I am converting to a 6 cyl. I have a 2.2e case. I purchased a PMS tank. I have been able to figure out the normal routing for the oil lines however I already had an oil cooler in the front of my car from my previous engine. I was using a Mocal Sandwich plate. Here are my questions-

1. I plan on using non-stock oil lines- what size should I use? I already have 10an for my front oil cooler- is 10AN adequate.

2. Is there a way that I can use my Mocal sandwich plate? If not- which type of thermostat should I get? At what level should it open (I think my current is 180 degrees)?

3. Where does the line from the vent hose on the oil filler neck connect? Does it connect to the vent on the center/top of the case?

You need an12 on a -6.
Including the front cooler

I'm glad I posted this. I am not sure why I thought I had 10an- I just checked and I have 12AN.

You need a mocal thermostat.
-10 might work for a 2.2, but -12 would be the correct size. I see you have -12 so you are good.
How big is the cooler? That can be a restriction itself if it's just a mesa style.

Post pics

I can't remember, I think the one on the tank goes the top of the case and the one on the neck goes to an air filter/carb or a better system is to an catch can then the air filter.

That is the correct hook up of the tank / engine vent lines.

I have run three conversions without a thermostat to control oil to the front cooler. No problems.

I have an RX7 cooler upfront with 12an lines.

I have carbs- I don't see an area where I can put a return line. I wouldn't mind getting a catch can but still I don't know where to run the return line.

Does the RX7 cooler still have it's thermostat and small ports or has been modified for -12 lines?

Do you have the single box intake? There should be a port/nipple on it somewhere.

My cooler has been modified for -12 lines. It does not have a thermostat.

I have the dual K&N water shield type filters.

The K&N's have a hole on the side of the rainhat and you put a fitting in the hole. The fitting doesn't have to go through the filter, the carbs suck the oil vapour in and burn it.
A catch can is a good idea as it collects any drippy oil and then only vapour is going to the carb. If the catch can is filling up too fast run a bit lower oil level in the tank. You could also run a drain back to the case if you don't want to empty the catch can.

Some guys run a catch can with only a cheap breather on it, but I feel the just makes a mess of the engine bay.

Can I just run the vent hose from the filler neck to a catch can and skip the output from the catch can to the carbs?

You still have to vent the catch can, an oil vapour comes out. I really don't like the mess it makes of the bay.
You could run a vent down under the engine.

Venting to the carbs to be burnt up is more environmentally friendly.

The 911 race car guys like to run lines that are as large as possible--any chance of a drop in oil pressure is one chance too many for them. They often will go with -16 or even larger for cooler and pump lines. I'm thinking that -12 should be regarded as a minimum in this case.

Don't use the sandwich adapter. I'm pretty sure the inlet and outlet ports in it are the equivalent to -8 size, for one. The 911 and 914-6 oil line routing has already been worked out a zillion times; follow the factory for a good solution. A 180F thermostat is just fine for just about any oil-cooling setup in our cars.

With no t-stat, I'd be a bit worried about how long it took things to come up to temp, but you can keep track of that with a gauge. If you find you're never getting to 180F, that's a real problem. If you're only getting to 180F for a few minutes each drive, that's still a problem. At that temp, it takes some time for water to out-gas from the oil.

--DD

-12AN is fine but running -16AN from tank to engine doesn't hurt since it's gravity fed.