Riggers from Japan

[Ian Inverarity]

Tim,

I dont particularly like the stock venturi on the CAM 45, I also think it is too long, and too abrupt at the face. I noticed the Andy Brown versions of the motors had shortened bellmouths. Also I noticed Scott Young's 45 SG was quicker, he said the only thing he did was shorten the bellmouth!

I will aim for something that looks a bit like yours! 8)

The clearance cant be helped, it is to clear the tank tray in a 40 Seaducer. Not my boat anyway...

Ian.

 

[TimD]

I think all the current CAM motor's carbs look a little odd. The 45's are known to suffer from some fuel draw issues. The 67 green head get's a boost from shortening the venturi too.

Wish I could find that damned formula for venturi design

 

[Ian Inverarity]

Tim,

The version of the green head 67 that I have has a fairly short venturi now. However the shape is a bit abrupt. My motor is superseeded now, and I haven't even run it yet! :

Ian.

 

[Hammerhead]

You guys seem to know what your talking about more than most people around here do. I took some pics of what you guys did to the 9B and showed some of the guys at the pond. Most thought it was for looks, and the people who have used them before say, the sound just makes you think it is faster. Hmmmm!

Let me know how it goes with the Picco. Have you run it yet, Tim?

 

[Twin_k90]

hmm wounder what this sound is that these guys are talking about?? i havent noticed any different sound changing venturies and stuff,

Dale

 

[MikeP]

I followed this thread on another forum about 3.5 carbs. Look down the posts you will find the topic change to bellmouth intakes.

http://www.rcboat.com/cgi-bin/yabb/YaBB.pl...91325885;start=

-MikeP

 

[Hammerhead]

Like I said, earlier Dale, They sound like a vacuum cleaner with an engine running in the back ground. At least the ones I have heard. The one on the Picco doesn't seem to be flared out much as the ones I'm used to seeing, though.

Hammer

 

[Propjockey]

Anyone used one of these venturi inserts?

 

[Propjockey]

polishes nicely

 

[TimD]

Let me know how it goes with the Picco. Have you run it yet, Tim?

Hammer,

I have run it but I made too many changes at 1 time to measure any differences.

I am not happy with the entry to the venturi - i think I messed it up a little and the bellmouth is not "flat" enough.

The damned arm kept coming loose on the 9B barrel too, so it has had the loctite treatment. I think that was part of the reason why the boat would stop on the 4th lap all the time at the nationals. The 9b with the main needle removed is a much nicer fit in the SG than the Picco carb! I need to do a lot of "thrashing" at the pond before the next big race. I'll keep you posted.

 

[Hammerhead]

Thanks Tim!

Got a lot of people interested in your 9B. I showed some pics around. When you get it down to an art, I will pass on the details.

Hammer

 

[Twin_k90]

Marty,

Ian would like a 9B for his K90, do you still have that other one that was stuck up??

also the order is nearlly ready for shipping, just waiting on the trim plates,

Dale

 

[Hammerhead]

How many do you want! Mr.Shimizu, Throws them away. If I can, I will send them before they hit the can. He changes them to 7Ds for the Long Distance race boats, because he say, the 7Ds have a better upper end response. I tend to agree with him, because the 9B has almost no change between 3/4 to full throttle.

Hammer

 

[TimD]

Hammer san,

Please don't throw them away - throw them to Dale and myself for some R&D and we will send you back the finished product.

They are too good to waste!

 

[Twin_k90]

ah ok, i think with the bell mouth the 9B is the stuff, i will fit two to the twin as well, the exhaust throttles are getting a bit messy, i would like to go back to headers and carbs,

send us one and we will bell mouth it for you marty, then you can do back to back runs and tell us what you like and we will make them suit you/

 

[Hammerhead]

Gotcha Dude! I will see Mr. S in a few days, so I will get as many as I can.

Hammer

 

[Twin_k90]

Sweet thanks dude,

BTW i passes the titnunium pipe around at the nats, there is some intrest there from a few people, espically when i stod on the heder end and it didnt bend!!

Also me and ian are running our pipes way short now, we think you can shorten yours right up now, ill email you the measurments we were running!

 

[TimD]

Short pipes are the way to go with the K90's.

Ian and I convinced Dale to try back to back the pipes long with big props verses short pipes and a smaller prop and the thing was easily 1/2 a second to 1 second a lap faster every lap for 5 laps that we timed. that might not seem like a lot but when the laps were around 14 seconds each thats a big slice.

 

[Twin_k90]

yes tim you were right, i will get some more power and away we go!! with the big props as well!

 

[Ian Inverarity]

Dale,

Keep the revs up! ;D

Can you get the XXL throttles like Wild Bill uses? They never gave me any problems, but I only used 21 and 45 versions. I was impressed by how long the single motor ran on when the other one stopped, so they seem to make the engines a bit more reliable.

TimD,

My K-90 would have been a lot more impressive but for an assembly problem. :-[ It chewed the brass flywheel collet and stuffed the bearings. :-

Hammer,

The response problem can be fixed by using exponential on the throttle via a computer radio. This can work quite well.

Ian.