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Fuel primer pipe support

J

jrm7997

Active Member
I’m having trouble finding out how to support my primer pipes. I’m in the process of doing a top overhaul. As we put the engine back together I need to support the four primer pipes. 1/8” copper tubing routed along the push rod tubes.

The original builder used a semi soft grey material. It’s retained its flexability but isn’t soft. It was used to hold onto the tubes (stop vibration) and keep them approximately 1/8” off the push rod tubes.

I’m thinking about using

Loctite 37467 Black RTV 598 High Performance Silicone.​


Any suggestion, thoughts, advice????

Thanks in advance
 
Lycoming service bulletin #342G shows how injector lines are to be supported from the push rod tubes. You could use the same p-clamp method for your primer lines.
 
RV7 To Go said:
Lycoming service bulletin #342G shows how injector lines are to be supported from the push rod tubes. You could use the same p-clamp method for your primer lines.
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I’m just going to look it up the SB right now. I’m pretty sure I’ve seen this in a photo search I did.

Thanks.
 
Humm. This is about fuel lines for injected engines. I’m looking for info in the primer lines on a carbureted (although I’d expect it to be the same on an injected) engine.

I think the adel clamps are the second method.


anyone use RTV.
 
Hmmm…not sure why folks are talking about pushrod tubes for primer lines - most of the ones I’ve seen in all my years with Lycs are on teh “bottom” of the cylinder heads, and are clamped along with spark plug wires to Adel clamps on the rocker box cover screws.
 
Well mine is definitely different. See pics. On the primer tubes (PT) there are plastic tubes that were slid over the pipe before making. Each of those had a grey substance under them. Obviously to stop vibration.

My plan was to use black RTV under the rubber tubing. Second option is adel clamps.
 

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jrm7997 said:
Well mine is definitely different. See pics. On the primer tubes (PT) there are plastic tubes that were slid over the pipe before making. Each of those had a grey substance under them. Obviously to stop vibration.

My plan was to use black RTV under the rubber tubing. Second option is adel clamps.
Click to expand...
Well that’s….interesting! Looks like they used the fuel injection ports int eh cylinders for the primer. It certainly looks like a serious and rugged system, including that divider on the spine. I guess they do I things differently in Canada! 😉

Honestly - not sure I see anything wrong with it if it works well - just like nothing I’ve ever seen before.
 
Ironflight said:
Well that’s….interesting! Looks like they used the fuel injection ports int eh cylinders for the primer. It certainly looks like a serious and rugged system, including that divider on the spine. I guess they do I things differently in Canada! 😉

Honestly - not sure I see anything wrong with it if it works well - just like nothing I’ve ever seen before.
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Actually, i think the difference here is your 0-360 and my 0-320 (160HP). When putting the rebuilt cylinders on one pushrod was too short so we dug around the airport for different ones. All we found were for a 0-360 and all too long :)

Talking to my mechanic this morning he said all the 320s, as far as he knew injected into the top like mine.
 
jrm7997 said:
Actually, i think the difference here is your 0-360 and my 0-320 (160HP). When putting the rebuilt cylinders on one pushrod was too short so we dug around the airport for different ones. All we found were for a 0-360 and all too long :)

Talking to my mechanic this morning he said all the 320s, as far as he knew injected into the top like mine.
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That's not been my experience. The 320's I have seen with primers have all been below. The 160 hp 320 I purchased had the primer lines underneath where they have a habit of cracking over time. I removed them and just used the accelerator pump for priming. Yours is the first I have seen using the injector ports. As was said, looks robust and much better support the way it is. High temp RTV should be fine.
 
jrm7997 said:
Actually, i think the difference here is your 0-360 and my 0-320 (160HP). When putting the rebuilt cylinders on one pushrod was too short so we dug around the airport for different ones. All we found were for a 0-360 and all too long :)

Talking to my mechanic this morning he said all the 320s, as far as he knew injected into the top like mine.
Click to expand...
Strange. I’ve owned a couple of O-320’s in my life, and they all had the primers on the bottom, like the Lycoming manual shows. But again - yours looks robust to me - if it works, I wouldn’t change it (experimental, you know!).
 
I have never seen primer lines on top either, and I'm an APIA that has seen alot! Only downside is that leaks run fuel on the engine, if below, it goes down into cowling. But the lines are there, and they work. I am not an advocate of sticking things together with silicone, and it always looks messy, plus, you cant "disconnect it" for repair/replace. See how I attached my plug wires to the pushrod tubes..you could do similar, just spin the small clamps 180 degrees from my orientation.
 

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different ways to skin that cat :)
In the process of exchanging my engine, this what it looked like... the right side nipple being closer to the firewall where my e-valve is located, the routing is short and direct. The left side (excuse the truncated picture) a bit more meandering, held by small size Adels.



1.jpg
2.jpg
 
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