Timing...

[N95179]

Re: Timing...

Well...instead of taking all of your advice and getting it looked at before my next flight, I spent over an hour on the beach trying to get my engine started the other night and it was worse than ever. It would fire once and then swing back a few blades, then it would be flooded. I would clear it out and it would fire again, but same old story, in the next few blades it would be dripping fuel and be flooded again. I gave up after 45 min or so and took a break. When I came back after it had cooled off more, I got it going and flew home.

I finally got it into my mechanic today. Last night I cleaned the plugs and checked the leads which made it start up a little easier, but I wanted to get an answer on those mags. The plugs were pretty clean, but they are unshielded and there was quite a bit of oil on some of the leads where they connect to the plugs, so gave them a good cleaning as well.

By the way, they are the older Bendix mags without the impulse couplings.

I don't remember the tool he used (goes into the #1 cyl and finds top center), but my mechanic checked the timing on the mags and they were dead on 30 degrees even and 29&7/8 on the other ...pretty close. We re-indexed the prop and it put the blade way too far back for an easy start so we put it back where it was to begin with.

I fired it up to check it out, and it started up good. But later when it was warm, my boss propped me at the fuel pump and again it swung back a few blades. So I'm still dealing with the same problem! I don't know where to go from here except to just deal with it.

(Sorry about not getting back to all of your replies sooner, I really appreciate them!)

Thanks

[alwaysoar]

Re: Timing...

Dear Chris--I'll say it again, new Slicks will set you back about $1050 after trade-in and rebate. Believe me, it's worth mortgaging the wife to have that sucker kick off on the first or second pull--every time. Plus you have the security of knowing they're new and won't (probably) die on you mid-flight or in some remote place. I've been there, done that with the forty-five minute propping events. No more!
Ed@BTV VT
TF 527

[Karl Rigdon]

Re: Timing...

Chris,
The SF4 Bendix mags are about as dependable as sunrise in the morning. However you cannot just pull it through TDC. You have to be very aggresive when proping. Again you have to have the inertia to get it over TDC even after the fuel mixture has started to burn and build cylinder pressure.
The investment in Slick or other impulse mags eliminates this problem. With the engine properly primed you can stand behind the prop with the right door opened and your left hand on the door frame (18"from the mag switch and throttle,your foot in front of the right tire) you can use 2 fngers to pull over TDC and it will start. I switched to Slicks years ago. The down side you cannot set the idle to 300 RPM and watch the blades go by on short field landings.
The SF4 mags are safley stored just in case.

Karl

[N96337]

Re: Timing...

Yep, you're right on the money Karl. No impulse couplings makes a whole other story of propping. Heat changes it even just a bit more. Mine runs Eisman's with impulses... I can idle down a long ways, but not like those old SF4's!!!
JH

[lfries]

Re: Timing...

My bendix are really not a cold start problem but they can be trying when the engine is warm. If I shut it down around 800-900 RPM ususlly within 30 minutes or so I can get a start on the first of second blade. After the second blade it will start but only after clearing it several time and setting the throttle for about 1200 rpm. The engine I'm putting on now has slicks so I'm looking forward to more consistent easirt hot starts.

[Armstrong]

Re: Timing...

Chris , I had Bendix mags on my Champ( no impulse on either), and what you describe on starting, was common for my hot starts in the summer(I lived in TN., hot and humid).I just got practiced at clearing floods, and while it was still a pain, I didnt spend more than 5 min starting. Is this your first warm weather( I should say warm relative to your winters) starting with this T-craft?
My T-craft has Eisemanns with an impulse on one mag and it will still spin backwards on hot starts in the summer( not everytime, but often enough).
My problem with the Eismans is humidity, if I dont blow a heat gun into each mag on humid /foggy mornings the engine will not start. Once its warmed up its fine though.
Its always something
Rob

[N95179]

Re: Timing...

Thanks! This place is an incredible resource. Sounds like I'll just keep my plugs clean and try to get a good strong pull through every time. Maybe I'll get some Slicks for it next year if I can fit them between student loan payments This is my first summer with the Taylorcraft (first plane of my own). It's teaching me tons!

My grandparents have given me access to their Cessna 170B since I was 16. He got me through the Private License and I got my Commercial license in it last spring. He had only one condition for me..."keep it on the airports" (with the exception of caribou hunting in the winters) Which was fine, but I badly wanted to go farther and do more.

I lucked out with commercial fishing last year and got the Taylorcraft. It's been a blast. I used to think the 170 was a feather until I flew a friend's T-craft. They may have weak brakes, poor visibility, cold cabins in the winters, and seats that will make the spine weap tears later on, BUT I can push them around by myself, they don't use hardly an eye drop of gas, cruise reasonably fast, or as slow as you want to, have a beautiful round tail (and a tailwheel), lots of class, a pretty sound, have the wonderful smell of oil and avgas, and they are just plain FUN!!!

Thanks again

[Armstrong]

Re: Timing...

Chris,I wish I had the smarts to buy an airplane at 21, and have a commercial license to boot.
The 170B is a great flying airplane and those flaps will get you into places you cant get out of!
When I lived in TN, off airport landings were my favorite pastime. There were so many hay fields and small islands in the lakes around me, I could land all day long, and never once at an airport( never got stuck ,but close a few times).
I fished out of Kodiak and dillingham for many years.
Rob

[Mark Julicher]

Re: Timing...

Chris,
The starting problem you are describing is dead-on for a having a coil problem. The hair-fine wire in the coil can develop an open when hot making a lot of flooding and kickbacks when trying to start. Once cooled down the mags behave nicely again. Eventually you will get stuck out with a bad mag or two.

The Slick replacement is a good idea. Conversely, you can now get coils for the SF-4 and have it overhauled (for about as much money as buying the Slicks)

In any event, you might have somebody check the resistance on your coils.

[Armstrong]

Re: Timing...

Chris,
The starting problem you are describing is dead-on for a having a coil problem. The hair-fine wire in the coil can develop an open when hot making a lot of flooding and kickbacks when trying to start. Once cooled down the mags behave nicely again. Eventually you will get stuck out with a bad mag or two.

The Slick replacement is a good idea. Conversely, you can now get coils for the SF-4 and have it overhauled (for about as much money as buying the Slicks)

In any event, you might have somebody check the resistance on your coils.

Mark, I know it was for Chris, but thanks for the suggestion. I will check mine too, And will remember it next time I see that problem in mine or someone elses. I have seen it alot.
Rob

[Forrest Barber]

Re: Timing...

I transfer that mark to the top of the flange with a chisel so I can see it. OR I usually use a timing indicator with rubber bands to the prop blades. the prop should,pull through so it fires at 8 to 7 O'Clock. If no impulse try setting left mag at 28 degrees & rt at 30 degrees , start on left mag only then switch. to both

[Len Petterson]

Re: Timing...

It is typical for all kinds of mags to be imposible to start hot, when the coil is close to complet failure.
I have experienced it in motorcycles, lawn movers, boat motors and planes.
By at least one Slick or another good mag, or try to find good coils for yours.
You are playing out there in 'no mans land" and I would hate to hear what you did not get home one day, so would your grand pa.
Most parts dealer do take Visa you know!
There is bold -----, you know the rest, if not ask Grand - pa.
Does anyone have coils to sell this fellow?
Len

[Richard Boyer]

Re: Timing...

Aircraft Spruce......I recently sent a pair of mags to a shop to get rebuilt for "the other plane". I was given a price and I had the shop send them back untouched. It was cheaper to buy a "new" remanufactured Bendix than it was to rebuild!

I do think the coils were (in)expensive though....

A replacement mag (reman) is as low as $341. I have always had slicks on my T, so I don't know which Bendix Mag is on the T.

[N95179]

Re: Timing...

I put 3 hours on the Taylorcraft yesterday with several startups and shutdowns. Played around on the McArthur River and then went to the Kustatan. It was beautiful! Probably over 70 degrees, sun shining, white sand, felt like Hawaii. I concentrated on making stronger pulls and it fired up the first or second try every time. I will see how it goes next time, but I think I'll wait til I have a problem again before going shopping for new mags. I still have these student loans to poke at.

My mechanic said he has 2 degrees to play with and still be legal on the timing and he set them both to 28 degrees. After reading what Barber said, I'll have him move the right one back to 30.

Thanks!

[whake]

Re: Timing...

Good reason o put Slick Mags on the have impulse couplings on both mags. lets it fire top dead center..