Very tempted....

Thanks for your info on oil mjohnst3

Hi Dave,
That's one of nicest Waco's I've seen! I ran my 7-35 today and it runs very smooth for about two minutes then slowly dies. I'm running 10% Klotz KL-200 oil mixed with 90% methanol. I'm using four 2400mah nimh (1.2v per cell) wired in parallel to give 9600mah's for the glow plugs. The Saito carb seems a nice upgrade but I'm on a learning curve with getting it adjusted correctly. So far I've followed the 7-35 manual on break-in settings for the low and high speed needles. I think that my glow battery begins to loose power after a couple of minutes and the rich mixture can't continue to run without strong glow plug power. I noticed when I was burning the remaining fuel in the engine at the end of the runs for the day, that the engine ran really well as the mixture began to lean out. I don't want to run it lean for the first few hours as I've read in this forum where engines have been ruined by running them too lean. It might be wise to get the McDaniels onboard glow system to break in the engine but it's heavy and I don't want to add the extra weight to the Waco. I would use it for break in only but that's pricey for only three hours of engine ops. The carb adaptor from CH Ignitions seemed to be a good fit for the Saito but I did put high temp silicone around the exterior circumference to preclude any possibility of an air leak around the carb (see picture). I sent Adrian a picture and update on his adaptor recommending silicone around the adapter. I'll let you know when I run the 7-35 next and the progress I make.

Lairs, can you tell me your settings again for the Saito carb referencing the high needle setting and low needle setting when you installed yours? Also, the picture shows the installed adaptor from Adrian. Thanks guys.

Ed

Hello Herc!

I appreciate the report on your break-in procedures! Wow ~ it looks as if it will take some patience only running it for a couple of minutes at a time before the glow battery runs down!

I was going to wait until after my engine break-in to see how it ran without any on-board glow. If it has trouble at that time keeping all cylinders operating I was considering the McDaniel's 7-cylinder on-board glow - but I note that they cost about $150.

One question - What is the Saito carburetor model number that you have on your 7-35? Is it the one that fits the Saito FA-129r3 (SAI90R3821)?

Here’s hoping that your break-in session goes well (and enjoy the sounds).

–DJ

PS: Thanks for the Waco comment - replacing the stock decals with some from Callie Graphics never fails to improve the looks!

Ooops!

I meant the Saito FA-120r3 carburetor

~ sorry

--DJ

Hello Ed!

Well, I knew I shouldn’t have gotten on the computer so late last night! In my confusing message above - my real question should have been the following;

> Which Saito carb are you using on your 7-35?

is it the Saito FA-120r3 (SAIE120R3)
~ or ~
the Saito FG-90r3 (SAIEG90R3)

Thanks for your help (boy do I need it!)

--DJ

hello Dave
The position I have the main needle.
Is from the closed open 2 turns.
And idle needle rich set at the factory.
Then it will try 1/4 turn at a time.
Lars

Hi Dave,
I'm using the FA-90R3 carb. Lairs had indicated in an earlier reply that both Saito engines use the same carb and I'm sure he is correct as horizon hobby listed the same part number for both engine a while back. You can look on the web for a parts breakdown for both engines and verify part numbers. At the time I just ordered sub assemblies to make up one carb because they were on back order so long. The part number for the throttle barrel assembly is; SAI90R3-87, High speed needle valve; SAI60T85, Carb body assembly; SAI90R3831. All ordered from Horizon and cost about $10 more over ordering the full assembly. The above assemblies come with o-rings and assemble to be a complete carb, no additional parts needed. I worked on my engine some more yesterday and I think my ignition will last at least 30 minutes as I made a better ground by attaching it to the engine case rather than the engine mount. I'm getting a hotter plug now. I'm going to give it a try again this week and hope the engine will run a little longer. I might be buying the McDaniels system? I think Horizon has the full carb back in stock now. I'll let you know how the next run turns out! Be careful, the FG90R3 is the fuel version carb not the glow version you'll need which is FA90R3 engine components.

Ed

Lars,

Thanks for your reply. I keep asking the low idle needle setting because I bought all the seperate components to make up the Saito carb and the low speed needle wasn't installed, I had to put it in myself and I adjusted it 2 turns out as stated in the 7-35 manual. The Saito manual has a stock setting of 3 turns out in the FA90-R3 manual. Since yours runs so well I wanted to know how many turns out from closed position you are at. Thanks Lars!

Ed

Hello Lars & Ed!

Great information from both of you ~ thank you very much!

–Dave Johnston

These engines run much better with nitro. 5% is enough. Your engine if slowing down and quitting can be two things; 1. too lean but I doubt this. If the idle needle is too lean the engine will slow down and stop at mid throttle with the old carb. 2. so rich the plugs load up and quit with fuel slobbering out the exhausts. Do not be afraid to play with the needles with the engine running. At high throttle, lean out to full rpm and then back off to 500 or so rpm less. An unbroken in engine will be fine run up to full power with the needle for less than 5 seconds. Then your needle will not be ridiculously rich. You need to train yourself listening to the engine under different needle settings. Now the idle. Throttle the engine down to a reasonable speed like 1800 rpm. Adjust the idle needle opening and closing to hear what the engine is doing. Get it to idle reasonably steady. After a couple of hours with 10 minute runs start dialing in with lower idle and higher leaner settings at full. With a fully broken in engine the top end is STILL set fully for highest RPM and then richened to slow down 200 or so rpm. The idle as you adjust down to lets say 1200 rpm will require readjusting the idle needle. It is critical to keep all wired as absolutely short as possible and thick. You are dealing with 1.3 volts and even the slightest resistance drops the voltage a lot! -Tom

I went to Toledo and I was disappointed that Horizon was not displaying the Evolution radials. The correct carb as of the new batch in stock is the SAI90R382-1 -Tom

Thanks Tom for the explanation on needle settings. I'm wondering now if my idle needle is set too lean as it's slowing down at mid throttle and stops with not a lot of fuel slobbering out of the exhaust. Think I'll try to richen it up some. I'm worried about breaking in with any nitro per the manual but if you've had good success doing so during breakin then I'm up for using 5% nitro. My wires are short and fat for the ignition but I think my ground wasn't the best. I've now connected my ground wire directly to the engine case and getting a much better glow on the plugs. I'll run next time per your instructions. Thanks again for your assistance! Ed

looks like I need some parts for this engine. HH doesn't sell them and UMS/india seems a long ways/time away...anyone in USA sell the parts? im in certain need of rings and maybe orings (intake/exhaust tubes). it'd be nice to know a source for the cam rings and cylinders, too. i'd also like to get a tool to remove the heads at some time (to replace cylinder without replacing head).
.
how's correspondence with UMS going lately? I noticed their website is "under construction"

[email protected]
Here you go Pretend. -Tom

Hi All,
I figured I would add my 2cents worth since I have finally gotten my 7-77 in the air. I have read the entire forum and followed Toms advice on limiting the throttle travel on the stock carb to about 70% and have had no problems achieving proper needle settings.
I am using a McDaniels on board glow driver that is set to come on just above idle. I have a very reliable 1200 rpm idle with good response from the engine and am getting about 4800/5000 WOT .
I have run both regular glow fuel with up to 20% oil and run the alcohol blended 50-50 with 5% cool power.
I actually seem to get a better run using regular glow fuel over the blended . The high speed is backed down 2 to 3hundred rpm from max and the idle was adjusted for a good transition . I am running a 22" x 12pitch prop and it pulls the plane with authority .
These engines are definitely different to run than a regular glow engine ! But are really worth the effort when you hear them fly and idling back to the pits is a real treat .
I have also noticed that they seem to like flying over being run on a test stand .
Just my 2cents worth and YMMV .
CzDaveC

Dave, congrats! Sounds like you have things in control. Be sure to thoroughly flush that engine out! after the days flying with air too oil.

7-35 engine guys,
I've run my radial with the Saito carb now 9 times and it's running very well (each run has been without issue at all). I'm still breaking in the engine but it is beginning to run reliably. The adapter for the carb was leaking air around the outer circumference due to not having silicone around the perimeter on first install, hence the reason why it would run for a minute or so and then slowly die as I opened the throttle. I'm still running on methanol and Klotz oil for another hour but it's now running without the need for constant glow power and idles at 1500-1600 rpm without dying. It turns over with just a quick flip of the prop. I'm very happy with this engine modified with the Saito carb thus far. For the few that have this engine, If I knew how to post a video of the runs I would show how well the modified engine performs. Let me know if your savvy with posting iPhone videos to this site.

hello I have installed the saito 90R3 to my 7-35 and it is driving me nuts to tune it. I can get good transiion but no matter how many turns I put on the HS needle it will drop RPM at full thorttle. I can get only 6400rpm from a menz 18x6. Maybe the LS needle is too lean? Can someone using this engine and carb tell me the HS and LS needle settings for a reference?

Fulcrum, 1. as you said, idle needle in too far. Unscrew it! 2. poor seal between carb and housing. 3. fuel issue, clog in line, fuel line too long or small, too small hole in clunk (happened to me), tank too low. 4. rare but bad carb. Do you have good hearing? If so attach a fuel line to the carb and blow through the tube. Listen for air passage noise as you open the throttle. Does it increase air flow as you open it. Now, at full throttle, does the airflow increase as you open the IDLE needle?? If so as you said the idle is screwed in too far! Hope this all helps. -Tom

I have done this:
1 Removed the OS F plugs and returned to the ones that came with the engine
2. Adjusted valves. I adjusted them some months ago I didnt thought it had to be done again. I noted one of the pushrod ends was damaged, fortunately had spares and changed it. Some valves gap was off and had to change a M3 nut that holds the set screws on the valves that had the threads damaged too. It was on the same valve as the damaged pushrod so maybe it rocked too hard due to the nut being loose, who knows.

Doing that it now is a new engine, the transition is crispand the top rpm with a menz 18x6 is 7500 rpm, great.

Great, now..... slow that poor thing down with a bigger prop!!

yeah I am using a PT carbon 18x8 @6900 rpm

evo 7-77
wait until you have to replace rings in one of these! horizon doesn't sell the parts. india sells the ring as part of a "cylinder assembly" (piston, ring, cylinder, stuff that attaches cylinder to case) for much more than the price of a ring would cost, but the tool to remove the head from the cylinder will cost you $750 (india) as quoted me from ums. ums DID say that they'd consider a special case for rings only, but I haven't got back with them on that yet (took 3 times- waiting couple days 2 times, to get an answer from horizon hobby). so heare's the dilemma: see if and how much$ rings from india will be; get cylinder assy from india just in case its necessary - BUT I don't have the tool to install it on the head! ... I don't think HH will do just that part, and its ridiculous to think of getting charged for that.
.
I have heard of the rings, and maybe a cylinder, being replaced by owners a couple times previously on these engines. can any of you that have done it tell me how (tool?) and where you got the rings/cylinder from?
.
thx, andy

I replaced the rings on mine (you can even add dual rings) using the OEM UMS rings. I was able to order new o-rings and cylinder rings for my engine directly from UMS. Wasn't terribly expensive either. This was over a year ago now, so possibly Horizon has gotten wise to this and told UMS to stop it; or UMS has become wise to Horizon not wanting to sell parts and jacked their pricing up. Either or. I contacted Horizon at one point and *****ed about not being able to purchase spares for what effectively is an enthusiasts engine - and when I spend money on something like this, totally for hobby fun, then a company shouldn't be attempting to block me from playing with the engine after I purchase it; especially if I assume the risks of voiding any warranty by contacting them to tell them I don't care about the warranty!

Push a little bit and you should be able to obtain the parts. I have a whole spare engine I have myself for parts as I planned to keep this thing running for a long time. Not sure how to get the head off, but I'd imagine some heat and a pair of solid grips will help separate the two halves if needed.