hand prop tune

[swoeric]

So it is a 85hp with electric. Looking to have hand prop reliability. it starts easy enough with the starter after 10 or so revolutions. I have read through all of the hand propping procedures here. tried a few and not much luck.

I haven't seen any threads giving advice on tuning for optimum easy of starting. so are there any tips or tricks that have worked before.

Eric

[flyguy]

Re: hand prop tune

Define tuning, as you mean it.
Darryl

[Ragwing nut]

Re: hand prop tune

Prop ideally should be 90* to the crank throw on the small continental. TO hand prop, with the cylinder coming up on compression should be sitting approximately 10 o clock position.

If it is requiring 10 blade to start with starter, it will be difficult to start by hand. You need to figure out the engines "ritual" that it likes to start. I normally start with 2 shots of prime on a short throw primer, pull engine through 4-6 blades with the mags off, throttle closed, turn mag switch on both since you have a c-85-12, and engage the armstong starter.

[swoeric]

Re: hand prop tune

i am more familiar with the auto community with plenty of leeway for adjustments. I consider air leaks in the intake track to be common sense. but is there a float level throttle blade angle timing or any adjustments that can be made to the engine for easier starting.

I have read a few post here and see that some are capable of starting on one flip of the prop. I have found that one shot of prime up to 3 shots make no difference in starting with the starter in these cooler temps.

[Pearson]

Re: hand prop tune

i am more familiar with the auto community with plenty of leeway for adjustments. I consider air leaks in the intake track to be common sense. but is there a float level throttle blade angle timing or any adjustments that can be made to the engine for easier starting.

I have read a few post here and see that some are capable of starting on one flip of the prop. I have found that one shot of prime up to 3 shots make no difference in starting with the starter in these cooler temps.

Eric,

You can't tweak the timing, or anything else on your plane like you can on a car. I don't know what the timing is supposed to be on a C85, but whatever the number, that is what it needs to be.

I would spend 20-30 minutes checking for common mechanical problems before spending too much time trying to hand crank it. I would go over all the clamps on the air intake tubes, snug up all the nuts holding the carb on, and verify that the primer is indeed squirting. Take the line off where it goes into the intake spider and while holding the end of the line in a container, have someone give it one squirt. A lot of primers you have to wait a second or two after you get the knob all the way out. That gives the fuel time to fill up the chamber before you push it out to the engine. While your "under the hood" make sure the air filter is not clogged up or the carb heat baffle lodged in the airway at a bad angle choking off the air.

Mike mentioned the "ritual" for your engine. Every one of these little Continentals has it's own set of steps that seem to work only for that engine, hence the "ritual".

I have an A65 Continental. I have started it in very cold weather and also fairly hot. I can start it almost every time on the first flick because I have learned it's ritual.

Experiment with different amounts of prime. Keep in mind that the colder the engine is, the more prime it is going to need. Also, if the engine has been run in the last 3-4 hours, you MAY not need to prime at all. It depends on YOUR engine. On my A65, the way I can tell when I have enough prime is when fuel starts drippiing out of the airbox. If I prime it too much, turning the prop backwards with the mags off works for me.

The C85 has a completely different carburetor than my A65, but you might want to try starting with the throttle completely closed, as in all the way closed. I am not that familiar with the carb on the C85, but on the A65 it draws the fuel from a different ciruit with the throttle closed verses cracked an eigth inch.

If it is under 40*, you are going to need a pretty good amount of prime. Without knowing how long a stroke your primer is, it is hard to say exactly how many shots. I have seen engines take 8+ shots to start on a cold day. I have also seen engines that needed an additional slow shot after it was started in order to keep running. But that was only when it was down in the single digits.

The MAIN thing to keep in mind when trying to hand crank is safety first. Don't let the engine get you frustrated where you forget a step, or forget to turn off the mags. Get someone to help or tie it down.

[mulwyk]

Re: hand prop tune

10 revolutions to start a continental is not good. Maybe your primer isn't working. Check the drip.

Do you have impulse couplings on your mags?

Properly operating impulse couplings make a big, big difference in hand starting. Dual impulse couplings will start first blade nearly every time.

[mohawktipi]

Re: hand prop tune

I just upgraded my L-2 to a C-85 form an A-65. With the A-65 (dual impulse , Slick mags) I would hand turn the engine through 8 blades turn on the mags and it usually started on the first pull. Never more than 2. Although I have electric start now (dual impulse, Slick mags), I still use the same procedures I used in the A-65. Hand turn the engine through 8 plades. Climb in turn on the mags and hit the starter. Starts on one or two blades. Both engines were set (timed) to the recommendations from SLick for the engine and mag type.

[jim cooper]

Re: hand prop tune

What kind of mags you got? old? New slick impulse mags (or mag) make BIG difference provided carb. is in good shape. good spark and correct gas.....its gotta go! I wore myself out with old bendix mags on a cub. New Slicks...it fired right off. (Let me add here that I am not a mechanic or authority.)JC

[swoeric]

Re: hand prop tune

I the mags are slick, at least one is impulse. I can hear it when the motor shuts down. I checked the internet about the carb and learned quite a bit. I was probably my own worse enemy. I looked over the idle circuit and see that the motor was made to start at 500rpm. you dont pull any fuel from the idle circuit with the throttle open and i had it cracked open just a bit. I also got the lay out of the primer and see that it is not directly into a cylinder. also if the prop is spun too fast you will not get good pull from the idle circuit but you may not be spinning it fast enough to get it from the nozzle either. It may be way easier to start if i was in my own way. Unfortunately I am out of town and can't check till tomorrow. as i sit here in meetings applying what we learned from the production of aircraft past to our assembly goal of one f35 a day and arguing whether strain gauges or brackets need installed first I cant help but think the recipe for the best flying machine was a tcraft perfected many years ago. I am dying to put my new learned knowledge to the test. I'll report asap

[swoeric]

Re: hand prop tune

so i just got it to work no throttle turn prop 6-8 blades 32* two shots prime started second flip. Thank you all i was able to find a posting here that gave a link to cessna 140 forum and they had excellent stromberg tech files

Eric

[astjp2]

Re: hand prop tune

I am running 2 primers into the aft 2 cylinders, ran both the bendix bread box mags and slicks. When it was cold 3 shots of primer and it started on the second pull with either mag. Tim