Author Topic: OS Max 46 VF ring - venturi bore. (Read 3254 times)

Chris Wilson · « **on:** March 13, 2013, 03:12:30 PM »

Hi all,
just inherited an old RC OS Max 46 VF ringed engine from a friend and I am going to use an Enya 60 4mm through spraybar and ask a mate to turn me up an alloy venturi insert.
Question, "What would be a good bore size to start with?"

(Full length stunt pipe intended for use.)

This old engine seems to be brilliant compression but gravelly bearings and there is surface rust visible in the crank passage when looking down the intake.
Methinks that this would translate into the bearings also.

Anyway, first things first - venturi size?

Thanks.

Brett Buck · « **Reply #1 on:** March 13, 2013, 05:51:49 PM »

Quote from: Chris Wilson on March 13, 2013, 03:12:30 PM

Hi all,
just inherited an old RC OS Max 46 VF ringed engine from a friend and I am going to use an Enya 60 4mm through spraybar and ask a mate to turn me up an alloy venturi insert.
Question, "What would be a good bore size to start with?"

(Full length stunt pipe intended for use.)

This old engine seems to be brilliant compression but gravelly bearings and there is surface rust visible in the crank passage when looking down the intake.
Methinks that this would translate into the bearings also.

Anyway, first things first - venturi size?

Thanks.

I would suggest the equivalent of a .265 venturi with an ST spraybar (which may be 4mm, too). Make a .260, .270, and a .275 as well.

Brett

Chris Wilson · « **Reply #2 on:** March 13, 2013, 06:10:45 PM »

Quote from: Brett Buck on March 13, 2013, 05:51:49 PM

I would suggest the equivalent of a .265 venturi with an ST spraybar (which may be 4mm, too). Make a .260, .270, and a .275 as well.

Brett

Thanks Brett, 0.265" or 6.731mm sounds good to me.

Cheers.

Brian Hampton · « **Reply #3 on:** March 13, 2013, 08:41:09 PM »

G'day Chris
I was using a 40VF with a 4mm spray bar and .282" (7.15mm) venturi which worked perfectly. Then I managed to score a brand new (RC) 46VF so, based on the larger swept volume, I did some calculations and bored out the 40's venturi to .294" (7.45mm) to get the exact same ratio of effective venturi area to swept volume (.048). Never knew there was a ringed VF though unless maybe it was a heli version.

RandySmith · « **Reply #4 on:** March 13, 2013, 09:05:45 PM »

Quote from: Chris Wilson on March 13, 2013, 03:12:30 PM

Hi all,
just inherited an old RC OS Max 46 VF ringed engine from a friend and I am going to use an Enya 60 4mm through spraybar and ask a mate to turn me up an alloy venturi insert.
Question, "What would be a good bore size to start with?"

(Full length stunt pipe intended for use.)

This old engine seems to be brilliant compression but gravelly bearings and there is surface rust visible in the crank passage when looking down the intake.
Methinks that this would translate into the bearings also.

Anyway, first things first - venturi size?

Thanks.

Hi Chris

You maybe want to check it, I have never seen a ringed VF 46, as for the venturie sizes you can use a .275 in. and have one smaller one larger 265 and .285. We used a 12 x 4.5 3 blade or a 12.25 x 4.25 2 blade, with a 18 inch pipe lenght for 2 blade and 18.5 for the 3 blade.
Try not to run the motor with any rust in it as it will kill other parts as the oxide runs thru it

Randy

Chris Wilson · « **Reply #5 on:** March 13, 2013, 09:35:17 PM »

Hi guys,
99.9% sure that there is a ring in there!

Very distinct dark band around the very top of the piston, I can definitely feel a groove between the ring and the piston wall when using a soft toothpick as a probe and the top of the piston when viewed through the exhaust port shows me a circumferential band around the top of the piston crown.
Looking like a dykes ring.

But the other 0.01% of doubt I harbor will be erased when I pull the head off this weekend with long time stunt flier and machinist Herb Hanna.

Rust, yep its going to need a strip down to check the bearings and a general clean out.

And a pipe to suit.

But at the moment the compression is phenomenal, even my PAW 40's are impressed being parked next to it!

Cheers.

Balsa Butcher · « **Reply #6 on:** March 13, 2013, 11:19:31 PM »

I think you will find that you are looking at an oil groove in the top of the piston. Many ABC engines have one and they look like rings unless you look real close. Good luck with that engine, it sounds kind of marginal corrosion wise despite the good compression. I hope are able to restore it as they are good engines.

Chris Wilson · « **Reply #7 on:** March 14, 2013, 05:44:23 PM »

Quote from: Balsa Butcher on March 13, 2013, 11:19:31 PM

I think you will find that you are looking at an oil groove in the top of the piston. Many ABC engines have one and they look like rings unless you look real close. Good luck with that engine, it sounds kind of marginal corrosion wise despite the good compression. I hope are able to restore it as they are good engines.

Could well be an oil groove actually, I looked harder and more suspiciously today and I think that the circle on top of the piston was simply a meniscus formed by oil and the groove I am picking up on is just that - a groove. (I am learning I suppose.)

Everything can be restored but is it worth it in the end? $100 for the pipe, bearings could be shot, going to have to donate a spraybar, needle valve and venturi - and that's the problems that I know about!

Anyway, I will pull it down this weekend and decide its fate then.

Brett Buck · « **Reply #8 on:** March 14, 2013, 05:57:29 PM »

Quote from: Chris Wilson on March 14, 2013, 05:44:23 PM

Could well be an oil groove actually, I looked harder and more suspiciously today and I think that the circle on top of the piston was simply a meniscus formed by oil and the groove I am picking up on is just that - a groove. (I am learning I suppose.)

Everything can be restored but is it worth it in the end? $100 for the pipe, bearings could be shot, going to have to donate a spraybar, needle valve and venturi - and that's the problems that I know about!

Anyway, I will pull it down this weekend and decide its fate then.

I think a bearing set is $25:

http://www.bocabearings.com/search.aspx?SearchType=StartModel&ProductGroupID=2&MFGSYSID=0&ModelName=&Feature=

It's a very superior stunt engine, one of the best.

Brett

Chris Wilson · « **Reply #9 on:** March 14, 2013, 06:35:56 PM »

Quote from: Brett Buck on March 14, 2013, 05:57:29 PM

I think a bearing set is $25:

http://www.bocabearings.com/search.aspx?SearchType=StartModel&ProductGroupID=2&MFGSYSID=0&ModelName=&Feature=

It's a very superior stunt engine, one of the best.

Brett

Thanks for the link Brett.

Brett Buck · « **Reply #10 on:** March 14, 2013, 07:12:04 PM »

Quote from: Chris Wilson on March 14, 2013, 06:35:56 PM

Thanks for the link Brett.

Try this one, it's more to the point

http://www.bocabearings.com/bearing-inventory/2151/rc-engine-bearings/econo-power/os-engines-vf-abc-rc-46

Brett

Chris Wilson · « **Reply #11 on:** March 14, 2013, 07:34:59 PM »

Quote from: Brett Buck on March 14, 2013, 07:12:04 PM

Try this one, it's more to the point

http://www.bocabearings.com/bearing-inventory/2151/rc-engine-bearings/econo-power/os-engines-vf-abc-rc-46

Brett

Coincidentally enough, that is the page I just bookmarked.

You think that anyone wants to hear back about this once I am done?

Martin Quartim · « **Reply #12 on:** March 14, 2013, 09:52:44 PM »

I have been testing Enya 45CXL with a 60 size pipe and seems to be working quite well. So perhaps if you get a .60 size pipe the money will not be wasted if you could use it with a future 60 size engine later.

And by the way the header for the 46VF has the same mounting holes of the Enya 61CXLR

But do ask the pipe expert about using a bigger pipe. I just start using pipes last year and still learning about them.

Also, the Enya 45 with the 60 size pipe sounds much better then I have seen 46VF with a regular 45 pipes.

Just a thought

Martin

Howard Rush · « **Reply #13 on:** March 14, 2013, 11:14:39 PM »

I tried what was then a .60-size pipe on an OS .40VF several years ago. It felt like it had a little quicker speed recovery in the corners, as I remember. I would have chosen the larger pipe if I didn't have previous experience with the smaller one, but I was familiar with the smaller one, so I elected to keep it.

ash · « **Reply #14 on:** March 14, 2013, 11:24:53 PM »

Quote from: Chris Wilson on March 14, 2013, 05:44:23 PM

Anyway, I will pull it down this weekend and decide its fate then.

Add "sell it to Ash" to your list of possible fates

Chris Wilson · « **Reply #15 on:** March 14, 2013, 11:32:11 PM »

Quote from: ash on March 14, 2013, 11:24:53 PM

Add "sell it to Ash" to your list of possible fates

Hah! The guy who gave it to me would simply kill me if I did that!

(Waddya willing to give for it?)

RandySmith · « **Reply #16 on:** March 15, 2013, 10:02:45 AM »

The larger standard 60 pipe works well on the VF 46, but you need to use the smaller venturie, ie if you using a 285 then go to the 275 or if using a 275 go to the 265, you do not need to go smaller than that

Also I have many parts for them, gaskets, bearings, case cranks, venturies, NVAs , pipe, headers, props etc let me know if you need anything

Randy

Chris Wilson · « **Reply #17 on:** March 17, 2013, 03:21:54 PM »

Quote from: RandySmith on March 15, 2013, 10:02:45 AM

The larger standard 60 pipe works well on the VF 46, but you need to use the smaller venturie, ie if you using a 285 then go to the 275 or if using a 275 go to the 265, you do not need to go smaller than that

Also I have many parts for them, gaskets, bearings, case cranks, venturies, NVAs , pipe, headers, props etc let me know if you need anything

Randy

My friendly machinist made me a 0.265" venturi on the weekend so the 60 size pipe is the go now?

I popped the bearings out last night and the front one is so new that it still had its packing grease in it, but it has an incurable 'notchiness' to it.
The rear bearing was discolored (probably rust) but ran fractionally better than the front - so I don't trust either of them, they have to be replaced.

Slight surface rust on the crankshaft but not on the running surfaces and I so taped up the big end and center journal of the shaft and used wet and dry abrasive paper and kero to remove what I could. What was surprising is the amount of galling on non critical crankshaft surfaces and getting all the oxide out of these grooves proved impossible.

Compression - still phenomenal!

Randy, I will PM you concerning bearings, gaskets and 60 size pipe.
Thanks.

Brett Buck · « **Reply #18 on:** March 17, 2013, 04:09:04 PM »

Quote from: Chris Wilson on March 17, 2013, 03:21:54 PM

My friendly machinist made me a 0.265" venturi on the weekend so the 60 size pipe is the go now?

I popped the bearings out last night and the front one is so new that it still had its packing grease in it, but it has an incurable 'notchiness' to it.
The rear bearing was discolored (probably rust) but ran fractionally better than the front - so I don't trust either of them, they have to be replaced.

The "notches" are probably hardened grease residue, but sometimes that's just about impossible to remove.

I would also get a .260 venturi. Depending on the prop, and the desired run RPM, it's pretty easy to get far too much boost in the corners. Unlike a lot of the other engines, the 46VF will run across the break without undue drama if you set it up correctly (much like the RO-Jett 61 "Brett" version), but for starters its a lot easier to get it to run right in a constant 2-stroke. To do that you might need a smaller venturi.

Brett

Chris Wilson · « **Reply #19 on:** March 17, 2013, 04:13:24 PM »

A 0.260?

Wow, that is visually small and the 4mm spray bar dominates the view even with the 0.265 in place.

Thanks Brett.

Steve Helmick · « **Reply #20 on:** March 19, 2013, 11:15:28 PM »

I'm surprised that nobody suggested choking down a "too big" venturi with layer(s) of pantyhose nylon, but then remembered that Aussie girls don't seem to wear them. Won't go into further research findings!

My .46VF runs nice with the small Randy Aero pipe it came with, but I came up with a better propeller, clipped and re-carved from a 12.25 x 3.75 APC. Nice not to have to re-pitch, IMO. I'll admit it, I'm not very good at pitching props or throwing Fox .15's. I think the venturi is .272" with the .156" spraybar through, and I've got just one layer of PH over the venturi. The bad thing about that stuff is that it stretches so much that you may not get similar results if you replace it with new. I stretched it out a bit; ok with that to keep the rocks out more than any other reason.

Steve

Chris Wilson · « **Reply #21 on:** March 24, 2013, 03:28:19 PM »

Quote from: Brett Buck on March 14, 2013, 07:12:04 PM

Try this one, it's more to the point

http://www.bocabearings.com/bearing-inventory/2151/rc-engine-bearings/econo-power/os-engines-vf-abc-rc-46

Brett

I obtained the front race locally easily enough but the back one is proving to be difficult to get here in Oz and unless some local bearing guru can think of an equivalent it's
Boca to the rescue!

Next question, the front race came complete with seals and obviously the back seal should be removed but how about the front one?
It does protect from dirt ingress but seems to increase drag and the prop driver cups back over the race housing anyway.

Thanks.

RandySmith · « **Reply #22 on:** March 24, 2013, 07:11:14 PM »

Quote from: Chris Wilson on March 24, 2013, 03:28:19 PM

I obtained the front race locally easily enough but the back one is proving to be difficult to get here in Oz and unless some local bearing guru can think of an equivalent it's
Boca to the rescue!

Next question, the front race came complete with seals and obviously the back seal should be removed but how about the front one?
It does protect from dirt ingress but seems to increase drag and the prop driver cups back over the race housing anyway.

Thanks.

Leave the front seal on, the rear is a special bearing OS has made, that is why it is hard to find, it is called an OS160 I have them here in phenolic cage hi speed versions

Randy