Manifold pressure and Primers O-360

[Planecrazy232]

I have a primer setup on my engine with fittings in the normal ports where the manifold pressure would be picked up. How do I go about hooking up manifold pressure. Do I just tee it into one of these fittings or is there another place to pick up MP?

Anthony

 

[Raymo]

Most engines have primers in only 2 or 3 ports. My 66 Cherokee 140 only had two primer ports (2 and 4) and started easily. The typical 3 cylinder primer setup leaves the #3 cylinder port available for MP. If your setup has primers in all ports, disconnect one and use it for MP.

 

[az_gila]

Two obvious options -

The are two port locations on each cylinder, use the second one for MP.

or,

Only prime 3 cylinders and use the easily accessible port for your MP pick off.


Second option is easiest.

 

[Planecrazy232]

I didn't know there were two ports. I'll look at that tonight. Blocking one primer is easy too. Both are very viable options. Thank you!!!

 

[AX-O]

The are two port locations on each cylinder

All cylinders are not created equal. Some only have one port, like my old ones (O-320 B2B).

Break

Like others have said, you dont need to prime all the cylinders. My old plane had a primer line on only two cylinders and it worked just fine.

 

[Raymo]

I didn't know there were two ports. I'll look at that tonight. Blocking one primer is easy too. Both are very viable options. Thank you!!!

The lower port is typically used for primer nozzles on carbureted engines and is easily accessible outside the baffling. The #3 cylinder port is closest to the firewall for the shortest line run.

The upper port is typically used for injector nozzles and is inside the baffling. Hence, az_gila's suggestion that option 2 is easier.