Hello all,
Do any of you have pictures of you throttle and choke hookups,
I'm trying to figure out how to do it.
The engine is going into a H9 1/3 Cap.
BTW this is my first gasser.

Thanks,


John

Look on the RC Showcase site.
www.rcshowcase.com

I think Dick Hanson has some on his as well as hook ups for the cans. Can't get the link I have to work however.

Visit the IMAC site and look through the links. Great link page.
www.mini-iac.com

Bill

Hey John, glad you liked the standoff's. Here is the way I do it,
http://www.geocities.com/traviscouch/extra2.html
It has worked very well for me.
If you need the Fiber Optic to go along with it, give me a buzz.

Are you supposed to take of the throttle and choke arm on the carb and install the supplied arms?

John,
I used the original arms on mine, but not sure if you have the same on yours, never the less , it is not a hard thing to do, If you have problems, let me know and I will assist.

I removed the arms that are on the engine,along with the return spring. The replacement arms that come with the engine work fine. I would suggest you throw out the ball links as the supplied ones are junk. Servo city sells some 4-40 ball links with a 3/16" ball that work very well. Pop out the ball and press them onto the ones that come with the engine.

Leave the return spring (or at least part of it) on the shaft. Just unhook it. If you don't the throttle rod will vibrate back and forth and cause problems later (generally leaking around the shaft) which will make the engine either run poorly or quit .
Bill

excap232,
That is interesting, Mike Dooley at RC showcase recommended removing all the hardware from the carb. I'm talking the arms,return spring, the little black piece on the carb..basically everything. If you use the included hardware for the throttle shaft there is really no way to leave the return spring on since the collar(with the ball link) will not fit on the shaft. Mine is attached to the shaft with a set screw and loctite. I haven't noticed any looseness in the shaft infact my throttle linkage is rather tight. Has anyone else left the return spring in place??

If you put the included ZDZ hardware on, you CAN'T leave the spring. so on a suggestion from Dick Hanson, I cut a thin slice of gas line making a little washer and put that under the "wheel collar thingie" before screwing it down.


I am at the same point (putting a ZDZ80 on a H9 cap) and would also love to see setups. I like Roger's setup (thanks for the picture) and I used Roger's standoffs, and they worked great.

I'm ready to make servo mounts...and I would like to see other pictures....

David Soniat

This is what the throttle arm looks like now, the black thingy on the crankcase is the supplied arm. I'll probably take of the arm like you guys are saying . BTW the standofs work and look great,
Thanks aerografixs.

John

A clearer pic of the throttle arm as is right now

After having done a few more of these setups --I found some other methods which work well -if servo location and engine position cause questions.
First - cut off the choke arm end piece-
use the supplied arm ball link
make a bellcrank from a round servo wheel and position the choke arm so that it pulls easily and snaps to "off" easily.
On two models , I made the choke exit at aft end of cowl-on top!
The assistant places his finger on this rod and when the engine burps , he pushes the arm "in".
Done right - the engine catches and runs.
Don't put yourself at risk doing this!
(do as I say -don't do as I do)
The throttle arm , I attach to the existing end plate with a 4/40 bolt and nut and a copper tye wire to stabilize it.
Also - look at the geometry of the servo pushrod -
solidly position the throttle arm to provide a nice 50/50 throw , about center of throw.
Also set the radio to deliver 100% (aprox) of stick throw when the throttle moves 100%.
This may sound strange--but it permits the idle throw (trim) to adjust nicely from a high to a shutoff position.
The c/l of the throttle shaft to the c/l of the attaching ball link, is better if this measurement is aprox 3/4"-1".
The servo output arm will then have a output of aprox same length.
Result is a full , 100% throw
This setup, minimizes slop and bend losses.
Also remove the throttle stop.
Finally, setup the servo such that the servo PULLS to OFF.
Set max throw for open , just shy of a solid open position-to avoid jamming the servo when flying .

Although this is off subject, but it is the right audience, I thought I'd throw in this question. I too have a H9 Cap with ZDZ80 that is about done, and I'm about to mount the engine(I also have Roger's great standoffs). The question is, have all you guys mounted the engine vertically, or have any of you mounted it horizontally? (I know DH mounted his at a 45 degree angle just to be different ) If you do mount it horizontally, does the cowl have to be cut? It appears to be really close. Dick, why did you choose the 45 angle instead of horizontal?

Hmmm, I was just thinking that most people probably mounted vertically because most of the mufflers out there would be setup for that style mounting. I'm putting a KS can on mine and building the header, so I have the flexibility to put it either way. I figure the cooling would be better with the horizontal mount.

Thanks.

OK -the real reason I put the engine in at a 45?
Actually two reasons.
First - it permits the best, easiest header setup .
Secondly, it is the BEST setup for cooling.
Look at the picture - the air flows into the front fins - then it has to stay close to one side of the engine as it passes on by -
It is also low in the cowl- which permits instant flow out the bottom.
I know that the inverted is the easiest - with a in cowlexhaust setup - It will work - But I don't like that setup at all - too noisy -
and with some "mufflers?", lousy power.

Thanks Dick, that helps, and maybe I'll end up doing it the same way. Did you try to fit it in horizontally? It seems the cooling would be almost as good, but wouldn't require the cutting of the cowl. The header won't be too much harder to make, though it will require a bit tighter bends.

Have mounted the engine in all these positions
The 45 is by far the most simple setup and best airflow-

I am going to veer away from the subject a little myself but I am sure you guys have the answer. This is my first rear carbed engine and I plan on using the standoffs, but my question is, how far does the carb need to be away from the firewall? Or how much space in between?

There is only about a 1/4" clearance between the carb and the firewall, which is probably not enough. There is the stock hole that is in the firewall which should help, but it does not line up with the carb, so I plan to open that hole up to at least give the carb a straight shot back into the fuse. DH should be able to give a definitive answer on this.

"Giant Scale"
Mike is the one who told me (among others) to leave the spring on. EXCAP232

I rebuild for best results -and try to ignore the easy setup.
It is like buying a cheaper suit - --You may have
saved a buck but you will ALWAYS wish you had done the job right the first time.
The engine must get a full ,straight flow of air to the carb - so make sure there is a hole bigger than the carb inlet - behind it - OR keep the firewall at least a full carb hole dia away.

My favorite setup -for all my rear intake engines (and who would want any other setup?)
is a 1/4" plate mounted to the engine - then a standoff (boxing) back to the best place to attach.
So - the standoffs are all outside the engine bolt pattern.
In this case - cut a huge hole in the H9 "firewall" because the standoffs only need to attach to the edges.
What possible good is a big slab of plywood between the mounting points
Ballast?

EXCAP232,
I don't know how to mount the supplied throttle arm leaving the spring on--it won't fit. Perhaps are carb setups are different. Pukinbuzzard basically said the same thing-arm won't fit. I didn't use the washer under the arm may give this a try. There is a pic in the rcshowcase user gallery where the installer uses the stock linkage with the throttle servo right near the firewall. So I guess you can leave the spring on if you want.