Hard starting A-75 with slick impulse mags

[SteveR]

Lately my A-75 has been a little hard to start. Since I got it (about two years ago) it always started on the 6th or 7th pull. Starting early last winter though, it started getting hard to start. I attributed this to the temperature & not having a primer (which were definately factors, it won't start below 45*F without significant preheating).

I've flown a couple of times this week though, with temps in the 70s, and it is taking from 25-45 blades to get it started. Hot, it started on the second pull like it always has. Any tips? Again, I have two newere Slick impulse mags & no primer. I realize not having a primer complicates things, but in the past it always very reliably started on the 6th or 7th blade.

Thanks!

[M Towsley]

Re: Hard starting A-75 with slick impulse mags

Steve,

My A-65/75 usually starts first pull. You can do some searching in the archives, but I usually close the throttle and pull it through about four blades. Having it at idle helps pull fuel through and load each cylinder. Barely crack the throttle, mags hot and it almost always starts first pull. You may have some other issues, perhaps mixture or something. The only time I have to prime is very cold conditions. I have had two different A-65's and they both behaved the same way so I'm not sure what is going on. I'm sure you will get many other suggestions but mine is a consistent starter. Good luck!

[flybikefarm]

Re: Hard starting A-75 with slick impulse mags

Sounds to me like an induction leak. My 65 also starts almost ever time on the first pull. I don't need to prime, just throttle closed pull it thru four or five times with mags off, then make mags hot. George

[Frank DeBartolo]

Re: Hard starting A-75 with slick impulse mags

Mine starts like Marty's. I never use the primer except when real cold. I usually give it six to seven blades to prime the engine and then it starts on the first blade after activating the mag switch.

Frank
N43684

[n6346m]

Re: Hard starting A-75 with slick impulse mags

I too can boast about an easy starting A-65. Since my L-2b spent most of its adult life in California it did not have a primer or cabin heater when I purchased it, a situation I had to remedy when I brought it up to Alaska. I replaced the old Scintillas with freshly rebuilt Bendixes with only the right one having the impulse coupler. You have to start it with only the right mag on because the freshly rebuilt left mag will quite often want to fire before the impulsed mag giving a kick in the prop at the wrong time. Another easy starting technique I have developed is that when shutting down the engine I let it idle at 800 RPM just before turning off the mags. After I make sure that the throttle has not obviously been moved, I don't touch it for starting. My cold engine will usually start on the first pull and idle at about 600 RPM until I can reach in and turn the mag switch to both and turn the fuel valve on. If the engine is warm and I plan a restart in the near future I idle it down at 700 RPM. Everybody has their own technique that works for them. I learned mine through trial and error and experiences of others. Just a thought.
Bob

[dedrekon]

Re: Hard starting A-75 with slick impulse mags

Generally speaking, those little Continental are very easy starters. Mine has no impulse couplers and usually starts on the first pull (after priming).

I would make sure my prop was indexed in the right spot....this can make a HUGE difference in how much ompf you get on the pull. If that's not the problem, I would look to an air leak, as noted by George.

v

[dewhitaker]

Re: Hard starting A-75 with slick impulse mags

Another possibility could be frosted plugs. If the aircraft is in a cold hanger, and then pulled out to the increasing air temperature, the mass of cold engine cylinders could cause sweating. This would be aggrevated by pulling the blades through many times to prime it. The air sucked in would sweat moisture internally and the plugs would become damp. Try letting the aircraft warm up before attempting to start. Installing or fixing the primer would help.

[SteveR]

Re: Hard starting A-75 with slick impulse mags

Thanks for the tips so far everyone. Went up this evening, & it took around 25 pulls to start. Temperature was around 70*F, even in the hangar.

If it was an induction leak, wouldn't this also likely cause a high idle? With the throttle closed, I believe the idle is around 600RPM (that may not be accurate, but it idles as low as it always has).

Maybe I'm opening the throttle too much, allowing too much air and dilluting the air/fuel mix? Since I began having more difficult starts due to cold weather I've been cracking the throttle to about 1,100RPM (tail is always tied down). Maybe I need to try it with the throttle closed or very near closed (800RPM as someone suggested)?

Thanks for the tips. It would be nice if it was my poor technique & not mag timing or another issue.

[dedrekon]

Re: Hard starting A-75 with slick impulse mags

Steve,
I pulled the prop off mine to repaint the nose bowl awhile back and when we put the prop back on we missed the proper index (position) by ONE bolt and it took 10-20 pulls to get it started every time.
On the advice of the magnificent, beneficent and super intelligent members here, we moved the prop to the proper position and, voila, it started on the first pull and does nearly every time.
I can't imagine starting with no primer.....my next door hangar neighbor pulled the primer off his Champ on the advice of a pal, and spent two months of sheer frustration trying to start it before he reinstalled the primer and kicked his advisor in the @$$. No offense intended towards the no primer crew.

v

[Pearson]

Re: Hard starting A-75 with slick impulse mags

Steve,

I have an A-65 Cont with a Stromberg carb on my Taylorcraft. I do not have a primer. I prime my engine by pulling it through several blades with the fuel on. The number of blades depends on air temp and how long since the engine has been run.

If it is 70 degrees and I haven't ran the engine that day, I pull through about 6-7 blades with the fuel on and the throttle cracked 1/8". By the 6th or 7th blade I can hear a squishy sound from the fuel in the carb. Then I CLOSE the throttle completely. It usually starts on the first pull, but I have to get to the throttle imeadiately to crack it open just a hair. I do that by starting on the passenger side from behind the prop.

This is what works for me. I began closing the throttle completely after reading about the Stromberg carb in a book from Sacramento Sky Ranch. Prior to that I had always started with the throttle cracked 1/8". Once I began starting with the throttle completely closed, my engine was much easier to start.

[Dennis Keels]

Re: Hard starting A-75 with slick impulse mags

What does the position of the prop have to do with starting?

[Acroeric]

Re: Hard starting A-75 with slick impulse mags

The position of the prop has alot to do with it- mainly because you get the most rotation(more force due to the correct position- helps you spin it a bit faster) when it is properly indexed. This extra inertia helps overcome the compression stroke of the next cylinder if it doesn't fire completely. This is especially important with wood props.
On another note- it can be pretty dangerous if it is not indexed because it puts you at an awkward position when starting.

[alwaysoar]

Re: Hard starting A-75 with slick impulse mags

How's your compression?

[Ragwing nut]

Re: Hard starting A-75 with slick impulse mags

Have you double checked you timing?

Mike

[SteveR]

Re: Hard starting A-75 with slick impulse mags

How's your compression?

Compression was great at the last annual, all in the seventies, with three at 75.

Mike, I don't know about the mag timing, and I'm not confident enough to check it myself. I like to at least watch someone else do it first, or have someone watch me do it.

I'm now leaning towards the mag timing or opening the throttle too far when trying to start it. I'll try to start it sometime this week with the throttle closed and see if that is my problem

Thanks for the tips!