My 1973 Skyhawk has the 360/180 hp engine carburated.
When the engine is hot it is difficult to start.
My procedure is master switch battery side on, fuel pump on. Prime throttle 3
times. Fuel pump off, turn starter while advancing the throttle.
Today she would not fire and the battery went south.

Any recommendations, suggestions.
Will check timing and Magnetos tomorrow.
Hank N1441P

"Hankal" > wrote in message
...
> My 1973 Skyhawk has the 360/180 hp engine carburated.
> When the engine is hot it is difficult to start.
> My procedure is master switch battery side on, fuel pump on. Prime
throttle 3
> times. Fuel pump off, turn starter while advancing the throttle.
> Today she would not fire and the battery went south.

Sounds to me like you are over-priming the engine and you have vapor lock.

If the engine does not start within a couple of turns of the propeller it is
not going to help things to just keep cranking it. Pay close attention to
starter recycle times as described in the POH -- wait 30 seconds before a
second attempt and several minutes before a third.

I would not prime the engine at all if it is hot. I would keep the fuel pump
on during the start in order to keep fuel moving through the system so that
you don't get vapor lock. I might also start with the throttle about half
open, possibly the primer out. While cranking the engine, push the primer
slowly in to give it a small amount of fuel. Pull the throttle back to 1000
once the engine fires.

Lycoming says "Priming can best be accomplished with an engine priming
system, as opposed to use of the throttle." Later in the same paragraph,
they say "Lycoming engines of more than 118 hp have an throttle pump which
can be used for priming under moderate ambient (I would underline that word
if I could) temperature conditions while turning the engine with the
starter."

Ambient is outside air, as you know, and the procedure discussed is an
initial start, not a hot engine procedure. I always assume that a hot
engine's fuel lines are still full after the last shutdown, and don't prime
a hot engine at all.

But I don't have the book on your airplane/engine combination...
Bob Gardner
"Hankal" > wrote in message
...
> My 1973 Skyhawk has the 360/180 hp engine carburated.
> When the engine is hot it is difficult to start.
> My procedure is master switch battery side on, fuel pump on. Prime
throttle 3
> times. Fuel pump off, turn starter while advancing the throttle.
> Today she would not fire and the battery went south.
>
> Any recommendations, suggestions.
> Will check timing and Magnetos tomorrow.
> Hank N1441P

In GENERAL, and not specific to your engine, my procedure is to shut the engine
down with the magnetos and run the throttle in to full as the engine stops.
Then pull the mixture and throttle back as normal.

Never takes more than a blade or two in my experience. If you don't anticipate
starting it again for a couple of hours, do the standard mixture cutoff
procedure.

Jim


(Hankal)
shared these priceless pearls of wisdom:

->My 1973 Skyhawk has the 360/180 hp engine carburated.
->When the engine is hot it is difficult to start.
->My procedure is master switch battery side on, fuel pump on. Prime throttle 3
->times. Fuel pump off, turn starter while advancing the throttle.
->Today she would not fire and the battery went south.
->
->Any recommendations, suggestions.
->Will check timing and Magnetos tomorrow.
->Hank N1441P

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

On 28 Mar 2004 22:33:28 GMT, (Hankal) wrote:

>My 1973 Skyhawk has the 360/180 hp engine carburated.
>When the engine is hot it is difficult to start.
>My procedure is master switch battery side on, fuel pump on. Prime throttle 3
>times. Fuel pump off, turn starter while advancing the throttle.
>Today she would not fire and the battery went south.
>
>Any recommendations, suggestions.
>Will check timing and Magnetos tomorrow.
>Hank N1441P

You have an electrical fuel pump??

I've never seen one on a 172.

Mike Weller

"Mike Weller" > wrote in message
s.com...
> On 28 Mar 2004 22:33:28 GMT, (Hankal) wrote:
>
> >My 1973 Skyhawk has the 360/180 hp engine carburated.
> >When the engine is hot it is difficult to start.
> >My procedure is master switch battery side on, fuel pump on. Prime
throttle 3
> >times. Fuel pump off, turn starter while advancing the throttle.
> >Today she would not fire and the battery went south.
> >
> >Any recommendations, suggestions.
> >Will check timing and Magnetos tomorrow.
> >Hank N1441P
>
> You have an electrical fuel pump??
>
> I've never seen one on a 172.
>

You find them in at least some 180 hp engine upgrades and standard equipment
in all the new fuel injected 172s. The electrical fuel pump will be a backup
for the engine fuel pump, which most 172s don't have, either. I guess
gravity feed just does not give you the fuel pressure you need to feed a 180
hp engine, but I suppose there are others around here who would know a lot
more about that.

Several companies, including Penn Yan, Air Plains, and Avcon sell conversion
kits and/or STCs for 180 hp 172 upgrades. Some of the conversions include a
constant speed prop. The cost will typically run about $30,000 for a fixed
pitch conversion.

From what I have heard, the constant speed prop adds about thirty pounds and
does not help performance much. Some of these conversions also require
limiting the flaps to 30 degrees. All of the conversions claim faster speed
and improved short field performance.

C J Campbell wrote:
>
> All of the conversions claim faster speed and improved short field performance.

I flew one once, back about 1989. It would cruise at 125 knots with a fixed pitch
prop. As far as short field is concerned, there was one based at Kupper when I
bought my Maule. He not only had 180 hp, but he had fancy wing tips and vortex
generators. He still needed more runway than my 160 hp Maule. Of course, the only
way I'll see 125 knots is pointed straight down. :-)

George Patterson
Treason is ne'er successful, Sir; what then be the reason? Why, if treason
be successful, Sir, then none dare call it treason.

On Mon, 29 Mar 2004 18:23:05 -0800, "C J Campbell"
> wrote:

>
>"Mike Weller" > wrote in message

>> I've never seen one on a 172.
>>
>
>You find them in at least some 180 hp engine upgrades and standard equipment
>in all the new fuel injected 172s.

Well. of course on the fuel injected new ones but I just haven't seen
that on a regular one. I stand corrected.

Mike Weller