Proper liner/head spacing for Nelson QM40  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> QM-40 Racing >> Proper liner/head spacing for Nelson QM40
Page: [1]

Login
Message << Older Topic   Newer Topic >>
Proper liner/head spacing for Nelson QM40 - 7/5/2006 4:20:21 PM   
jprge C.


 

Posts: 46
Joined: 11/15/2002
From: Lock Haven, PA,
Status: offline 		Hello,
Thank you for the information with the spinner for the Nelson. Can someone please tell me the correct shim set up for the nelson. I measure the engine with out shims, the head measures .185 and the liner to the top of the piston is .186" The shim under the liner when I got the engine was .010" and under the head was .003" Does this sound like a proper setting. I am using the new lighter pitch CF quarter midget APC prop.

Thanks
Jorge
       Post #: 1

RE: Proper liner/head spacing for Nelson QM40 - 7/5/2006 5:31:22 PM   
garys


 

Posts: 755
Joined: 1/31/2002
From: San Diego, CA, USA
Status: offline 		That sounds good to start, each engine has its own characteristics and they don't all run with the same settings. Did you get the engine new from Dave Shadel? If so, why did you bother to take it apart? Dave's already test ran it and has it set properly so there isn't a need to take it apart.

_____________________________

GS

(in reply to jprge C.)
       Post #: 2

RE: Proper liner/head spacing for Nelson QM40 - 7/5/2006 10:54:31 PM   
Ed Smith


 

Posts: 2834
Joined: 12/29/2001
From: Brantford, ON, CANADA
Status: offline 		Gary and I will never agree on this. I recommend that a new engine should always be taken apart and washed out. Rarely have I washed out a new engine and NOT found aluminum chips in the bowl.

The measurements quoted will give 0.196 deck height and 0.014 head clearance.

The two Q40s I purchased last year had 0.196 deck height and 0.017 head clearance. Yours may be a little tight.

However, as Gary stated, not all engines run the same. You will have to fly it and try it. Make some changes, it is a learning process.

Ed S

(in reply to garys)
       Post #: 3

RE: Proper liner/head spacing for Nelson QM40 - 7/5/2006 11:20:16 PM   
daven



Posts: 6897
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		I've done it both ways, they all vary a little. I personally like to take them apart and measure myself, but I put trust in Dave on my two engines this year, and both seem to be working well, so what do I know.

I typically run .196 and .016 on Q40 motors, many are running closer to .193/4 and .013/.014.

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to Ed Smith)
       Post #: 4

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 2:48:23 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		I always thought that the tighter the head the harder it was to needle... I don't know if that's true across the board but I know it is with one of my quickie motors... It seemed to make it really finicky...


_____________________________

Lee LaValley
NMPRA# 33w

(in reply to daven)
       Post #: 5

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 3:31:55 PM   
daven



Posts: 6897
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		a tighter motor will be more finnicky to needle, but can also be faster.

Take your tradeoffs, I prefer an engine that I can consistenly get a good needle.

< Message edited by daven -- 7/6/2006 3:33:00 PM >

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to diggs_74)
       Post #: 6

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 3:41:04 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		I don't have a lot of experience with these yet so I prefer to make at easy as possible...


_____________________________

Lee LaValley
NMPRA# 33w

(in reply to daven)
       Post #: 7

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 4:47:20 PM   
Super Splatter



Posts: 395
Joined: 3/21/2006
From: , MN, USA
Status: offline
quote:

ORIGINAL: diggs_74

I don't have a lot of experience with these yet so I prefer to make at easy as possible...


aka.... I'm from Wisconsin

(in reply to diggs_74)
       Post #: 8

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 5:48:39 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		I should have seen that coming...


_____________________________

Lee LaValley
NMPRA# 33w

(in reply to Super Splatter)
       Post #: 9

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 7:17:59 PM   
daven



Posts: 6897
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		A beer in one hand, a caliper in the other, you'll figure it out in about 2 hours

Then again, who am I to judge

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to diggs_74)
       Post #: 10

RE: Proper liner/head spacing for Nelson QM40 - 7/6/2006 8:13:44 PM   
diggs_74



Posts: 1281
Joined: 1/20/2004
From: Emerald, WI, USA
Status: offline 		Everything goes better with beer


_____________________________

Lee LaValley
NMPRA# 33w

(in reply to daven)
       Post #: 11

RE: Proper liner/head spacing for Nelson QM40 - 7/7/2006 2:42:11 AM   
jprge C.


 

Posts: 46
Joined: 11/15/2002
From: Lock Haven, PA,
Status: offline 		Hello,
I bought the engine and airplane brand new at a swap meet back in late April. I have just had to work so many hours it is only now I am getting to work on it. The engine is brand new, I even have the paperwork and the credit card reciept was along with it. It was bought from Nelson Competition Engines, PA in 2004. The reason I took the engine apart is going by what Terry Prather allways said, "it can't hurt if you are careful and you might find something I missed"
I left the engine alone and ran it with an FAI prop I had that I cut down to 7". After 5 runs like that I put the CF APC prop, the 7.8x8 I believe and it turns 22,800 and will pinch to 23,700. Friday I hope to fly it and will report the results.


Jorge

(in reply to jprge C.)
       Post #: 12

RE: Proper liner/head spacing for Nelson QM40 - 7/7/2006 2:51:38 AM   
daven



Posts: 6897
Joined: 12/7/2001
From: Andover, MN, USA
Status: online 		If your getting those kind of rpms, your doing better than me

_____________________________

Dave Norman

klasskote.com
supertrc.com

(in reply to jprge C.)
       Post #: 13

RE: Proper liner/head spacing for Nelson QM40 - 7/21/2006 4:20:49 PM   
jprge C.


 

Posts: 46
Joined: 11/15/2002
From: Lock Haven, PA,
Status: offline 		Hello,
Well I now have 6 flights on the plane and engine and it really goes quite well. I was hoping to take it to Bowie, but I have found the race has been cnceled. I will have to wait until next year to get a true comparison on how well it does go. The Nelson is very easy to run and the final set up with the shims has ended up at .009 under the liner and .003 under the head. It needles well and runs perfect through the tank.

Jorge

(in reply to daven)
       Post #: 14

RE: Proper liner/head spacing for Nelson QM40 - 8/3/2006 12:46:21 AM   
SmokinJoe



Posts: 129
Joined: 8/20/2002
From: HamiltonQueensland, AUSTRALIA
Status: offline 		Deleted.






_____________________________

Joe Luxford
Hamilton

(in reply to jprge C.)
       Post #: 15

Page:   [1]
All Forums >> RC Airplanes >> Pylon Universe - RC Pylon Racing >> QM-40 Racing >> Proper liner/head spacing for Nelson QM40
Page: [1]





Jump to: