Nova 45 DD going lean?

[Tom Foley]

All ears on this one . Have had similar issues and wondering whether to put a new uncut needle in it or a different carb on it . Need to test some more .

 

[Tim Kish]

All ears on this one . Have had similar issues and wondering whether to put a new uncut needle in it or a different carb on it . Need to test some more .

First going to move the needle right up front to shorten the lines as much as possible, although the old motor ran fine where it was and if that doesn't work Carb change is next, running out of things to try.

 

[Ray Sametz]

What's the inlet hole dia. on nipple to carb ????

 

[Tim Kish]

Carb is completely stock Ray, couldn't tell ya it's a friends boat.

 

[Ron Jefferson]

Fuel delivery is what I believe is the problem. I've seen Olly's engine run a couple times now and the richer you make the needle the longer it goes before it starts to surge. I believe it got 4 laps into the race before surging the last time I seen it run. At the Dashwheel race we hooked it up to a small plastic tank and the attitude of the engine changed totally.Better throttle response, engine ran cooler and started easier. Not sure what moving the tank forward accomplished but I'd go with a small hopper as close to the needle as you can with a main tank as close as you can get to that. And, you might want to try what Jeff Schindler suggested and get the third channel off the engine mount and try a remote without third channel capabilities so my friend stays off that little dial at the top left on the transmitter.

 

[John Beardslee]

I second getting the 3rd channel off the motor mount if that's where it is mounted.

Thanks, John

 

[Tim Kish]

Fuel delivery is what I believe is the problem. I've seen Olly's engine run a couple times now and the richer you make the needle the longer it goes before it starts to surge. I believe it got 4 laps into the race before surging the last time I seen it run. At the Dashwheel race we hooked it up to a small plastic tank and the attitude of the engine changed totally.Better throttle response, engine ran cooler and started easier. Not sure what moving the tank forward accomplished but I'd go with a small hopper as close to the needle as you can with a main tank as close as you can get to that. And, you might want to try what Jeff Schindler suggested and get the third channel off the engine mount and try a remote without third channel capabilities so my friend stays off that little dial at the top left on the transmitter.

Agree 100% Ron when we added the 1oz hopper the engine instantly sounded better .

Als boat has the needle on the tub and vibration is not a problem .It ran fine with a different motor.

We are going to test using an old OS remote needle right at the carb next, like the old days .lol

 

[SayMikey]

How about throwing the motor in another boat,that will tell you where the issue lies

 

[dwilfong]

What is the spray bar ID and carb size ?

What is the ID of the crank hole?

 

[bsmtboy2]

I run the same motor but different pipe and have not had any problems yet. I would look at the needle mounted as a suspect . The o rings could be worn causing the issue. I would also check your pipe pressure fitting and hoses.

 

[coolhotrods]

You said there was larger fuel line on the tanks,but did you change the size of the Cooper in the tank? This would cause a fuel draw problem. Had this happen myself. Dustin

 

[Terry Keeley]

Terry

Check the spray bar and make sure that it pointed the wright way. I had one it was facing the wrong way.

Dave

Spray bar is cut in Olly's motor, straight in hose.

What prop are you running? Just asking is there a oring at carb bottom in case?

Been all over with props small to big. Put a 1455 with a little cup and it was fast when it ran, motor's strong when it's not lean. Not sure about the O-ring, Olly went through the motor again and said he couldn't see anything wrong.

Fuel delivery is what I believe is the problem. I've seen Olly's engine run a couple times now and the richer you make the needle the longer it goes before it starts to surge. I believe it got 4 laps into the race before surging the last time I seen it run. At the Dashwheel race we hooked it up to a small plastic tank and the attitude of the engine changed totally.Better throttle response, engine ran cooler and started easier. Not sure what moving the tank forward accomplished but I'd go with a small hopper as close to the needle as you can with a main tank as close as you can get to that. And, you might want to try what Jeff Schindler suggested and get the third channel off the engine mount and try a remote without third channel capabilities so my friend stays off that little dial at the top left on the transmitter.

Third needle is mounted on the hull so that's not it.

Fur shur fuel delivery is the problem but it seems abnormally finicky about tank location, line length etc. Olly has a long metal tank with internal hopper but the hopper is at the far end so fuel goes twice the length of the tank (6" or so) before it gets out, I'm sure that's part of it. That with the largish (11mm) carb sitting up high can't help.

Starting to also wonder if the motor is sealed well and not leaking past the front crank or PTO seal...

 

[Ron Jefferson]

Terry

Check the spray bar and make sure that it pointed the wright way. I had one it was facing the wrong way.

Dave

Spray bar is cut in Olly's motor, straight in hose.

What prop are you running? Just asking is there a oring at carb bottom in case?

Been all over with props small to big. Put a 1455 with a little cup and it was fast when it ran, motor's strong when it's not lean. Not sure about the O-ring, Olly went through the motor again and said he couldn't see anything wrong.

Fuel delivery is what I believe is the problem. I've seen Olly's engine run a couple times now and the richer you make the needle the longer it goes before it starts to surge. I believe it got 4 laps into the race before surging the last time I seen it run. At the Dashwheel race we hooked it up to a small plastic tank and the attitude of the engine changed totally.Better throttle response, engine ran cooler and started easier. Not sure what moving the tank forward accomplished but I'd go with a small hopper as close to the needle as you can with a main tank as close as you can get to that. And, you might want to try what Jeff Schindler suggested and get the third channel off the engine mount and try a remote without third channel capabilities so my friend stays off that little dial at the top left on the transmitter.

Third needle is mounted on the hull so that's not it.

Fur shur fuel delivery is the problem but it seems abnormally finicky about tank location, line length etc. Olly has a long metal tank with internal hopper but the hopper is at the far end so fuel goes twice the length of the tank (6" or so) before it gets out, I'm sure that's part of it. That with the largish (11mm) carb sitting up high can't help.

Starting to also wonder if the motor is sealed well and not leaking past the front crank or PTO seal...

Pretty sure the third needle is mounted to the engine mount rail unless Olly changed it's position.

 

[Tim Kish]

Terry

Check the spray bar and make sure that it pointed the wright way. I had one it was facing the wrong way.

Dave

Spray bar is cut in Olly's motor, straight in hose.

What prop are you running? Just asking is there a oring at carb bottom in case?

Been all over with props small to big. Put a 1455 with a little cup and it was fast when it ran, motor's strong when it's not lean. Not sure about the O-ring, Olly went through the motor again and said he couldn't see anything wrong.

Fuel delivery is what I believe is the problem. I've seen Olly's engine run a couple times now and the richer you make the needle the longer it goes before it starts to surge. I believe it got 4 laps into the race before surging the last time I seen it run. At the Dashwheel race we hooked it up to a small plastic tank and the attitude of the engine changed totally.Better throttle response, engine ran cooler and started easier. Not sure what moving the tank forward accomplished but I'd go with a small hopper as close to the needle as you can with a main tank as close as you can get to that. And, you might want to try what Jeff Schindler suggested and get the third channel off the engine mount and try a remote without third channel capabilities so my friend stays off that little dial at the top left on the transmitter.

Third needle is mounted on the hull so that's not it.

Fur shur fuel delivery is the problem but it seems abnormally finicky about tank location, line length etc. Olly has a long metal tank with internal hopper but the hopper is at the far end so fuel goes twice the length of the tank (6" or so) before it gets out, I'm sure that's part of it. That with the largish (11mm) carb sitting up high can't help.

Starting to also wonder if the motor is sealed well and not leaking past the front crank or PTO seal...

Starting to wonder that myself, will check tonight after work.

 

[Chris Wood]

terry

sounds like bearing seal issue to me.. seen it with several motors over the yrs.. same stuff. we also had a similar issue yrs ago when we had a needle valve to far away from the carb. but you said you tried various needles so unless they where are in the same location that is out.

i am sure you have checked pressure fitting not plugged. tried a different tank just for grins?

just throwin out ideas

chris

 

[RonShaw]

Have you checked the bearings? How old are they? Bad bearings could be the issue. I also had a front bearing on my NR 46 with enough excessive wear that it was causing the crank to rub the housing between the front and rear bearings and giving me a very similar result. Being an OB, lubrication on this bearing between runs is extra important for me.

 

[Rudy Formanek]

I once had an OPS 67 in a mono that had a smallish tuned pipe pressure fitting (MACS thin wall straight), would go down the straight rich and would immediately go lean when I gave it rudder for a turn, wouldn't even make it to the second buoy. Change pressure fitting, BINGO ran well. Yah, I know big stingers are supposed to be the best, but I usually go with the smallest I can, until performance really suffers. Maybe cause I only circle race.

 

[Rokieboater]

I had a carb stop screw break off. The boat would start and idle rich, go out and run about a lap and then act lean. Took me 5 runs and a pitman to notice the carb was sliding out a little and sucking air. It was in a SGX rigger so things were tight and the carb barrel never fell out. I know you guys are smarter than me but it did happen so I thought I would throw it out there.

Did you check the pressure line for any holes?

 

[DON MAHER]

Terry, I had the same problem with my sp-40 two tank system. Solved it by raising the 1oz hopper tank so the outlet was the same height as the carb inlet. Still not sure why but it worked for me

Don

 

[Tom Foley]

Having a very similar problem with an engine(Nova 46 DD ) that has less than 1 gallon through it but exhibits some of the same symptoms . All this stuff seems to pop up every couple of years with one engine or another for all these reasons like " wrong head clearance , spray bar too small , wrong pipe or silencer , blah , blah etc , etc . , except the VAC 91 , Mac 67 , Mac 84 , Mac 45 . Just basic good designs I guess . It seems kind of improper that someone basically following all the rules that have been so successful for scores of engines has to go through this frustrating , expensive hazing .