Any reason to keep my primer system?
- Thread starter Zaylor
- Start date
cubdriver2
FRIEND
upstate NY
Couple reasons, when it's cold here even though my engine is plugged in and warm I need to leave the primer out about 3/8" to act as a choke for the first 20 or 30 seconds to keep it running.
Reason 2 is if your hose from your gascolator get blocked or your carb has a flow restriction you can pump yourself home or at least to a more friendlier area.
Reason 3 is if you foolishly run out of gas or enough fuel head pressure while over woods you might but be able to pump another mile or two and make it to an airport. Don't ask why I know this
Glenn
Reason 2 is if your hose from your gascolator get blocked or your carb has a flow restriction you can pump yourself home or at least to a more friendlier area.
Reason 3 is if you foolishly run out of gas or enough fuel head pressure while over woods you might but be able to pump another mile or two and make it to an airport. Don't ask why I know this
Glenn
BC12D-4-85
SPONSOR
Fairbanks, AK.
Prime the cylinders not the induction spider. If the intake tract is cold most of the fuel will turn to liquid and then run down and out of the carb. Most cylinders have a drilled and tapped 1/8 NPT hole on the top over the intake valve for a special restricted primer fitting (AN4022-1). That fitting vaporizes the fuel better than a plain hole and prevents excessive air intake/lean running if the primer line breaks.
Four cylinders primed is better than one. If you want to use the accelerator pump give it a few pumps then quickly pull or crank the engine through several prop turns to get fumes to the cylinders. Again, top priming next to the intake valve is better.
But like Glen notes some of us have had to depend on a primer to act as a choke or keep the fires burning when the carb fuel bowl is empty or restricted.
Gary
Four cylinders primed is better than one. If you want to use the accelerator pump give it a few pumps then quickly pull or crank the engine through several prop turns to get fumes to the cylinders. Again, top priming next to the intake valve is better.
But like Glen notes some of us have had to depend on a primer to act as a choke or keep the fires burning when the carb fuel bowl is empty or restricted.
Gary
Bill Rusk
BENEFACTOR
Sandpoint, Idaho
I have no primer and it works fine. Get the engine turning over, then pump the throttle a couple of times and it lights off. The only disadvantage is there is not much way to prime the engine if you have to hand prop it. Different strokes for different folks. Do what ever works for you.
Bill
Bill
aktango58
FRIEND
18AA
It should prime to the cylinder heads, not the carb.
Though Bill gets away without it so far, I have had plenty of times I needed the primer to get started.
As an example, we were ferrying a 172 north one time with a two cylinder primer. It would not start! We did everything, then finally got some stove pipe and ran heat into the engine compartment, (just frosty on the ground- not really cold). the owner installed a 4 cylinder primer once home and has never had another issue.
Though Bill gets away without it so far, I have had plenty of times I needed the primer to get started.
As an example, we were ferrying a 172 north one time with a two cylinder primer. It would not start! We did everything, then finally got some stove pipe and ran heat into the engine compartment, (just frosty on the ground- not really cold). the owner installed a 4 cylinder primer once home and has never had another issue.
mvivion
SPONSOR
Bozeman,MT
Just make dang sure that engine is turning over before you use the accelerator pump. I’ve seen one airplane burned to the ground by someone trying to start with the accelerator pump.
i MUCH prefer a primer system and USE IT to start. If you have fuel injection, how you going to prime that engine to prop it?
As George said, put the fuel in the cylinder, not the lower induction. One little back fire can ruin your day. Doesn’t happen often, but it’s really bad when it does.
MTV
Carey Gray
Registered User
Thun Field, Washington
I don't have a primer in my Cub and no starter. Has worked fine for about 25 years once I got the sequence down.
I have an IO360 and a wobble pump in my Pitts. I never use the wobble pump.
I pull it through 12 blades with the mixture rich, it starts building fuel pressure at about 8-9 blades. Go mixture lean and it holds fuel pressure until I'm ready to start and it starts on the second blade, like clockwork.
As a wise man once said "Different strokes for different folks".
I have an IO360 and a wobble pump in my Pitts. I never use the wobble pump.
I pull it through 12 blades with the mixture rich, it starts building fuel pressure at about 8-9 blades. Go mixture lean and it holds fuel pressure until I'm ready to start and it starts on the second blade, like clockwork.
As a wise man once said "Different strokes for different folks".
fancypants
FOUNDER
IL
Those of you that are priming your small Continentals directly at the cylinder head, which cylinder are you plumbing your primer to? Just one or all four?
I might be forgetting, but I can't recall ever seeing any C90's or O-200's with primer lines running up on top of the cylinders. Pretty sure some cylinder castings aren't even threaded for the primer nozzle.
I might be forgetting, but I can't recall ever seeing any C90's or O-200's with primer lines running up on top of the cylinders. Pretty sure some cylinder castings aren't even threaded for the primer nozzle.
How's that work? Or do you mean you give it a little pump during the first 30 seconds to keep it running. I have experienced that in the cold.
I always wondered why primers were generally not filtered by the gascolator, but this wouldn't work if it was.
Reason 3 is if you foolishly run out of gas or enough fuel head pressure while over woods you might but be able to pump another mile or two and make it to an airport. Don't ask why I know this
Glenn
Well those are enough reasons for me!
People preheat a lot better now than they used to. I'd tell you if you need primer to keep it running you need better preheat practices but that said, I used to use primer regularly to keep it lit when cold starting. No amount of throttle jockeying will keep a really cold engine running. Reiff pretty much solved that problem.
Yeah, that's why the baby Continental primer system is kind of a joke. As Fancypants said, there's no option for cylinder prime, to my knowledge. So the primer puts fuel in a difficult to atomize and dangerous spot.
I would also like to inquire as to where Zaylor operates from?
I flew Conn. winters allot.
When I had my C-150 I recall pre heating it a time or two. I generally just fired it up cold.
I did however richen and lean the idle mixture seasonally.
I flew Conn. winters allot.
When I had my C-150 I recall pre heating it a time or two. I generally just fired it up cold.
I did however richen and lean the idle mixture seasonally.
mvivion
SPONSOR
Bozeman,MT
Out of curiosity, what is you sequence to start your cub?
I also have no starter or primer. Three shots of throttle and the third blade it usually starts. If it’s very cold, it might take a min.....Pierce, txpacer and BTV witnessed my cold weather workout routine.
Carey Gray
Registered User
Thun Field, Washington
Cold, I give it a couple of pumps on the throttle and pull it through about a dozen blades, one shot of throttle and it'll start on the third blade. Warm, I give it one shot of throttle and it'll start on the third blade. I always start the engine with the mixture at idle cutoff. It'll run for a few seconds which is long enough to make sure everything is OK. When I'm sure my head is not planted where it shouldn't be, the mixture goes in.
In my opinion, the propeller is there to pull the airplane forward and to kill you if you're not careful.
Alaska. I preheat when needed. It's not that I have any trouble starting the plane. I just thought the primer was silly considering the location.
BC12D-4-85
SPONSOR
Fairbanks, AK.
If you remove the primer from the induction spider it offers the opportunity to install a manifold pressure gauge to that fitting. Small Continentals are prone to carb ice and a MP gauge will drop off if ice forms faster than rpms.
Threaded primer plugs with square heads above intake valve:
Attachments
cubdriver2
FRIEND
upstate NY
The Clipper we were flying skis with today had a carb.problem last time out and quit running, he pumped it back to a safe landing
Glenn
Glenn
aktango58
FRIEND
18AA
Glenn, respectfully, have you considered flying a plane that the engine does not quit while airborne?;-)8)8)8)
Seriously, I might not have thought about the primer for that- great learning.
Having the primer is another tool in the tool box. That one time you are out, and get yourself into a spot longer and the plane cools a bit more than planned, it is going to get dark and your choice is to be stuck for DAYS inside a tent in the storm or start it now and get gone... best to have it and not need it.
Only my opinion.
BC12D-4-85
SPONSOR
Fairbanks, AK.
My first engine out involved trying the primer - O-360 PA-12 - it would keep the prop spinning but not enough to maintain altitude. Two point primer with throttle cracked some, however a four point would have been better. Try it sometime. When cracked but not pumped it'll run rich and rough (not rare, unlike the whisky). Who hasn't forgot to lock the primer at least once?
Gary
Gary
I'm surprised that hand prop guys aren't the biggest advocates FOR 4 cylinder priming. It makes starting so much easier. That's no different for key starting. I always want my plane to fire as quickly as possible. A primer system has a clear advantage for that. The colder the engine the bigger the advantage.
I know a very seasoned old pilot that told a story about a power loss in flight. He figured out he had carb water problems and used the primer to feed clean fuel into the cylinders so he could make it to a strip.
I know a very seasoned old pilot that told a story about a power loss in flight. He figured out he had carb water problems and used the primer to feed clean fuel into the cylinders so he could make it to a strip.
Steve Pierce
BENEFACTOR
Graham, TX
What engine? The staock carb on the O-235 on the Clipper didn't have an accelerator pump.
cubdriver2
FRIEND
upstate NY
Yup, I asked him today and that's what it's got. Must be lite, it performs very well
Glenn
Tried your idle cutoff start procedure today. Works just as you say. Thanks again
cubdriver2
FRIEND
upstate NY
I bet if you give it 2 pumps of the throttle and go Hot it will start on the third blade
Glenn
BC12D-4-85
SPONSOR
Fairbanks, AK.
Another tip is to prime sequential cylinders in order of firing if priming less than four. That way you get two burns in a row to get things turning.
Gary
Gary
Carey Gray
Registered User
Thun Field, Washington
It would start, but I kinda like making sure there's compression and all the cylinders feel even. At least on the first start of the day.
