original manifold end. The first thing I'll do is epoxy the original manifold end to the pipe, then bolt on to engine and line up the blower housing's position. This'll be my last chance to make sure that the pieces are level, the muffler is low profile enough in relation to the engine, and to allow the muffler to sit properly prior to epoxying the copper pipe and manifold.
Epoxying the pipes. Since the epoxy can make up for mistakes, this does not have to be perfect, but the better I line this up now the less of a headache it will be later.
Epoxying the muffler end.
I'll slide the two sides together after lining up the pipe/manifold assembly to the muffler. If the muffler bottom falls flat onto the copper pipe, I should have it down pat. I'll pull the assembly apart again, make sure I'll double check that the pieces are level, and the muffler doesn't come in contact with the blower housing or engine.
I'll then ensure to have plenty of epoxy between the top of the copper pipe and bottom of muffler and press it together. As well with the first bond, I want to make sure that the fittings can't break loose and damage the engine or turn the muffler modification into a machinegun when running.
I'll make sure to liberally apply epoxy to the copper ends of the pipe to the top and bottom of the cut muffler assembly to ensure that its� air tight. After the epoxy has cured, I'll test the seal by plugging one end and blowing into the other as before.
Fit and Finish
I'm usually the only one who picks up on the little 'ditzels or mistakes I make along the way, but if there are any final steps I've missed-please advise.
The muffler may need extra support, which could be accomplished with cleverly placed bolts, hose clamps or pipe support straps. Once I see in operation, I'll think of where the forces are transferred and adapt as necessary.
I'll probably dress up the exhaust tube and add a margin of safety with a bright coat of high temp paint on the cover to avoid anyone coming in contact with.
I originally thought to purchase an aftermarket Honda clone muffler with the correct bends and clearance, but when I saw the prices; my budget can't afford a $100+ muffler on a $130 engine, plus I don't want a muffler that looks like it should belong on a small car.
Optional Ideas
1. One alternative I've thought of is to take the copper pipe, cut two 1 slit opposite each other on each end, then use hose clamps/u-shape muffler clamps on each end to pinch the three piece assembly together. Drawbacks could be lack of 100% seal (fiberglass tape); short lifespan since under vibration load from engine and working around yard, or; assembly comes in contact with engine or blower housing.
2. An additional alternative of perhaps using flexible steel braided hose (flexible exhaust pipe) to connect the cut apart existing muffler pieces to relocate. Drawbacks could be difficulty in fabricating a way to secure to the engine assembly; having hose available in correct diameter; and ensuring I can seal the braided ends in a permanent fashion.
3. Another alternative is using electrical conduit?
