From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On Behalf Of Jeff Whaley
Sent: Monday, December 01, 2008 12:14 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: Front Nut, Thermostat and Coolant Intake hose was : [FlyRotary] Re: Hot first flight

Hi Ed, I don’t want to change the main e-shaft pulley … I was thinking of changing the ALTERNATOR double-groove pulley … the belt got jammed in the alternator pulley; the alternator and top cowling were powdered with rubber residue.

Jeff

 

 

FONT NUT CAUTION

 

Jeff, as Tracy mentioned – delay changing the main pulley until a bit later (unless its clear there is a defect in it) because if you DO let the thrust bearing slip off its shoulder on the E shaft – it’s a minimum of taking the front cover off the engine (next to firewall) to get to it.  In most cases, due to limited space under the cowl and motor mounts, you end up taking the engine off the aircraft.  That’s not fun any time and I imagine even less so with temps in the 30F range.

 

BUT, if you decide you HAVE to replace the main pulley without removing the engine, here is a suggestion.

 

Raise the tail of your aircraft as high in the air as you safely can.  This will tend to keep the thrust bearing toward the rear of the engine (front of aircraft) where it rests against a spacer.  That way the shock of an impact wrench will not have as much tendency to “walk” the bearing forward and off its shoulder.  No guarantee it won’t get out of position – just a bit less likely - than if the nose is up.

 

There are some instructions in the Mazda manual or somewhere that tells you how to determine if the thrust bearing has falling out of position by taking some measurements based on how far you can get the pulley nut back on the shaft  – but, I can’t  recall  at the moment where they and you really don’t want to go there at this time in any case.

 

THERMOSTAT

 

I believe I read about the loss of efficiency by leaving out the plug in one of Racing Beat’s old technical catalogs and I am fairly certain they mentioned 20%.  Well, I looked in one of their old catalogs and while I did not find a specific percentage mentioned (at least in my quick search), this is a quote from them:

Quote :

“

7.       Mazda’s water thermostat is a “by-pass” type (apparently referring to the ½” by-pass  hole).  Therefore, if it is removed for racing, the hole below it MUST be plugged……

… NOTE:  The thermostat should be removed and the bypass plugged for racing.  Do not use restrictors in the system.  Free Flow is best.

 

“

RADIATOR INTAKE HOSE

 

Another thing Racing Beat cautions about - is making certain that the radiator hose on the suction side is the type that has a spring coiled in side or is otherwise stiff enough to resist collapsing under the suction of the water pump.  If that happens, of courses, your coolant flowed is seriously impeded.

 

The hose may be able to resist the suction at idle or low rpm, but may not at the higher rpm.  If you squeeze the hose and can  deform it with your hand pressure , then it is likely too flimsy to serve as the radiator hose on the intake side of the pump.

 

You are 99% there, Jeff.  So no rash action, just take it one step at a time {:>) – easy for me to say.