O S Max Venturi Dimensions

LAST EDITED ON Nov-25-04 AT 06:55 PM (CST)
 
Well it was a rainy day today so I took on a project. There are always questions regarding OS Max venturi (what the H... is the plural form). I dug into my parts bin and measured some for reference and thought I'd share. (Mom would be proud!) All of these are parts purchased within the last year... so they are current production.

It's a bit more difficult without a drawing but I think you can get the idea. The values are separated by a dash and they correspond to the names in sequence in the first row.

For clarification

O.S. Max Pt. No. - The part no. OS uses on the package

Description - Their description on the package

OD Top Of Venturi - Hold the venturi upright with the part that inserts into the case down and this is the outer diameter of the top of the venturi . The bigger part.

OD Bottom Of Venturi – Same explanation as above but the smaller bottom portion

Overall Lg. -

Min. I.D. - The smallest portion of the bore...the hole.

Case Insert Length - The length of the small part that fits into the case. Measured from the shoulder to the end nearest crank.

Needle CL to shoulder - Location of the spray bar hole from the shoulder to the center of the hole.

Needle Bore Dia - The diameter of the hole described above

Flange Dia. - That little shoulder that flairs out at the bottom of the top portion of the venture. It sets on the case.

Hope this answers a few questions. I also have this is an Excel spreadsheet. If you want it send me and e-mail and I’ll send it.

[email protected]

Edited Part - Addition of the Needle valve spraybar information

_______________________________________________________________________________

O.S. Max Pt. No. - Description - OD Top Of Venturi - OD Bottom Of Venturi - Overall Lg. - Min. I.D. - Case Insert Length - Needle CL to shoulder - Needle Bore Dia - Flange Dia.

25412100 - 40SF-S,46SF-S - 0.550 - 0.530 - 0.944 - 0.305 - 0.317 - .167 - 0.145 - 0.660

25412000 - 40, 46SF-S - 0.550 - 0.530 - 0.944 - 0.288 - 0.317 - 0.167 - 0.145 - 0.660

23312000 - 40FP-S - 0.504 - 0.391 - 0.866 - 0.283 - 0.355 - 0.190 - 0.145 - 0.543

23312100 - 35, 40FP-S - 0.488 - 0.391 - 0.871 - 0.266 - 0.355 - 0.190 - 0.145 - 0.543

22312000 - 20, 25FP-S - 0.472 - 0.391 - 0.787 - 0.258 - 0.355 - 0.190 - 0.145 - 0.543

21712010 - 15FP-S - 0.464 - 0.333 - 0.669 - 0.235 - 0.323 - 0.165 - 0.145 - 0.496

21112003 - 10FP-S - 0.411 - 0.333 - 0.628 - 0.235 - 0.323 - 0.165 - 0.163 - 0.452

22311000 - O.S. Max Needle Valve Assy. 20-40 FP-S - 0.136 Spraybar O.D.

21711000 - O.S. Max Needle Valve Assy. 15 FP-S - 0.125 Spraybar O.D.

Super Tiger Needle Valve Assy G51 CL - 0.155 Spraybar O.D.

Fox .35 - .125 Spraybar O.D.

Excellent Job!!

I would like to have a copy of the file.
[email protected]

SO...what is this for????? Not getting it. I make venturi's and..... I’m puzzled. Please help me out.

PS .....That’s ok with your engine. I've found out that there could be .004 differences in engines. The holes through the case sometime are not square to the crank.I.e.. Veco 61 each of the one's I've done are .004 off. SO the nva is at an angle.

Most of the OS engines are within .003

Hmmmm let me think..... OK how about.

If I have an LA Series 40 or 46 engine I have three venturi that will fit it. 23312000 23312100 22312000 all giving a different choke area.

Or if I want to put a ST NV assy I'm going to have to drill the venturi spray bar hole. (.155" dia.)

OR does OS make a CL venturi for ny 15FP RC engine.

or I have this old brand x motor, I wonder if an OS venturi would fit it.

Or........

Dick (it seemed like a good idea at the time) Fowler

I also roll my own, so my viewpoint tends to agree with Scott's (for a change). Was I to have a handy stockpile of OS venturis, NIP, it would be handy, but I don't, so it isn't. If it would be handy for you, just copy and paste Dick's post into WordPad or such.

Leonard complains about OS Venturis varying a lot, but I'd remind all that there are tolerances on every dimension of every part drawing ever made. Sometimes it isn't much, sometimes not enough, but I'd expect the venturi bore would probably be at least .1mm (.004"), if not .2mm or .3mm (.012" for the math challenged). That's what tolerances are for. If everything had to be nominal, we couldn't afford to buy anything. No point to that, right? Steve

LAST EDITED ON Nov-24-04 AT 08:58 PM (CST)
 
Steve... I also turn my own but I bought some from the factory to see if there was anything unique about any of them. Not really, kind of run of the mill. Not everyone has this capability and must purchase them.

I have measured probably six to eight of the smaller 40 size factory venturi over the last two years and the I.D. dimensions haven't varied more than .001" (actually more like .0005" total spread). They seem to be doing a reasonable job on this item.

Dick.....thanks for the info....

>I also roll my own, so my viewpoint tends to agree with
>Scott's (for a change). Was I to have a handy stockpile
>of OS venturis, NIP, it would be handy, but I don't, so it
>isn't. If it would be handy for you, just copy and paste
>Dick's post into WordPad or such.
>
>Leonard complains about OS Venturis varying a lot, but I'd
>remind all that there are tolerances on every
>dimension of every part drawing ever made. Sometimes it
>isn't much, sometimes not enough, but I'd expect the venturi
>bore would probably be at least .1mm (.004"), if not .2mm or
>.3mm (.012" for the math challenged). That's what tolerances
>are for. If everything had to be nominal, we couldn't afford
>to buy anything. No point to that, right? Steve
>
>http://www.nwskyraiders.com/index.html

If you have a lathe and make your own venturi it's a great reference.
Regards,
John Jolley

I have several O.S. .40s (LAs & FPs)
Which of the venturis digs the deepest DIVOT!!

By the by, I have those TT .25 venturis you wanted.. next time we get together I'll have them..... Hey,,,, you got anymore plastic back plate replacements?

"Long story short"

Rog

Dick

Thanks for the info, it is useful. However, there is some truly bizarre thinking in the sizing of some OS stunt parts.

For example:

The FP 20/25 and 35/40 and LA 40/46 all use the same NVA with 3.5mm dia spray bar and the FP 10 has a 4mm spraybar knecked down to 3.5mm across the venturi throat—go figure that!

However, my new FP 15 NVA has 0.125" dia spray bar. Are you sure of the hole size for teh 15 venturi? It seems to be a rattling good fit that could cause grief if not properly sealed.

Thanks again