DCOE - PCV - Vacuum Advance

I've got a DCOE 45 on my '74 and need some advice on attaching the PCV and vacuum advance. In the photo, the yellow arrow is the valve cover vent, which is welded shut by the PO. The red arrow is the crankcase vent. The blue arrow is the vacuum advance port on the dizzy.

It's my understanding that attaching any type of vacuum to the crankcase vent will just end up sucking oil into the intake. Should I rework the valve cover to reopen the vent tube and somehow attach a PCV and hose? If so where to on the DCOE? What should I do about the open crankcase vent? Someone told me a while ago to attach a hose to the crankcase vent and install an anti-backfire valve in the header. Another person told me not to worry about it and just put an air filter on it.

As far as the vacuum advance goes. Do I really need it? The engine runs really well from 1.5k rpm to top end. It does have some bog from 900-1k, off the line. But I don't race, and have gotten used to it. If I were to attach it then where to? Drill and tap the manifold?

Or if the everything is working fine, leave it the hell alone haha?

Thanks in advance for the advice.

Here you can see how I vented my crankcase to the air filter. You'll either need to reopen the original vent on the valve cover, or use a vented cap.

As for the vacuum advance....I run mechanical advance only since that's normal on a DCOE. My distributor (a 45D) was curved by Jeff at Advance for that application.

That off-idle bog will mostly go away if you have the distirbutor recurved so that you can run at roughly 16 BTDC at idle, then have less mechanical advance from the distirbutor in the higher rpms. I always recommend deleting the vacuum advance in DCOE cars. Since the carb is so much larger, engine vacuum is decreased and its function is skewed anyway. I tried everything I could to get a vacuum advacne to work well with a DCOE and never got it to do anything but make the engine ping. I tried several different vacuum units with varying degrees of advance, as well as ported and manifold vacuum with various tube sizes.

Vacuum advance is an economy device.
That carb is not for fuel economy,,its application is for performance..

I am doing the same with the exact set-up you have. You want to put a PCV valve back into play so that positive pressure is pulled out of the engine. If you drill and tap the boss on each manifold, you can T the two together and use a pcv valve of an enigne of similar displacement. Or you can just tap one branch and plug in the stock pcv unit connected to the tappet cover vent.

As others have said, ditch the vacum advance dizzy. Jeff will fix ya up.

Pete

Like I said in the other thread, I ran the stock pcv from an 18GB Engine branches off of only the front stem of the intake manifold. I ran this way for 20 years with no problems, there's enough suction from the front. Two cylinders to evacuate the positive pressure in the engine. I never had any trouble running this way. Granted branching the two sides of the intake together is a better way to do this, this will also help with the intake signals to the engine by branching the intakes together and equalizing the I take pulses to the cylinders.

So, if I had to do it over, I would branch them together with a T and hook the stock 18GB PCV Valve into the center of the two, this is easily acheived by drilling and tapping the bosses that are already cast into the intake mani!

B

Oh, I forgot, do away with the vacuum advance by getting either an electronic dizzy thY you can set the advance or a mechancal advance dizzy like the Mallory dual point. It is very important to have the dizzy recurves to run with the dcoe, it will remove that initial flat spot you're probably feeling now when you plant your foot from idle!

B

Thanks for all of the advice. Two more things to put on the old to-do list!

Ed