20 cal craft with ops 3.5

[tmunn]

I have purchased this boat and installed a 3.5 speed with rotary carb.I got a few runs but then broke the con rod.

I have a NIB 3.5 speed that had the turbo head and buggy(slide) carb.I took the head button off my broken 3.5 and put it on the new engine.

So now i have basically a new 3.5 ops speed that will take the standard plug.

I did get a couple runs with it before the con rod broke.It seemed to be plowing the water or heavy in the front.

I tried the x437/3 and she did not want to sing out like it should.

I tried the P 215 and she revved up much better and was doing o-k till the rod broke.

I have no experience with mono's what so ever but i assume it should Ride with a slightly nose high attitude and fly across the water and not push through it.

I have my new .29-40 ops pipe set at 8.5" and it seemed to like that.

Do you think there are any decent speeds attainable with this older engine or am i beat before i start it is new?

What props would you recommend to try?

Thanks guys.

Terry

 

[redracer]

Kick your strut out as much as possible and try a 440 3 blade and depitch it a small bit see how that works Robert R&R Racing

 

[tmunn]

I have that prop i beleive and can kick the strut out no problem.

I will try that next time out...

 

[Duck899]

Have you checked the bottom of that calcraft? Place a straightedge on the bottom from the transom to about 8-10 inches forward. Calcrafts were noted for having bad bottoms right out of the mold. If its nice and flat, it will fly, If it has any hook or concavity at all, it will plow water, no matter what you do.....This will be part of the reason for the weak rod breaking in the OPS.....It had alot of load on it pushing that hull through the water.....

I've seen Calcrafts around here that needed filler all over the bottom from the transom to about 8 inches in order to straighten them out.

 

[tmunn]

I will check the bottom for sure tonight but the previous owner said that it worked and ran very well.I think it is more my setup.

I have not messed with the prop angle and see it ha a fair bit of negative i beleive it is called.Back of the prop lower than the front.

i get my neg and pos mixed up still...

 

[tmunn]

I checked from the transom and forward 8" in several spots and it looks really straight. and flat.

I think my issue is prop and or strut angle.The previous owmer had a nova rossi and perhaps had to run the boat flatter to keep the front down.I have a much less powered engine with the 3.5 ops and perhaps i need to adjust the strut to get more of boat up on plane ?

I will make some adjustments next time out.

Thanks guys

 

[tnrcboatracer]

I consider prop end of the shaft lower as negative. I've never run negative on any of my monos, only neutral or slightly positive. I will put a little negative tab on them (never more than 1/16") to settle them down if the nose wants to fly too much. Lead in hte nose would be another option to get the CG a little further forward if the boat is really light. Where is the CG as a % of length with your setup (balance pt from transom/overall length)?

 

[tmunn]

It makes more sense to me to run neutral or a sligh bit positive as well.

Is it correct to balance the boat with an empty tank ?

The tank in this boat is 12 oz which seems like a lot of fuel / weight in the nose.

Where should this boat balance .It is 33" long cal craft.

 

[tnrcboatracer]

The balance point depends on the hull makers design. As I recall, the Twincraft type hulls, which the Calceaft is, typically balance around 30~35% from the transom. The Seaducer hulls are more like 35~40% from the transom. For the Calcraft, check with Lenny at his web site.

 

[tnrcboatracer]

double post

 

[tmunn]

I got a lot of the bugs worked out today. THen it started to rain .I kicked the rudder back raised the strut and put on a x440/3.

I sealed arounds where the stuffing tube exits the boat and maybe i should not have now the water that gets in cannot get out <_<

Do some builders leave this hole unsealed on purpose to let the water drain.I do that with one of my hydro's

Man that little boat came alive.DEFINATELY on the right track.

She just has a slight porpus when she tops out and a little side to side action which i beleive is my trim tabs..

Thanks a lot for the help so far guys.I am having engine issues now and am going to post a thread in the general section.

Terry

 

[tnrcboatracer]

Yes, most folks leave the shaft exit open to allow the water out. The only down side is that the hull will also fill with water if it dies on the pond. I prefer my hulls to float high so that they are easier to see if they go dead during a race. I've recently tried something new; I seal the stuffing exit and install a 5/32" eductor nozzle on the right side of the keel at the stern. The eductor has a loop of fuel tube that goes above the waterline to keep the hull from filling with water when stopped. I epoxy a 5/32" aluminum tube to the stern with the end 1/8" above the hull bottm on the left side of the shaft tube. It seems to work very well so far. I'm slowly retrofitting my mono fleet to this concept.

 

[tmunn]

Back out sunday afternoon and i lenghtened my pipe and was not nearly as hard on pulling out the complete plug element.

I removed the silicone from my strut where it exits the hull.

The water would not come out and the boat was being weighted down.I have no auto bailers.

tnrcbaotracer

I like your idea and may contact you for a picture if i keep the mono and get it working better.

It is my first one and so far like the speeds of my Hydro's better.I bought the mono to try in rougher water when it is too rough for the 20 hydro's.I am going to stick my valvola or mac 21 in to see how that works out....

It is a fine line between being too heavy on the nose to porposing.I may have to make finer trim tab adjustments

I have contacted lenny and am waity a reply on balancing point.

Terry

 

[Jerry Muro]

We had a racer in our district who ran this combo and it ran very well. Please look up Dave Neelman disrict 1 NAMBA he is our club president. He can be reached on our web page under NAMBA disrtict 1. Jerry

 

[tmunn]

thanks jerry i just dropped him a line.

 

[David Neelman]

Jerry....Thanks!

Terry, (I also e-mailed this to you along with photos).

I ran this boat for a few years, and loved it. Very stable and quite fast. It ran very flat and stable.

I ran the Blue Head OPS Supermarine w/ rear exhaust however, not the side exhaust model. GREAT engine, and parts are available readily from Remy at Aeromarine Laminates. The side exhaust model should run real strong however.

For head clearance, I had it squeezed down to around 10 - 13 thousandths, running 65% nitro. Gotta use high nitro in the .21s....they LOVE it. The motor screamed. I found that 21s need to be "just right"....not much room for error. Make sure your bearings are also top notch and in good condition.

For a carb.....I used a an OS 20G that originally came on there OS Max RZ-M engine.......awesome carb...I use OS on all of my OPS engines...great combo. (OS 8B on the OPS .45 and .67 also). In addition, I recommend a third channel needle control. Very essential. I use the OS In Flight control right on the carb. in place of the regular needle, or... if no room in the smallish CalCraft hull, mount it on the side on a block off the stringer, or use a Kalistratov unit available from Al Hobbs. I found that you need to run the motor just right......not too rich, not too lean...just a touch too lean, and it will die, where larger motors may stay running. The third channel is handy so you can get it screaming, then back off a click or 2, to a slight "gurgle" in the pipe pitch.

Pipe: It sounds like the pipe you have is an OPS 4280 possibly. It's a little large, and if I am correct...it won't let the .21 motor crank out the RPMs that it is capable of. I ran one of 2: An OPS 3280....AWESOME pipe (again...Remy at Aeromarine Laminates can help, or Al Hobbs sells a Kalistratov knock off of this)....cranks out the RPMs, or an Irwin QRE Shorty Quiet Pipe. Unfortunately, I don't remember the length as I recently just sold this boat, but when you get good RPMs in the straights......shortening it a little at a time, until the motor comes off pipe in the corners, is the point where you go back out until it holds the pipe in the corner. Try to get a used pipe to play with and cut up...then duplicate the length on a good one once done testing. Naturally, run a pressure line from the large section of pipe, to the tank vent.

If you are pulling the plug element inward toward the piston.......you are running strong.......a strong .21 can do this....just richen a hair, or add a thin shim to the head.

Prop...the defacto standard for this and many other 21 monos....the octura X-440/3, 3 blader. Stock...it should run great.

I ran surface drive right out the back...slightly off center to comp. for prop walk. The shaft exited the hull as low as possible. The strut (Don Gardner XXL...avail from Rum Racing's Lenny Blake), was tilted just a hair.....back end slightly higher than the front...talking approx. 2 degrees.

Trim tabs....home made versions of Speedmaster tabs. Down just a touch on the inside tabs.....outer tabs just about flat with hull.

Turn fins on both sides at corners of transom.....hanging on an angle equivalent to the vee angle of the hull.

One 8 oz. tank in front of the motor.,....just under the deck, and an additional 2 ouncer on left side next to the motor (only because I would run out just before the end of a 6 lap heat w/o the side tank).

I hope this helps.

By the way.....we have more in common...I also have an Aeromarine Thunderbolt w/ a Z-260 (Hanson Hornet)...I LOVE IT!!!!!

Dave

 

[David Neelman]

Terry....the e-mail I sent to you bounced back......said it was "over quota"....could have been all the photos I sent...they were quite large.

Let me know and I'll re send.

Dave

 

[tmunn]

e-mail back at ya..thanks a ton...

I will make some changes asap and try that.