My O-320 powered PA-22 was last rebuilt sans fuel primer. A couple pumps of the throttle was always enough to get it started...but that was in the moderate temps of Oregon.

Either through my ham fistedness or lack of experience in cold weather starting, there was a time when I could not start it easily with just accelerator pump. Now, I live in Minnesota with cold temps that make Oregon look tropical.

Ideally, I'd be preheating adequately which makes cold starts far easier, but should I add a primer system?

The problem is that getting enough start fuel with the accelerator pump also gets enough start fuel in the carb to start a fire there. Secondly, when caught out in the cold there is a fair chance of running the older battery system down. New 24 volt would be different I expect. On pipeline I always tried to get inside for the night, but was caught out a bit. Primer made starting no big problem. I flew both 150 hp and 160 hp 0-320s. I flew O-540 Pawnee without primer and starting in cold weather required a lot of accelerator pumping.

O-320s want a lot of fuel to start and then want to idle and run lean. They start well with just accelerator pump when it is not cold.

Install a primer. No question. Contact summed it up quite well. Easy to start a carb air box fire using the accelerator pump.

And, yes, I know it’s been done many times, but…..

My RULE with using accelerator pump on starts (Lycoming 320/360) is this: Only use accelerator pump (rapid fore and aft movement of throttle) for HOT starts, and ONLY WHILE CRANKING WITH STARTER. That way, hopefully, the engine will suck any air box fire into the cylinders, where fire belongs. I very rarely use the accelerator pump even on a hot engine. Crack the throttle a half inch (and the amount of throttle opening varies a bit, but don’t open it much) and crank. If set up right, it’ll start hot every time. When hot, it’s REALLY easy to flood these engines.

Now, consider how you’re going to hand prop that engine when your battery or starter lets you down and it’s -30. The simple answer is……use the primer.

Especially in cold country, I ALWAYS want a primer. The 185/206s I flew had primers, which was an option. Some of our planes had been to 90 North. No place to be without a primer. Again, no way to hand prop one of these without the electric fuel pump…..if no primer.

Frankly, it’s too easy to get complacent, especially in lower 48. But MN can be “brisk”.

MTV

Yes, you should.

Yes for all the reasons posted. DENNY

A definite yes. Safer due to fire hazards and out in the cold no starts as well as easier (as in money and time saving) on the battery and starter. And last but certainly not least, avoiding possible domestic issues from all of the above!!!

Message received. Thanks everyone.

FWIW I only put primer lines to the back two cylinders on our O-320-B2B and after 3 winters of use it cranks up just fine either hand prop or starter. Saw a few cubs primer plumbed that way and the owners seemed to have no issues plus it made the whole system simple without the front two lines. Seems to start just as fast on a cold day as the other planes that have 4 lines. Just my .05 cent.

TVATIVAK71 wrote:FWIW I only put primer lines to the back two cylinders on our O-320-B2B and after 3 winters of use it cranks up just fine either hand prop or starter. Saw a few cubs primer plumbed that way and the owners seemed to have no issues plus it made the whole system simple without the front two lines. Seems to start just as fast on a cold day as the other planes that have 4 lines. Just my .05 cent.

We've only got 2 cylinders primed on the O470 in the 180. It's a bit temperamental when cold but with the right words and just the right squint it'll catch and pull through the carb to run on all 6. If I didn't have a heated hangar I might get more excited to add cylinders to the primer circuit but it works - I also wouldn't hesitate to go with just 2 on a 320 if it's a clean install. I've got no cents so my advice is worth what you paid.

DreadPirateWill wrote:We've only got 2 cylinders primed on the O470 in the 180. It's a bit temperamental when cold but with the right words and just the right squint it'll catch and pull through the carb to run on all 6. .....

Ditto on the 470K engine in my 53 180.
I don't think it can possibly work as well as a 6-cylinder priming system,
but it doesn't get very cold here so it suffices.
I plan to change it at overhaul time,
I've already got the "spider" aka primer distributor block.

Halestorm wrote:Yes, you should.

I always appreciate your brevity Sam

AEROPOD wrote:

Halestorm wrote:Yes, you should.

I always appreciate your brevity Sam

Was hoping for a 20 minute Youtube video explaining the history of aircraft engines and carburetors.

Zzz wrote:

AEROPOD wrote:

Halestorm wrote:Yes, you should.

I always appreciate your brevity Sam

Was hoping for a 20 minute Youtube video explaining the history of aircraft engines and carburetors.

Was that a slam on someone’s post being long winded to your response? The maybe I need to go back and change my response to “yes on primer”. Just asking..

TVATIVAK71 wrote:

Zzz wrote:
Was hoping for a 20 minute Youtube video explaining the history of aircraft engines and carburetors.

Was that a slam on someone’s post being long winded to your response? The maybe I need to go back and change my response to “yes on primer”. Just asking..

LOL, no, not at all. I appreciated your response. It was a swipe at modern Youtube how-to videos. You know how when you're looking for a quick answer to something and the video you find has 15 minutes of lead-up on the topic? As if you had no idea why you're asking your question and need the background? I think they do that for greater monetization.

Put a Surefly magneto on and set it up with variable timeing.

Zzz wrote:

TVATIVAK71 wrote:

Zzz wrote:
Was hoping for a 20 minute Youtube video explaining the history of aircraft engines and carburetors.

Was that a slam on someone’s post being long winded to your response? The maybe I need to go back and change my response to “yes on primer”. Just asking..

LOL, no, not at all. I appreciated your response. It was a swipe at modern Youtube how-to videos. You know how when you're looking for a quick answer to something and the video you find has 15 minutes of lead-up on the topic? As if you had no idea why you're asking your question and need the background? I think they do that for greater monetization.

Kinda like in certain “special videos” filler in the front and gotta fast forward to get to the good stuff. But seriously…..get a primer. LMAO!

TVATIVAK71 wrote:
Kinda like in certain “special videos” filler in the front and gotta fast forward to get to the good stuff. But seriously…..get a primer. LMAO!

LOL you took it there. I like you.

Is there any strategy about where on the panel to locate the primer pump?

In my panel design I just shoehorned it in on the far left side because it kinda keeps it out of the way. Its only used at startup, not like a carb heat control where you might coordinate it with throttle in various phases of flight. Does this thinking jive with the collective?

I’ve probably flown 20 different aircraft with primers and all were in the lower left somewhere. Seems like the right place.

Depends on where your starter is. YMMV, but on the occasional cold morning with a cranky engine I've found need to pump primer while starting to keep it running on primed cylinders till it pulls fuel through the carb. Feels safer than relying on accelerator pump via throttle.
So - make sure you can have one hand on starter button/key and other on primer. On our 180, starter button on left so primer bottom middle of panel.