dhal22

Can anyone but cees educate me on an OS 7D carb? It seems unusual. Thanks.

R_G

My Feedback: (1)

Here's a link to the [link=http://manuals.hobbico.com/osm/29081000-manual.pdf]instruction manual[/link].

RG

Atlanta 60

My Feedback: (18)

Great!! Thanks for the link to the manual...

It's suppose to be a good carb...I think it came stock on the OS 1.08 FSR engine...Apparently some of the SPA guys are running them on their OS 61 SF engines (non-pumped) for better performance...I got one for my std SF engine but haven't run it yet...

Have Fun...

Chuck

R_G

My Feedback: (1)

Here is a list of other [link=http://www.osengines.com/manuals/]O.S. manuals[/link].

RG

rcacro

Its a great carb! One of the best that OS made in that size.

John W

kiwijet

I have several .61 VF's with the 7D and from memory the .61 FSR had them as well, an excellent carb for sure!

Cheers.....Rene

dhal22

thx guys.

JeffH

My Feedback: (43)

Best carb ever made IMO. I have one on an OS 1.08(best engine OS Made) and the ONLY time I ever had to adjust the idle mixture was when my ring would wear out. I set it when new, and one day the idle started screwing up and I fiddled with it a bit and got it flyable. I noticed that the compression was a bit low and when I tore it down, the ring was shot. I could actually slip the piston back in the sleeve with any part of the ring on the anti-rotation pin. New ring, the idle mixture went right back to where it was.
I am on the third ring, and 4th set of bearing in that motor. The sleeve is still nearly perfect.

cllaurit

I used to put the 7D carb on ST. 3250's. More power, smoother transitions and much better idle.

dhal22

i was about to leave it on a ASP 1.08 that i am going to put on the big auction site. i don't even know where i got the engine. it came with 2 carbs so i will keep the 7D and sell the engine with the original ASP carb.

flywilly

My Feedback: (121)

That was the only way I could get my ASP to run reliably - sold it with the original carb, too!!

dhal22

hmmmm.... did i buy the 1.08 from you?

Taurus Flyer

Gents,

I do never buy (not new, so) second hand "important" parts for my airplanes.
You never know the history.
I do change combinations as well, see the picture.
Because of the evaporation problem and a more linear characteristic of the power output, my OS 61 FX
The carb has a enlarged bore and a modified shape of the ventury.

Cees

dhal22

wow cees!! that's outstanding. good to know.[8D]

Taurus Flyer

Yes, David,

Education is more than reading an instruction manual.

Cees

dhal22

that's why your post was totally irrelevant (as usual). i was asking about a 7D carb, not whether it should be new or used.

Chris Moon

My Feedback: (8)

The 7D carb came on the .61 FSR motors and the .61VF (rear exhaust). It had a removable sleeve inside the throttle barrel on the .61 that was removed when it was used on the larger .91 or 1.08 motors. The 7D was an excellent carb.

Oh, and it had nothing to do with an old beat up Taurus plane

billtulsa

7D, simple carb to adjust, runs excelent.


Someone from outside the US always trying to tell us why their ideas are better.

Rendegade

Funny comment, considering the carb is a Japanese design, or did you forget that?

doxilia

My Feedback: (3)

Bill,

remember, this is RC Universe. And good ideas are also often universal. Unfortunately, this may not have been the case in this instance.

Furthermore, most good engines as far as I know are either Asian or European - a few exceptional engines are American but others are mediocre.

David.

Roguedog

This is what I know about the 7D Carb.

OS Max had two different manuals for the 7D. The one listed above, for the 7D only, and the 7D-7DV manual. It's in this latter version where you will find more details for the inserts used in this carb, see the attachment.

Next there were actually four different versions of this carb.

The 7DV and three different setups of the 7D carb. The main difference between the 7DV and the 7D was in the carb rotor. The 7DV's rotor had a bore of 8.5mm, while the 7D's rotor bore was 10.5mm without the inserts.

The carb rotor inserts is where the 7D and the 7M shine. When used with a 61FSR or 61VF in the stock configuration the e.g. no pump, the carb required the 8.5mm insert to operate correctly.

For high performance output on the 61FSR and 61VF you could use the 7D with the 9.5mm insert or with no insert (10.5mm bore). The larger openings required the use of a pump for the engine to work correctly. Otherwise the 61FSR or 61VF would have problems drawing fuel at the lower RPMS.

OS Max used the 7D as the stock carb on the 90FSR and the 108FSR as well.

In the case of the 90FSR the I believe the stock configuration was with the 9.5mm insert without pump and of course the utilization of a pump without the rotor insert (10.5mm).

I'm guessing that in the 108FSR the engine would function with (9.5mm) or without (10.5mm) the insert.

One thing I have yet to here is the difference in the perfromance of the 61's using the different configuations.

As a comparison I got out a YS-60FR and Os 61RF-P and measured the throttle bores of each. The YS-60FR had a huge 11.5mm bore and the 61RF-p had a whopping 12mm bore. Of course both these engines had a pump system included.

I suspect that the carb inserts could have left some with a dim view of the 61FSR and 61VF in that using a pump with the 8.5mm insert probably didn't provide the performance boost that they where looking for. Still the YS-60's had a huge throttle bore as compared to OS 61's at that time is probably the main reason for the difference in performance.

Anyone have any performance specs on the different configurations of the 7D?

Bryan.

Rendegade

Wonderful! Very comprehensive!

Taurus Flyer

David, gents

I know exactly how to optimize a carburetor system for that I did show the picture.

For me it does not matter the brands, only important are, reliability, characteristic, fuel consumption, fuel air ratio, throttle ability etc.
Why my post 13,

I only did read halleluiah stories see the posts x - 11, but probably all about a (new?) undisturbed carburetor.
That was why I did warn for second hand stuff without knowing where it is coming from, as dhal22 did write (and has a lot of?).

IMPORTANT

The educating came later, after I did post, see ual767, post :

The 7D carb came on the .61 FSR motors and the .61VF (rear exhaust). It had a removable sleeve inside the throttle barrel on the .61 that was removed when it was used on the larger .91 or 1.08 motors. The 7D was an excellent carb.


All (modern) carburetors are designed to combine with muffler pressure.
When you remove the carburetor insert, the sucking pressure will be less so throttle ability and fuel consumption maybe not as optimal as you wish. Finding back the insert after you is told this, is normally impossible.
I only enlarge a bore when I use a fuel pressure regulator, see the picture, maybe is a better advice.
ual767 also writes:

Oh, and it had nothing to do with an old beat up Taurus plane

Yes it has, Ed Kazmirski was one the pilots of who we can read he did modify the carburetor barrels (VECO45RC, Super Tigre).
I can tell you, the shape of a vertury has a lot to do with the recovery of the sucking pressure too so there is much more to tell!.

old beat up Taurus plane

The Taurus on the picture does have real time air speed control and data logging capability, show me yours!

Cees


Didn't see the two posts before this one because I was writing my post, so there are much more details important!!!!!

Taurus Flyer

Do you see, ual767


Roquedog/Brian
In the case of the 90FSR the I believe the stock configuration was with the 9.5mm insert without pump and of course the utilization of a pump without the rotor insert (10.5mm).

I'm guessing that in the 108FSR the engine would function with (9.5mm) or without (10.5mm) the insert.

90FSR has an insert believing and 108 FSR is still guessing.


For me only facts are important to know and for that I always search for own data and give my (brand-less) second opinion.


Cees

Rendegade

Oh brother, here we go again. [:@]

Does RCU have an ignore function?