Thorp T-18 Mutual Aid Society
Thorp T-18 Mutual Aid Society
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 Starting procedure

My starting procedure with a carb on a 150 Lyc is similar. I crank the engine and then while it's turning over6 I pump the throttle twice and it always starts even in cold weather. Pumping the throttle while the engine is turning over reduces the chances for a backfire in the airbox due to puddling of gas there.


Joe Gauthier


-----Original Message-----



Sent: Wed6 Oct 76 2009 9:50 am

Subject: Re: [ThorpList] Missing Fuel

I do not have a primer on my Thorp.  My starting procedure is the same as Bill's other than I pump the throttle 3 or 4 times and usually have to pump it an inch or so (once or twice) after it starts too keep it running when cold.


When engine is warm I just use full rich and starter and about a 1/2 inch of throttle but no pumping.  I have never had a problem with hot starts (knock on wood) it starts much better hot than cold.  Maybe my idle mixture is too lean???


Do you have a fuel pump or gravity flow?


Matt Smith

Des Moines6 IA




-------------- Original message from Bill Williams <>: --------------


N30WW has a carburetor6 starting sequence; fuel mixture full rich6 pump the throttle 2 or 3 times. Start the engine. After start up6 lean the mixture until a RPM rise.  The HA6 carb and others have an accelerator pump that will prime the engine. Some builders elect not to install a primer for this reason. The only time I use the primer is when I have not flown for several weeks.

Disconnect the primer line from the primer6 plug it and try priming6 the plunger will move very little. If the plunger moves6 then the check valve or O rings are leaking.

--- On Wed6 10/7/096 <> wrote:

From: <>

Subject: [ThorpList] Missing Fuel

To: "hurant karibian" <>

Date: Wednesday6 October 76 20096 12:47 AM


My primer had two leather cup seals but the front one disintergrated so I made a two "O" ring piston to replace it and it works fine. I stated that fuel came out of the primer line when I disconnected it and when the engine sets for two hours I no longer consider it hot.(I don't use the drive-through for my $100.00 hamburgers) My engine is carbureted so there isn't the injection problem. If you use the mixture cutoff to kill the engine6 where does it get the fuel to start with the mixture still in cutoff? My Honda starter spins the prop so fast that I could almost taxi so I was thinking maybe its skipping the impulse coupling but no fuel in the cylinder put an end to that thought. I think I will try replacing one of the cylinder primer fitting with a straight fitting so it will squirt instead of spray.