RunRyder RC
 1  Topic Subscribe
WATCH
 1 page 1389 views POST REPLY
ProModeler Scorpion Power
HelicopterEngines Plugs Mufflers Fuel › Different head shim for OS91 HZ PS with 30% nitro?
06-01-2010 08:26 AM  7 years agoPost 1
Papabill

Senior Heliman

Athens, Greece

My Posts: All  Forum  Topic

Hi guys
I bought a used OS 91 HZ PS.
Can someone tell me if I have to use different head shimms if I use 20% or 30% nitro fuel?
And what thickness, which part number?
Or I just have to use different needle settings?
Thanks!

GAUI X3 - LOGO 550SX

PM  EMAIL  GALLERY  Attn:RR
06-01-2010 09:36 AM  7 years agoPost 2
chickens2252

Senior Heliman

Okinawa

My Posts: All  Forum  Topic

Head shimming is a performance technique and unnecessary. You can safely run up to 30% all stock motors that I am aware of. Feel free to check the manual to confirm.

Because these motors ignite from compression shimming the head serves to change the ignition timing. This can improve performance when changing fuels, altitude or even temperature. But for most, including myself, it is not worth the effort.

PM  EMAIL  GALLERY  Attn:RR
06-01-2010 05:15 PM  7 years agoPost 3
brandov2

Senior Heliman

az

My Posts: All  Forum  Topic

They come with a 1 mm shim installed ..It comes with a spare 2mm I myself use the 2mm only shim 30%..Some friends just left the 1mm shim in with 30%..We cant really tell a difference. they all tune different anyways..Some guys run both shims 3mm total and like it.. Just depends on several factors. With 30% the 2mm shim is what os recommends.

PM  EMAIL  GALLERY  Attn:RR
06-01-2010 09:43 PM  7 years agoPost 4
Papabill

Senior Heliman

Athens, Greece

My Posts: All  Forum  Topic

Ok guys! Thank you very much for your answers!!

GAUI X3 - LOGO 550SX

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 04:49 AM  7 years agoPost 5
jsenicka

rrProfessor

Eagle River, WI

My Posts: All  Forum  Topic

depend on fuel used, and base altitude.
CY30 at sea level needs a lot of shim (I run two .2 and one .1mm shims). Other 30% fuels with a lighter oil package can get away with less.

Jim Senicka
Team Manager, GrandRC Flight Team

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 05:50 AM  7 years agoPost 6
blingbling rapt

Senior Heliman

Sweden

My Posts: All  Forum  Topic

Brandov2
Do you and your friends still using the pump?

Richard

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 05:56 AM  7 years agoPost 7
Dr.Ben

rrMaster

Richmond, VA, USA

My Posts: All  Forum  Topic

Correct Jim.

The assumption that all stock 91 engines are fine on 30% with the same shimming is false, and calling the process "a performance technique" and "unnecessary" underestimates its mandate with some fuels, mufflers, and geographies in order to achieve reliable needle settings, smooth running, and reasonable glow plug longevity. We played around with multiple shim combinations when the HZ was in prototype stage. The stock set up works well in the majority of fuels, but I can assure you that there are at least two fuels on the market that may demand more shim.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 06:33 AM  7 years agoPost 8
brandov2

Senior Heliman

az

My Posts: All  Forum  Topic

BlingBling
Ya up until recently my buddy had a pumped version with the stock shim .. He converted to the regulator and left it alone stock shim.. I have the regulated version. I ran the 2mm right off the bat and they seem pretty close tuning wise, we are running 30% torco .Was going to try the 2mm and 1mm together and see..But it runs to good to mess with

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 07:00 AM  7 years agoPost 9
Papabill

Senior Heliman

Athens, Greece

My Posts: All  Forum  Topic

I will also try the 2mm plus 1mm shim. I use Optifuel 30% and I ussually fly at sealevel.

Can anyone give me the part number number for 1mm shim?
Thanks.

GAUI X3 - LOGO 550SX

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 07:05 AM  7 years agoPost 10
brandov2

Senior Heliman

az

My Posts: All  Forum  Topic

Papa Bill
the 0.1 shim pn is 29061405 well they actually call it a head gasket

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 07:32 AM  7 years agoPost 11
Papabill

Senior Heliman

Athens, Greece

My Posts: All  Forum  Topic

Thanks brandov2

GAUI X3 - LOGO 550SX

PM  EMAIL  GALLERY  Attn:RR
06-03-2010 06:14 PM  7 years agoPost 12
outhouse

Veteran

auburn ca

My Posts: All  Forum  Topic

its common practice to use more then one shim as drben stated.

I use 2 thick shims and 1 this. heres why

it will fly with 1 stock thick shim but it will give you a very this line between slobbering rich and to lean.

the more shims you add the easier it is to tune as the motor does smooth out a hair and broadens the tuning gap

PM  EMAIL  Attn:RR
WATCH
 1 page 1389 views POST REPLY
ProModeler Scorpion Power
HelicopterEngines Plugs Mufflers Fuel › Different head shim for OS91 HZ PS with 30% nitro?
 Print TOPIC  Make Suggestion 

 1  Topic Subscribe

Saturday, August 19 - 9:45 pm - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online