MrMikeG

I know the feeling, just fired up a cat I bought 14 months ago, the longest build ever! Was like a little kid waiting for sunday to come around. [sm=wink_smile.gif]

martno1fan

Looks good mate as regards batterys get a 6 v hump pack one with the big cells not aa that way your battery wont drain too quick.Also put a shaft saver on your flex cable between the motor and the tube i use a zipp tie its just in case the collet comes loose so you dont lose your prop and shaft etc,you can buy ready made shaft savers but a zip tie works for me.Good lucck with your maiden hope she runs well for you.
Mart

nooh

Crikey Mike thats a long time, bet you were glad when it was finished.

and Mart will do on the battery's thanks, also I have a shaft saver laying around somewhere just can't find the bloody thing my boat shed is like a junk yard.

nooh

Installed the new pipe today, had to trim the radio box a bit, ?????? it will look OK when all is finished, also a New battery pack and S/S which I finally found,, And the muff sticking out the back.







Lots of fiddly jobs to do yet, but the main gear is now almost complete.

MrMikeG

Don't forget floatation! How are you going to seal your radio box now? Get some black vacume tube and split is length wise, run it around the hole in your transom to cushion your muffler, looks cool and helps absorb the vibrations. You can get a gromet from Clark Rubber but the vacume line is easier and comes in handy for other jobs too!

nooh

Noodles will be the last thing to go in m8, I put RTV silicone around the top of the radio box ???? Just need to clamp it down tight now.
As for around my muff was going to do something like I did with my Rio, Had a Radiator hose laying around the same size as the muff, cut about a 20ml length then wacked her on then used RTV silicone to seal the hole in the transom, waterproof and absorbs the vibration like you say m8.


Um now Im stuck.. Was told with this engine my tuned length of the pipe should be 12 and 1/4 to 12 and 1/2 inch ??????? being a 2 inch belly where do I take the measurement too, from the pipe header to where???????????????????? Do I measure to the pipe center, or the beginning of the 2 inch bit...
bit confused on this one . any help would be appreciated

Thanks.. Henry.

wayneuk01

you measure to the start of the band on the pipe "the end of the first cone "

martno1fan

Yea just make sure they included the bend in that header in the measurement as some of our american friends measure in a straight line from the centre of the flange to the band on the pipe which can be confusing .Usually i measure to centre of the 2" band thats where i was told to get the measurement for mine but everyone does it different which is what gets confusing .
Mart

nooh

Thanks Wayne and Mart, Mart If you measure to the center of the band then theres a 1inch difference between what wayne says. I was told 12 1/4 to 12 1/2 inch in length, So that 1 inch difference would mean a lot in power .. I think.. [&:]

martno1fan

Exactly my point so find out where the person that gave you that measurement measured to and from and if he accounted for the bend in the header .I was told a similar thing on my hydro so measured round the bend which is the correct way i was allways told because diff headers give diff performance and turned out i was way out as he measured in a straight line so my motor didnt rev out,but as soon as i moved it 1 1/2" it ran great.Its knowing where the measurement was taken and what header thats important here because 12" on a deep vee header in straight line is diff from 12" on a 90% header.
Mart

viperhulls

Henry, don't cut it till you give it a run, it is easy to cut it off at the lake but it is hard to put it back on. Just do it bit by bit until you are happy with the proformance of the engine and check the rpm with a taco. If you haven't got one you can borrow mine, is it going to be going for this sunday?. We will all be at nudgee beach this sunday at about 7:00am till 11:00 or 12:00. Hope to see every one there, should be good with the big tide.

rcboateric

Henry, read this article before doing anything, it would help you a lot to build your boat in the correct way.

http://www.modelgasboats.com/Magazin..._Conquest.html

nooh

Thanks Mart, I knew you had to measure the curve in the pipe as well and not in a straight line. Don't want to stuff this bit up, bloody pipe cost $300au to buy.

Tony, Don't think the boat will be ready come Sunday will have to pass I think, Thanks for the offer on the taco but maybe next nudgee outing I might stroll up there.

Eric , thanks for the link, after reading it its about the same way I built my boat but didn't tell me about how to measure a 2in band pipe. ?????

This is the email I received from Daniel at Omen Engines

Maybe should email daniel and ask him where on the 2in band does he take his measurements from..[&:]

rcboateric

Henry, the best pipe length for the top speed is 11-1/2" measured from the center of the flange straight back to the center of the band. Your mod 260 could be turned into a prop at around 18000rpm in the water and there could be lots of vibration in the boat, I suspect how secure your pipe mounts like that.

martno1fan

That would depend what header he uses wouldnt it ,this is why the safest way is to measure round the bend of whatever header you use but then the measurement will be nearer what he was told .Waynes pic is the correct way to measure the tuned length.
Mart

rcboateric

The problem is no matter how he sets up a length for the pipe, the pipe length would be changable by the pipe that will move back and forward once the motor starts, I'd use a pipe stopper and pipe mount to mound the pipe stinger from the outside of the transom.

martno1fan

I dont think hes done setting it up yet Eric ,but i agree a pipe stop is a good idea,that said if he makes the pipe a snug fit and seals it at the transome that might be enough on its own.
Mart

rcboateric

And the pipe stop only works good with a steel header pipe, I just don't realize if it has the choice to not mound a pipe at the transom for most secure and you still can use the cowl on the boat.

MrMikeG

Measure along the pipe to the back cone, 12 1/4 to 12 1/2. It is the back cone that tunes the pipe.

nooh

Thanks everybody for helping this is great.

I rang Daniel from Omen engines who done the Mod, and he told me exactly what you said Mart measure from the center of the 2" band back to the end of the flange and going around the header (not straight) With his mods he find it best to start at 12 1/2 in then go from there, he told me I would most likely end up at 12 1/4 which would be ideal for my Cat.
So I will start from there and see how I go,,


Eric after I set up the pipe I will measure straight back to the center of the band and see what measurement I come up with.



I forgot to order the pipe stopper when I ordered the pipe but have one being sent to me now, Also got a taco coming as well.
And Mike went to Clark rubber to get my noodles, and saw the grommets you suggested so got one of them also, might look better than old radiator hose

I want to make a better throttle set up so will post pics later on, getting there. Thanks again everybody.

nooh

I asked BH Hanson for some info regarding there pipes and this is what they sent me.

Marine Exhaust System

When assembling exhaust flange, be sure to lubricate the o-rings liberally with light oil or grease. If necessary de-burr the inside of the flange so the o-rings won’t tear during assembly. When assembled, the tuned pipe must be fastened securely and not be moved right or left from its natural position or the o-rings will leak and may cause engine damage. A good test is to blow into the water line at the rudder while pinching off the exit fitting and listen for air escaping through the exhaust pipe or at the header. Water leaking into the engine from the exhaust can damage the engine and make starting difficult. Make a habit of looking for the water from your exit fittings when your boat passes by to make sure you haven’t picked up something on your rudder or water pickup blocking water flow. Burned or melted o-rings are a major cause of your engine suddenly running poorly. This also leads to header damage.

Length of Exhaust
Measuring from the engine side of the first exhaust flange, follow the contour of the header down the middle to the widest part of the tuned pipe. A pre-measured piece of coat hanger wire that’s bent to follow your system makes a nice permanent measuring tool. If you have a 2 inch or 1 inch band pipe, measure to the center of the flat. WHAT LENGTH YOU CAN RUN YOUR EXHAUST SYSTEM WILL DEPEND ON HEADER TYPE, ENGINE SIZE, LEVEL OF MODIFICATION, HULL DESIGN, PROPELLER SIZE AND AMBIENT TEMPERATURE. Wrap to center and Deep Vee headers work best with our RPM or Shortie pipe and should be run with the pipe as short as possible. 231’s run better with the RPM pipe and a starting point of 13 inches. Stock 260’s run well with the RPM pipe set at 12 3/4 inches and 2 inch band pipe at 12 1/4 inches. Push the pipe in 1/4 inch at a time until you feel you’ve found the right combination for your hull and engine. After finding this, trim off the extra header inside the tuned pipe leaving at least ¼ past the inner o-ring for a seal, or 1/2 inch in case you think you’ll need to pull the pipe longer again.
Modified 260’s using the cone to cone pipe should start at 13 inches in length. Again, exhaust system length depends on hull type and which engine you have. The 2 inch flat band or 1 inch flat band pipe on a modified 260 will run well in the 12 1/2 inch range. START LONG AND CUT SHORTER.

Which ever way you chose to measure your exhaust length, make sure it gives repeatable measurements results as pipe length is a major factor in getting your engine to run its best.

There is no warranty on our exhaust system when used with in conjunction with exhaust parts other then ours.

martno1fan

Good to know your getting good advice ,at a guess ill say Erics measurement is right where you will end up ! measuring in a straight line that is .As Bh Hansom told you its best to measure the pipe length including the header bend that way no matter what header you use you will find the correct length consistantly,you will however need to fine tune to the setup your using and the conditions too.Trim the header 1/4" at a time and start long and go shorter till you find the sweet spot ,you want about 1/4"-1/2" of header past the last o ring on your pipe when your done cutting.
Mart

nooh

Thanks Mart, My Cat nearly finished just waiting on the pipe stopper and want to do a few more things to the Jordo, But if all goes well will be in the water next week-end.. Then will learn how to set it up right.

rcboateric

The pipe stopper only works good with a steel header pipe cauz the alum header pipe is a bit too soft and can't hold up a stopper that good when it gets hot. A new boat needs the time and patience to become a nice or fast boat, theres a lot of the things you might need to adjust such as prop height(strut height), the best balance point of the hull, a right prop choice, carb needles setting, prop walk correction and etc.

nooh

To right Eric, Building the boat was the easy part now like you say setting it all up right will be the hardest part. Hopefully end of the week the boat will be finished and I can start having fun also Tomorrow am picking up the new prop you suggested and a new balancer as well. Thanks again..