Primer -fitting to manifold

[simatos]

Again not clear to me from the IPC. At the point where the primer line attaches to the manifold is there a specific fitting or injector used on the o-300 engines. I have one fellow here on the field who used a pipe fitting and it has worked for years. Can you help me with the correct part Thanks G

[Bruce Fenstermacher]

The primer line gets attached to a fitting like an AN822 which is a 90 degree fitting with pipe threads on one side and flared tube on the other.

The fitting goes in the hole in the manifold near the oil sump on the left side (pilot side). The hole in the other manifold gets plugged or you could attach a manifold vacuum gage there,

[Tom Downey]

It is a special fitting, it has the typical Bulbed line fitting as all Primer lines have.

It's part number is AN4002-1 see figure 34 item 27 in the IPB It amounts to a #60 drilled oriface in a brass fitting that forces a spray into the manifold.

[simatos]

guys thanks very much. This has not turned up in the goodie box so I will call spruce in the morning Cheers g

[davevramp]

Does any one know why the primer injects in to the manifold rather than on top of the intake valve?

[GAHorn]

Simplicity. Injection/priming over the intake valve requires multiple lines to feed multiple cylinders. (And by the time a manual primer fills all the lines so that all cyls get primed...the cyls closest to the primer are over-primed...causing loss of lubrication to the intake valve ...and flooded induction manifolds which is a fire hazard.
By using a single primer injection point down lower in the induction spyder, multiple cyls are fed more equal amounts of fuel, and less fuel is required to prime multiple cylinders...intended to reduce the fire hazard.

[simatos]

In the AN fittings section in Spruce, for Primer fittings, I see the primer discharge niple AN4022-1. There are other associated items they list and I want to get everything for the complete install.
I will need the nut AN 805-2 I expect.
There is also the union cone AN800-2. Is this the little bulb that compresses between the nipple and the nut.
Finally they list an elbo AN4023-1 tho you have suggested above an AN 822 would also work. This is the last connection for the engine and i would like to get all the goodies for the primer hook up. Thank you guys all again. I just never realized how many thousands of parts go into one of these machines G

[blueldr]

I used to have a helluva time getting a decent start on cold mornings up in Idaho so I installed a primer manifold on th top of the engine with equal length lines to each cylinder feeding regular primer nozzles at each intake port. It made a world of difference. The engine starts smoothly on all cylinders rather than raggedly shaking until the left bank started getting fuel. It was a good modification and , no, I did not ask for or get any permission fromthe fuzz.