About as fast at half throttle than at full throttle

[Jerry Wyss]

OzBryan on here had his Top21-7M O/B conversion going fairly well yesterday with an OS 20J carb and stamped Irwin pipe on it. It was on a HTB290 also. It's just starting to make the right noises! Looked like a good heat racing set-up. Maybe he could give you some feedback on prop / stinger diameter etc.?

"As luck would have it!" :lol: Favorite saying I have used over the years.

 

[aaron alberico]

In the next couple of weeks will be doing

back to back to from my 35plus to T-7M nova's

and let you know,

regards Aaron

 

[Mike Larson]

I just threw the carb inquiry out there...... J Dub, you'll solve the animal..... keep at it..... Rod gave me the 220, and i'll work it up in a few days.....

thanks aaron, post what he's using if you can, narrow down some parameters..... Mike

 

[ozbryan]

Jerry Here are some details from my boat.

HTB290/OS leg nova 7m 20j carb used on 3rd channel no needle in carb. From set up board to bottom of the bullet just under 5mm pipe is an Irwin stamp and it's long ATM about 10inchs from plug to rear of the cone.. Neutral on the leg angle and head is at 6thou if I'm remembering correctly.

I will be trying other carbs and pipes and shortening the pipe up too. I found the boat to run nice at this leg height not sure if your having any issues there.

Oh and the prop is an ABC 40x53 with 2mm of cut back.

Hope you get that baby sorted!

 

[Jerry Wyss]

Jerry Here are some details from my boat.

HTB290/OS leg nova 7m 20j carb used on 3rd channel no needle in carb. From set up board to bottom of the bullet just under 5mm pipe is an Irwin stamp and it's long ATM about 10inchs from plug to rear of the cone.. Neutral on the leg angle and head is at 6thou if I'm remembering correctly.

I will be trying other carbs and pipes and shortening the pipe up too. I found the boat to run nice at this leg height not sure if your having any issues there.

Oh and the prop is an ABC 40x53 with 2mm of cut back.

Hope you get that baby sorted!

Thanks Bry, If I have that motor height right thats a bit higher than mine, about 2mm.

The 10 inch pipe length as you stated has me a bit baffled. Mine is at 8-3/4" right now and it has been from almost 9" down to 8-3/8" and back out a few times.

The 40X53 I have is one I bought here a while back and as I found out it has been reduced in Dia. Among the group of B/C 1440's and the 40x53, the 40x53 ran the best. I'll have to score a new one and give it a fair shot.

I have been at .004" H/S for 3/4's of its running time on 30% and opened it up to .006" recently. Its obviously has been running in "tractor" mode almost all this time, with a couple events of wanting to lay down and purr but it was brief and weak.

I look at the sleeve and I can tell this thing ain't designed to run in tractor mode at all. Looks like its gunna be an Old fashioned Suthern Oregon Turkey Hunt! gawd I hate direct drives

 

[ozbryan]

Jerry ill re check the motor height tonight on some glass.. that was off my wonky old ts2 set up board and ill let ya know.

Im running 50% and the prop is not reduced in Dia.

It sounds like i definatley have the motor higher than you do though.... :huh:

 

[Tim_Duggan]

Irwin stamp and it's long ATM about 10inchs from plug to rear of the cone..

It didn't look that long to me, are you sure about that distance and are you measuring thru the centreline of the bends? Or was that was to the rear of the rear cone, where the stinger starts?

 

[ozbryan]

Yeah rear of rearcone...

Might be a stupid question here JW when you pull half throttle on your radio is the carb opening past half way??

 

[Jerry Wyss]

Yeah rear of rearcone...

Might be a stupid question here JW when you pull half throttle on your radio is the carb opening past half way??

Well, up front, this top motor hasn't been doing that "as fast at half as at full" deal

all along. It got to a point where it was doing that as well as another o/b I have.

I have this radio and throttle set to where I have no "back", or "brakes" like in car/buggy set-up. But it does look like half on the trigger is just beyond half on the barrel.

Hoot, I think I got it figured out, I'll just put a Thunder Tiger carb on there and It Has To Go Faster :lol: :lol: