Lycoming A1A engines

flyguy44 · #1 03-06-2006, 07:11 PM

Looking for advice, guys. have a 180 hp A1A carburated engine. can't even get a spark by following Lyc. guidelines..crack throttle, no pumping. Will only start after numerous pumps. do I need primer installed, or is something a-miss? That pumping thing sounds dangerous..

szicree · #2 03-06-2006, 07:32 PM

What sort of overall health does it have? Tired motors with low compression can be hard to start.

Bob Axsom · #3 03-06-2006, 07:33 PM

I have a primer solenoid down stream of the aux pump feeding fuel directly into the cylinders through the restricted primer nipples silver soldered onto copper tubes with a butane torch (everything from Aircraft Spruce). When the engine is cold I press and hold the push-button switch for five full seconds before I engage the starter and it starts right up. When the engine is hot, as when I just landed to refuel, I use no primer whatsoever and it starts right up. If I do not prime it when it is cold, it will not start. If I prime it when it is hot it will not start. Until I hit on this combination for my O-360-A1A things were awkward with hit or miss results.

Bob Axsom

garnt.piper · #4 03-06-2006, 08:42 PM

Hi, my a1a would start without any prime, just two full pumps of the throttle when cold (rely upon accelerator pump in carb). It was new from Van's and sat around for ten years before I started it on the 'plane. I'd have a real good look for induction leaks and check the magneto timing, if you haven't already. If it has been stored the gaskets on the inlet tubes dry and shrink, and internal components of Slick mags can time expire, even with no use. I had one fail in my test phase.

good luck.

tacchi88 · #5 03-06-2006, 09:28 PM

Have you checked if your mags are in good order, plug wire in the right place, P leads not grounding, as pointed out, the health of the engine?.. Ya gotta tell us all you did.
BTW, starting without priming a carburated engine, is not a wise thing to do. These engine have the most primitive carburators known to the internal combustion engine world (updrqaft), and priming with accelerator pump simply forms a nice pool of fuel in your filter. The engine spins with the hope that air mixture as it passes the pool, is enough to start the beast, but what ever mixture reaches the cylinders, is very lean. Lean condition can and will cause a backfire, and yes, make a torch out of your bird. It has happened numerous times. Do use a primer, be it electric or mechanical.
T88

gmcjetpilot · #6 03-06-2006, 09:49 PM

Quote:

Originally Posted by flyguy44

Looking for advice, guys. have a 180 hp A1A carburated engine. can't even get a spark by following Lyc. guidelines..crack throttle, no pumping. Will only start after numerous pumps. do I need primer installed, or is something a-miss? That pumping thing sounds dangerous..

flyguy44, lots of missing info and some basics to check. Sounds like it starts but it hard to start? Is the a new thing? Was it easy now all of sudden hard to start? It also sounds like you are not priming at ALL?

In cold weather you need some kind of "prime" with a Carb engine. If you don't have a dedicated primer system (which blows raw fuel into the intake port area in a few of the cylinders) you can pump the throttle. The 360A1A has a carb with an accelerator pump, so it can be used to prime. It will blow raw fuel into the throat of the carb. The danger is fuel drips down into the airbox and in theory could be a fire hazard, if not done with some care. You can give it one or two shots with the throttle, wait 30 seconds (let it vaporize), than start. While cranking you may give it another throttle pump while cranking. Be sure after you pump the throttle, you set the throttle back to the slightly open/cracked position right away. Don't over do it because you can foul/flood the plugs.

Cold weather will cause harder starting in general due to low crank speed if the battery is weak, oil is thick or starter is weak.

As far as starting problems in general, not related to priming, you left out way to much. Has it had a history of easy/hard starting? We can guess, but the basics are you need compression, gas / air mixture (in the right proportion) and spark (strong and at the time). You can run those items down one at a time; it could be a little of many items, such as: clean the plugs, check timing, fuel quantity/pressure/quality and compression check. George

mahlon_r · #7 03-07-2006, 05:08 AM

Try pumping the throttle three or four times while cranking with the starter, during the starting sequence. This tends to get the fuel into the cylinders better then pumping the throttle before engaging the starter.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at you own risk."

flyguy44 · #8 03-07-2006, 06:30 PM

Thx for the ideas, guys. As to further info, 1 yr. old engine w/ 160 hrs. has always started fine when cold w/ 5 pumps before turning key (so says prev. owner, and its worked for me for 2 mos.) Last several flts. its crapping out on me and taking forever to start. wonder what to look for...it runs great once it starts.

Mel · #9 03-07-2006, 06:36 PM

Sounds like the last few months with my engine before the left mag died.
Replaced the mag, and everything went beck to normal.
Mel...DAR

gmcjetpilot · #10 03-07-2006, 08:22 PM

Quote:

Originally Posted by flyguy44

Thx for the ideas, guys. As to further info, 1 yr. old engine w/ 160 hrs. has always started fine when cold w/ 5 pumps before turning key (so says prev. owner, and its worked for me for 2 mos.) Last several flts. its crapping out on me and taking forever to start. wonder what to look for...it runs great once it starts.

Here is what Lycoming says about cold weather starting and number of prime pumps (not throttle).

Lycoming article, priming cold weather

Go down about 14 paragraphs to number of pumps on the primer. Lots of GOOD INFO that may help.

5 PUMPS of what, primer or throttle? I think 5 is a little overkill. If you are using the throttle, that's a lot of raw fuel in your filter. If you have a vans airbox you should have a little drain hole. That hole will allow fuel to drip into the cowl and down to the ground. At best a waste at worse you can wash the filter in fuel (can't be good) and potentially have a fire hazard. Even if you are doing this 5 PUMPS with a primer pump (less of a fire hazard), you are washing lots of fuel into the cylinders which can dilute the oil film and cause wear, not to mention flooding and fouling of the plugs.

Try just two throttle PUMPS before cranking and a couple while cranking like Mahlon suggested in very cold weather. Since it's a new problem, I would look into what Mel suggest with the MAG. Good Luck. G