Front oil gallery port?

Aero Sport has a document that describes a pre-lubrication procedure for first engine run or for starting after an extended period of not running. One procedure involves taking out the bottom plugs, disconnecting the mags, and turning the starter over until you have oil pressure. The other method, which they label the "preferred method" involves forcing warmed oil in through "a front oil gallery port". The O-320 operating manual does not have a diagram identifying this "front oil gallery port". Can anybody show me where this is?

Look at the lubrication system diagram. There are two allen plugs up front.

Ok thanks. The Aero Sport document says to use forced air to force the oil through. A youtube video shows them using an electric oil pump. Has anyone done this with a hand oil pump?

II would think a hand pump would be better than air, I wouldn't want to pump air into the system but a electric pump would be best. Maybe a cheap car fuel pump?
If you prelubed the bearings during build I personally would not be very concerned about it. The oil pump will supply pressure very quickly. I would do the no plug, mags off method.
When we started DC-10s the oil pressure would take forever to come up, well after light off.

See Lycoming Service Instruction 1241C.

If the engine has substantial time on it, I'd be very leery of removing a front oil gallery plug. The galleries dead-end at the front and could collect lead-based crud against the pipe plugs which then could be broken loose and pumped into the bearings and hydraulic valve lifters (tappets) if you unscrew one of those plugs and inject oil there.

A better location to pump oil into would be to rig a temporary Tee into one of the oil cooler lines. That's what I did before first start of my overhauled engine. The vessel I used was a 2-gal paint pressure pot with new fluid hose which worked well.

Regardless, the best course of action is to follow SI 1241C.

Ok thanks guys. Perhaps i will just use the method described in the SI 1241C.
Also, I'm installing a new oil cooler - would you recommend lying hte oil cooler on it's side and pre-fillign it with oil and attaching the hoses before mounting it to the rear baffle, to get as much oil in the system as possible before start?

When i overhauled my O-320D2A Narrow deck engine. I used the assembly lubricants listed in the Lycoming overhaul manual, had all accessories, oil cooler looped around, baffle's installed, just ready to put back on airframe. Sump filled with 6 quarts W100, mechanical oil pressure gauge connected to oil pressure port, and as the video shows it took 4 seconds of starter cranking to get 50 PSI. I did not pack the oil pump. Thats starter RPM with no plugs installed. I would send the video to anyone that wants to see it.

Keith Rhea
RV7
2023 Donation