When you cycle the Marvel Schebler throttle arm, it squirts quite a stream of fuel in to the manifold. Three strokes of the throttle probably delivers an ounce or more of fuel. I know that fuel in the combustion chamber should ignite faster than fuel in the intake manifold, but even cold, my C180 fires within one to three rotations of the prop every time without priming it with the six-point system. The primer and it's lines seem like unnecessary equipment. Does anyone know if it is required as part of the minimum equipment list to have the primer and the associated plumbing installed in a Cessna 180? Does anyone know of a scenario where I would regret removing this and plugging the ports in the cylinder heads? Simplifying without loss of function is an ideal situation.

It can be *really* easy to flood with the throttle. If you miss the catch on the first try, and have to start again with a couple more shots of throttle, and you'll have a nice puddle on the ground. I went back to using the primer. It's a 6 point,and if I over-prime, it is a simple matter of cranking through several blades and it will catch eventually.

Either way works, but I think there is less fire hazard with a primer personally. Even using two throttle strokes and waiting means fuel seeps out of my carb unless I am cranking right away.

I used to work the gas island and truck at the old Palo Alto airport in the 60s.
Saw a couple catch fire when a throttle jockey would wang the accelerator pump a few times before hitting the starter.

I often do a restart with the accelerator pump, but only after the prop starts turning.

I was "fireman" on the left side of one of those new tri-motor replacements at the Watsonville Airshow one day when Len Von Clem flooded the left engine and caught it on fire. I pulled the pin on the extinquisher and looked a Len, he kept on cranking and shaking his head no. It finally did start but was close. Scared the poop outa me to see fire burning inside that large exhaust oft hat brand new million dollar plus plane.

Stay safe

PS: The chemical in most of the 'dry powder' extinquishers is highly corrosive.

I have no primer on my cub, but it isn't nearly as thirsty when cold as a big Continental. I would urge you to consult with someone who has rebuilt O-470's with any amount of regularity. I think you will find out that the vast majority of those they see show signs of having induction fires in their lives. Most often the owner's were not aware, and were just a 'puddle' away from torching the front half of their airplane. Prior to doing a little homework, I thought I might remove mine as well, I have since changed that thought process.

Take care, Rob

My '73 182P has an O-470R and I always give it 3 primes at a cold start, and no primes when hot. It fires right up every time immediately without pumping the throttle. My cousin and I bought a '61 180D with the O-470R, and if you prime it at all, cold or hot, it'll make you hate life. NO start. It goes with a quick throttle pump and immediate cranking. I don't know if the carb is different, but the 180 doesn't appreciate my 182 start method at all.

A few years ago I was on a 135 checkride in the 180 and the engine actually quit on a "simulated" engine out landing from downwind. Made it to the threshold of the runway by the skin of my teeth and spent almost 15 minutes on the runway sweating bullets trying to restart the damned POS. I passed, but the next day I had to do a checkride in the 207 at my other job and redeemed myself.

The accelerator pump squirts the fuel into the throat of the carb, not the manifold. That's why the fuel runs out of the airbox and drips on the ground right away. It's there for sudden power applications from idle power, I don't think it was ever meant for aiding engine start...

Been operating 470's for thirty years. ONLY fire I had was when pumping a C 180 to start it.
Quick reacting neighbor put it out with Halon. Only some scat tube damaged.
My current 182 only primes one cylinder. It hits below zero at times here at 5000 ft. in winter.
Three shots of prime and she goes. Never pump the throttle. If it starts to die... shoot some more prime in it. Rather than plugging up all six, pick a few you don't want and plug them.
Fire is no fun unless camping. See my main photo collection ! Good luck