Author Topic: What makes an engine easy to start? (Read 4441 times)

frank mccune · « **on:** October 27, 2015, 05:27:31 PM »

Hi All:

I have to ask this question as I become intolerant of engines that are difficult to start. My test is finger flipping which in the time of electric starters may not be valid. The fuel and ignition items are the same for all engines.

Is it that I have discovered the "magic" starting drill for some engines and have not for others? All engines have great piston to cylinder fits and a careful break in but some just will not start! These go into my junk drawer.

What makes an engine easy to start? Conversely, what makes an engine very difficult to start? This question must be tempered with the knowledge that the engine owners have a vast amount of experience and knowledge in starting glow engines.

Any thoughts or suggestions?

Tia,

Frank McCune

dennis lipsett · « **Reply #1 on:** October 27, 2015, 06:56:06 PM »

Find the starting drill, follow the drill ,deviate from the drill at your own risk. Works 99% of the time.

Dan McEntee · « **Reply #2 on:** October 27, 2015, 08:20:58 PM »

All engines have their own particular routine for starting that you just have to figure out. It helps to start with good fuel, good battery, good glow plug. Figure out how many time to choke it and for warm and cold weather. Most of the time, you know you are there when you firmly grasp the prop to pul it through after priming and attach the glow battery, and you feel the "bump" of the engine trying to fire off that prime. Then you know it's alive! This little thrill is what keeps me from going electric! When you know your engine, and you prime it correctly, attach the battery and get that bump, you know it's ready for action and a 1 flip start should follow.
Type at you later,
Dan McEntee

Air Ministry . · « **Reply #3 on:** October 27, 2015, 10:22:32 PM »

A Well Charged Battery , and Fresh Fuel .

Sucked in fuel plastic one gaLLON THINGS MIGHT INDICATE THE STUFFS HAD IT.
nO nITRO IN WINTER & MAYBE YOU NEED nITRO fUEL FOR THE prime TO GET IT TO KICK .

Darn CaPsLoCk .

Little Diesels your best to find the ' Fire Point ' on compression on a prime, before fueling .

Glows often a burp on a Prime before Fueling gets it cleared . a well Oiled ( for parking)
sucker can benefit from removeing the plug , a healthy ( 1/2 Oz. ) intake prime ,
and belting it thru till its not sopping , then replacing the plug & firing up .

Storage Oil if generous keeps saturateing the plug . a healthy Battery might clear it ,
but likely burns it and cokes up . Might stuff the plugs ??

frank mccune · « **Reply #4 on:** October 28, 2015, 07:09:01 AM »

Hello Matt:

I think that you are on to something! Remember I said that a plug will not work after it has been sitting for awhile drenched in after run oil? Well this year I have been flushing my engines with carb cleaner or fresh fuel prior to running them. I have noticed that starting was much easier than when I did not do this. It may the air tool oil or the ATF that I use for storage is contaminating the glow plug element when they have not been flushed out of the engine prior to starting. As you have probably guessed, I aint very smart and your post gave me the impetus to connect the dots regarding my starting drill. Come to think about it more, the engines that I have been using this year have all been one flip starters IF they had been flushed clean prior to starting. At first, I blamed the air tool oil for not burning which may or may not been accurate, but my problems appeared to cease when I flushed the engines prior to starting them. Also, if I flush the engines clean of oil residue, glow plugs seem to last forever.

Good grief, perhaps many of the engines in my junk drawer are not all that bad. I see tests in my future. Lol

Brett Buck · « **Reply #5 on:** October 28, 2015, 11:05:42 AM »

Quote from: frank mccune on October 28, 2015, 07:09:01 AM

Hello Matt:

I think that you are on to something! Remember I said that a plug will not work after it has been sitting for awhile drenched in after run oil? Well this year I have been flushing my engines with carb cleaner or fresh fuel prior to running them. I have noticed that starting was much easier than when I did not do this. It may the air tool oil or the ATF that I use for storage is contaminating the glow plug element when they have not been flushed out of the engine prior to starting. As you have probably guessed, I aint very smart and your post gave me the impetus to connect the dots regarding my starting drill. Come to think about it more, the engines that I have been using this year have all been one flip starters IF they had been flushed clean prior to starting. At first, I blamed the air tool oil for not burning which may or may not been accurate, but my problems appeared to cease when I flushed the engines prior to starting them. Also, if I flush the engines clean of oil residue, glow plugs seem to last forever.

Good grief, perhaps many of the engines in my junk drawer are not all that bad. I see tests in my future. Lol

Maybe, but I have in the past done something similar and aside from taking most of a flight to burn off and smelling funny, I haven't had any issues with large quantities of air tool oil. It was really amazing how long it lasted, well into the first flight of the day you could still smell it.

Brett

Tim Wescott · « **Reply #6 on:** October 28, 2015, 11:11:06 AM »

When in doubt, change the plug. Then throw out the old one.

If your budget is tight enough that plugs are dear, keep one new as a diagnostic aid -- if swapping it in doesn't fix the problem, swap it back out for the old one and keep the 'newish' one to test the next time. If swapping a plug out does fix a problem then take the bad one and throw it out. The last thing you need is a bunch of questionable plugs that you madly swap in and out trying to find magic.

Also: use the right plugs. I'm not sure how much difference it makes to starting, but CL engines seem to want hot plugs -- don't just buy random RC stuff; make sure you have plugs that are known to work well for CL.

Lauri Malila · « **Reply #7 on:** October 28, 2015, 02:57:31 PM »

With our long stroke engine, I have found out that the biggest mistake in preparation before start is to let the engine heat up in sunshine. But my engine is side mounted, the cooling fins absorb heat quite effectively. I have measured about 50..60C cylinder temperatures on a sunny summerday.
Prime evaporates and expands quite aggressively inside a warm engine, pushes oxygen away and the engine won't start. Emergency cure is to suck some fresh air through engine by sucking from exhaust header. But I try to avoid it as oil and fuel fumes taste like @#$%. I rather solve problems by wrapping models nose in a wet cloth when weather is sunny.
I don't use nitro but I usually beef up the priming fuel with 5% of it. I've found that 10% is too much, it sometimes kicks the prop loose (I use pusher prop but a normal right hand threaded prop mounting bolt). I put prime 0,5ml on a warm day and 1,0ml when it's colder. 10 fast flicks to spread the prime inside the engine and then it usually starts at 1st flick. L

Tim Wescott · « **Reply #8 on:** October 28, 2015, 03:04:05 PM »

Quote from: Lauri Malila on October 28, 2015, 02:57:31 PM

10 fast flicks to spread the prime inside the engine and then it usually starts at 1st flick. L

Well, yes, but you're friends with the guy who builds your engines!

Lauri Malila · « **Reply #9 on:** October 28, 2015, 03:13:08 PM »

Well actually it's me who makes the most important parts. I have no cnc or spark erosion so Robbie helps with carters and pistons. But the latest version is more or less my design.
But it has nothing to do with starting:) (well it does actually, looking at tolerances and used materials)
L

Steve Helmick · « **Reply #10 on:** October 28, 2015, 03:45:14 PM »

The glowplug depth (piston to glowplug distance with piston at TDC) seems to have a lot to do with easy starting and also glowplug life. Deeper is harder to start but also better for glowplug life, from my experience. In some emails with GMA, I mentioned this finding and he agreed. I suspect this is also why RO-Jett makes button heads and various compression inserts instead of the old standby head shim approach.

If I was designing a cylinder head, I'd start by measuring the glowplug depth of various engines that were known to start very easily. I'd like to know if this dimension would be the same for a range of displacements, such as 5cc to 10cc.

Steve

Gerald Arana · « **Reply #11 on:** October 28, 2015, 04:07:23 PM »

Quote from: Lauri Malila on October 28, 2015, 02:57:31 PM

With our long stroke engine, I have found out that the biggest mistake in preparation before start is to let the engine heat up in sunshine. But my engine is side mounted, the cooling fins absorb heat quite effectively. I have measured about 50..60C temperatures on a sunny summerday.
Prime evaporates and expands quite aggressively inside a warm engine, pushes oxygen away and the engine won't start. Emergency cure is to suck some fresh air through engine by sucking from exhaust header. But I try to avoid it as oil and fuel fumes taste like @#$%. I rather solve problems by wrapping models nose in a wet cloth when weather is sunny.
I don't use nitro but I usually beef up the priming fuel with 5% of it. I've found that 10% is too much, it sometimes kicks the prop loose (I use pusher prop but a normal right hand threaded prop mounting bolt). I put prime 0,5ml on a warm day and 1,0ml when it's colder. 10 fast flicks to spread the prime inside the engine and then it usually starts at 1st flick. L

Lauri,

Be extremely careful flipping the prop in "HOT" weather. (I assume 50-60 C is hot) I did this with my Enya 7033 at a contest in Woodland and it started without the battery! Scared the 'L out of me. Luckily I didn't get my finger caught in the prop.

Cheers, Jerry

Lauri Malila · « **Reply #12 on:** October 28, 2015, 05:09:04 PM »

Quote from: Steve Helmick on October 28, 2015, 03:45:14 PM

The glowplug depth (piston to glowplug distance with piston at TDC) seems to have a lot to do with easy starting and also glowplug life. Deeper is harder to start but also better for glowplug life, from my experience. In some emails with GMA, I mentioned this finding and he agreed. I suspect this is also why RO-Jett makes button heads and various compression inserts instead of the old standby head shim approach.

If I was designing a cylinder head, I'd start by measuring the glowplug depth of various engines that were known to start very easily. I'd like to know if this dimension would be the same for a range of displacements, such as 5cc to 10cc. Steve

Yes but the depth is a function of compression ratio, there is not very big freedom of choise if you want to keep the head geometry good. I mean squish area and such.
I'd rather say that it is a sign of inefficient scavenging if fuel does not reach the plug.
The situation looks more worrying with long stroke engines, the combustion chamber needs to be quite deep for the desired head volume. But actually an ideal shape is deeper, closer to half ball or some kind of a parabola.

Bill Johnson · « **Reply #13 on:** October 28, 2015, 08:55:07 PM »

Quote from: Lauri Malila on Today at 02:57:31 PM

10 fast flicks to spread the prime inside the engine and then it usually starts at 1st flick. L

Quote from: Tim Wescott on October 28, 2015, 03:04:05 PM

Well, yes, but you're friends with the guy who builds your engines!

Back in March or so, Ty Marcucci told me about the same thing. Actually, he said 7 to 10 depending on the engine. It seems work on the 10 or so engines I've run this year, as long as they're cold. Prime for 3 prop rotations, flip the prop 10 times, attach glow driver, rotate prop and if it "bumps", ready to go. Otherwise it's probably flooded so reflip another 10, attach glow driver....

Steve Helmick · « **Reply #14 on:** October 29, 2015, 07:23:06 PM »

Quote from: Lauri Malila on October 28, 2015, 05:09:04 PM

Yes but the depth is a function of compression ratio, there is not very big freedom of choise if you want to keep the head geometry good. I mean squish area and such.
I'd rather say that it is a sign of inefficient scavenging if fuel does not reach the plug.
The situation looks more worrying with long stroke engines, the combustion chamber needs to be quite deep for the desired head volume. But actually an ideal shape is deeper, closer to half ball or some kind of a parabola.

Theorists would say there's an optimal shape, but I've found CR and glowplug depth more important than shape. The squishband is more important for straight alcohol (or petrol) based fuel. Nitro increases heat, but doesn't really light afire all that easily. Eighty percent (80%) Nitro is real difficult to fire up.

If your engine is flooded, flip the propeller backwards about 10 times to pump out excess without bringing in more.

Steve

frank mccune · « **Reply #15 on:** October 30, 2015, 09:52:55 AM »

Hello:

I will go out on a limb and make a general statement! The more an engine costs, the easier it is to start!

I have put on my flame retardant suit, Lol

Frank McCune

Lauri Malila · « **Reply #16 on:** October 31, 2015, 02:19:46 PM »

Quote from: Steve Helmick on October 29, 2015, 07:23:06 PM

Theorists would say there's an optimal shape, but I've found CR and glowplug depth more important than shape. The squishband is more important for straight alcohol (or petrol) based fuel. Nitro increases heat...

..and practical tests will prove it correct.
Maybe it's a cultural thing but I rather use 2,8oz per flight than the 7..8 that seems to be the norm here.
L

Ken Burdick · « **Reply #17 on:** November 01, 2015, 04:33:00 PM »

Pat Willcox shared (years ago) about how to start a flooded VA .049....
1. disassemble the engine
2. wipe all parts dry
3. reassemble and start.

Chris Wilson · « **Reply #18 on:** November 02, 2015, 01:29:35 AM »

Quote from: Lauri Malila on October 28, 2015, 02:57:31 PM

10 fast flicks to spread the prime inside the engine and then it usually starts at 1st flick. L

Wouldnt that be an eleventh flick start?

But seriously, surely a good piston liner fit and a minimal prime with a sharp flick of the wrist is all that is required.

Anyone try ether in a glow engine on prime? No need for a glow plug.

Author Topic: What makes an engine easy to start? (Read 4441 times)

frank mccune

What makes an engine easy to start?

dennis lipsett

Re: What makes an engine easy to start?

Dan McEntee

Re: What makes an engine easy to start?

Air Ministry .

Re: What makes an engine easy to start?

frank mccune

Re: What makes an engine easy to start?

Brett Buck

Re: What makes an engine easy to start?

Tim Wescott

Re: What makes an engine easy to start?

Lauri Malila

Re: What makes an engine easy to start?

Tim Wescott

Re: What makes an engine easy to start?

Lauri Malila

Re: What makes an engine easy to start?

Steve Helmick

Re: What makes an engine easy to start?

Gerald Arana

Re: What makes an engine easy to start?

Lauri Malila

Re: What makes an engine easy to start?

Bill Johnson

Re: What makes an engine easy to start?

Steve Helmick

Re: What makes an engine easy to start?

frank mccune

Re: What makes an engine easy to start?

Lauri Malila

Re: What makes an engine easy to start?

Ken Burdick

Re: What makes an engine easy to start?

Chris Wilson

Re: What makes an engine easy to start?