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BVM.91 Connecting rod

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BVM.91 Connecting rod

Old 02-23-2015, 03:02 PM
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tflame
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Default BVM.91 Connecting rod

I have been offered a BVM.91 with fan unit and pipe but on taking a look at the engine insides I can tell it will need a new rod. Does any body has a new rod for sale?
J.V.
Old 02-24-2015, 04:33 PM
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roger.alli
 
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The quickest way to get an answer to your question would likly be to contact BVM direct and ask them if any manufacturer is still supporting these engines.. I seem to recall that Jett Engineering Inc. (google them) was suppling parts for them a while ago, but I’m not sure of this fact..

You may already know this. The BVM DF engine, like all high performance piston engines, had large big end clearances to allow for the high RPM. New engines also had very tight piston to liner clearances at the top, which coupled with the “loose” big end, would result in a pronounced “CLICK” when turned over by hand. This could be confused as a worn big end of the rod..

Having said this, if you have any doubt at all, it would be worth changing the rod. They fail spectacularly!.

I have owned 2 of them. Brilliant engines. A piece of history now though..
Old 02-24-2015, 06:14 PM
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Hello Roger
Yes I hear a click and with the backplate removed I can see the crankpin move on the conrod bushing. I don`t know how much clearance is supposed to have also I have no paperwork or operating instructions. I couldn`t find info on the internet via google. Do you by any chance have the operating instructions? Thanks for the reply mate.
J.V.
Old 02-24-2015, 07:20 PM
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roger.alli
 
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HI JV,

These engines were discontinued way before the internet. Well almost.. I will have a look at home and see if I can find the manuals.. Give me a day or so. I am pretty sure i have retained them..

Roger
Old 02-25-2015, 03:13 AM
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Harley Condra
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Try Dave Shadel at Performance Specialties in Gardner, Nev.
As I recall hearing, he was the only guy on this planet that has any parts for those engines.
Here's his contact info:

Performance Specialties
P.O. Box 3146
Gardnerville, NV 89410
Office Phone: 775-265-7523
E-mail: [email protected]

Say Hello! to Dave for me. We are old friends.
Old 02-25-2015, 03:58 AM
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darryltarr
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Hi JV, as Harley mentioned Dave Shadel is the guy to contact. His service is outstanding however, I recently bought some BVM .91 spares from him and do know that stocks are very limited, almost non-existent. Very sad.

I'm still looking for a Piston for my BVM .96 Ducted Fan Engine but that's like searching for hen's teeth.

Darryl Tarr
BVM Field Rep

Last edited by darryltarr; 02-25-2015 at 04:04 AM.
Old 02-25-2015, 06:10 AM
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zonker123
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Pull the rod and look at the big end bushing. Make sure the bushing has not spun in the rod covering up the lubrication holes drilled into the big end journal. This is the usual culprit leading to rod failure in these type engines. Did it a gazillon times running Nitro boats years ago. At least until some of the motors started showing up with Needle bearing big ends. Then we started shearing crank pins, And the beat went on........

take care
Mike
Old 02-25-2015, 07:24 AM
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JeffH
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If I recall correctly, .003" is the magic number for the clearance on the big end.Check with a local machine shop if the bushing is indeed worn out. It is a simple task for them to remove then press and clearance a new bronze bushing. Make sure they chamfer the edges and open up the oil holes.
Old 02-25-2015, 07:52 AM
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Also, when you've got it apart, make sure that oil port is installed facing the carb. It's easy to not pay attention and point it the wrong way. I've got a broken one on the wall in the shop. Remember the day it seized up mid flight. was the most abrupt stopping of sound.....

Thanks,
Lance
Old 02-25-2015, 09:53 AM
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Art ARRO
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J.V.,
You may want to contact Mike Langlois at https://aeroracingengines.com. Mike services Nelson racing engines and may be able to rebush or remake your connecting rod. Also, try Clarence Lee and his contact can be found in the Classified Ads section of "Model Aviation" magazine. Note that Clarence can be best reached by snail mail. Finally, there was a John Ackerman that was producing conrods for the early OS DF engines, ie. OS 65 VRDF and OS 77 VRDF. I recall that he resided in the Indianapolis, IN area but have lost tract of any contact info. Good luck in your quest.
Rgds,
Art ARRO
Old 02-25-2015, 03:20 PM
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Hello Guys
I really appreciate all the help, I bought the engine after taking a good look. I have the engine,fan and tuned pipe that goes with it. I took it apart to give it a good cleaning,replace the bearings and I will be drilling the rod for an extra oil hole in the big end. The cilinder and piston have normal wear but it seem like the engine was not used much. the conrod play is as Roger stated I was able to hear it click. I will be measuring the conrod bushing and crank pin to make sure it doesn`t have excessive wear. I have been around model engines for a long time and I took it apart very carefully to avoid damage to any parts. I grateful for all the information you guys have provided. I have dealt with Dave Shadel previously and tried his site on the internet but is there no more. I will be giving him a call. I had bought Nelson Q 500 .40 engines from him and I know that the quality of The Nelson engines are second to none. Still have a few.Thanks.
Juan

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Old 02-25-2015, 04:01 PM
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mr_matt
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Hello,

If anything, the clicking means you have good clearance. I went through a lot of pistons and sleeves (normal wear) but never a rod on BVM 82, 91R or the 96.

I would guess the clearance should be about 0.003 in, Col Thacker showed me an old trick, that is about the thickness of a page of a magazine.

I would not drill anything or modify anything but of course that is your choice. And start looking for spare pistons and sleeves!
Old 02-25-2015, 04:59 PM
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Tom R. Maddox
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just a little info for ya !! talked to dave shadel last fall about my os 91 and the availability of a shadel piston and liner? they are all gone and that goes for the BVM stuff also!! also spoke to JOHN ACKERMAN also as i used to have john build me and my buddys OS 91s. JOHN sold all his tooling to a guy from tampa MARTY who is a r/c boat guy as was john ackerman. Martys phone # is 727-867-9696. him and a guy named Norm Doeer were going to start building some boat engines.but they could also do ducted fan engines!! there is also the guy in the north east i think OHIO that is still doing the nelson Q40 pylon engines. as Henry Nelson as in nelson bvm engines is also out of the game. fyi look at your nelson BVM engine at the top of the outside left side of the engine case there is a small dot (drill mark) witch is known as a one dot engine (sport timeing) if there were 2 dots there that would be the R engine. (race) with higher port timeing for more RPMs. my STARFIRE i am building is getting a pumped up OS91. i am not interested in EDF flying for 4 minutes. and 3 to 4 pounds heavier. plus you can smoke a edf and fly for 7 min. clocked 218mph with my old starfire (no gear doors) going to clean this one up. also moving all linkages inboard. looking for 230 MPH. the old BVM ultra viper clocked 255MPH at a texas rally back in the day!!!! put that in your EDF pipe and and smoke it. THANKS AND ENJOY TOM the flyin wambat

Last edited by Tom R. Maddox; 02-25-2015 at 05:11 PM.
Old 02-25-2015, 05:14 PM
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Hi Juan,

Send me your email address via Private Message.. I have found the manuals!!

Roger
Old 02-25-2015, 06:26 PM
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Hi Tom

What kind of pump are you using in the OS?

Javier
Old 02-25-2015, 06:57 PM
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Hello Guys
The engine I have is the Sport version according to what Tom R wrote,it has a single dot on the left top fin to the rear. I`m glad is not the R version it should be easier to deal with. I took the bearings out and the front one has a part number ,the rear one I can`t find a number in it. Are the bearings sold by Boca Bearings good for this engines? I`m taking about the high speed ones not the economy. They have corrosion and need to be replaced. I will make sure everything is ultra clean before assembly. I took the crank and barings out. Thanks guys the more info I get the better.

Juan
Old 02-26-2015, 11:45 AM
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Hello Roger
Downloaded the manuals Thanks I really appreciate it,now I will make sure I read them 3 or 4 times to make sure I don`t make any mistakes with the engine. After reading them for the first time I found out my engine is a BVM.91R.Thanks again.
Juan
Old 02-26-2015, 01:35 PM
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Tom R. Maddox
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hello JAVIER. there is NO PUMP. it is just an expression as in hopped up. pumped up. modified etc. the os 91s have a rolled lip carb modification. piston and liner are corked . we used to have john ackerman do that. maybe marty can still do it. JMP (tom cook) MK 2 high volume pipe. rpm rod. shadel piston and liner.
Old 02-26-2015, 01:41 PM
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Tom R. Maddox
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hello JAVIER. there is NO PUMP. it is just an expression as in hopped up. pumped up. modified etc. the os 91s have a rolled lip carb modification. piston and liner are corked . we used to have john ackerman do that. maybe marty can still do it. JMP (tom cook) MK 2 high volume pipe. rpm rod. shadel piston and liner.
Old 02-26-2015, 01:47 PM
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Tom R. Maddox
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Default Bvm 91

Hello JUAN !! i guess i was wrong! it was my understanding that a 1 dot engine was a sport engine. and the the 2 dot engine was the r or race version. what does it say in the manual that indicates that your engine with 1 dot is a R engine?? does the sport engine have no dots. and the r has 1 dot. just would like to KNOW !! THANKS TOM. could you forward the manual to me . as a friend of mine has just bought 3 BVM 91s and a BVM 96. THANKS AGAIN TOM at [email protected]

Last edited by Tom R. Maddox; 02-26-2015 at 01:51 PM.
Old 02-26-2015, 03:24 PM
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roger.alli
 
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Originally Posted by tflame View Post
Hello Roger
Downloaded the manuals Thanks I really appreciate it,now I will make sure I read them 3 or 4 times to make sure I don`t make any mistakes with the engine. After reading them for the first time I found out my engine is a BVM.91R.Thanks again.
Juan
No worries Juan.

I think the R version was a lot more popular.. They are not difficult to operate, if you stick to the book.

Roger
Old 01-01-2019, 05:45 PM
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Default Bvm .91/.96 manual

Hey me roger I have a bvm .91 used engine itís in really good shape I know I will probably never find rebuild parts but Iím gonna run her until she quits .I was reading an old post that you helped a guy out with a copy of manual for the engine I sure would appreciate a copy if it would not be to much trouble thank you. Email [email protected]

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