Is the vacum tube that comes out from the base plate under the choke for distributor vacum? Also were are you guys getting pcv vacum when you use this carb? This engine came originally with a down draft tube so I don't have the spacer with vacum port.

There was usually a distribution block with a big port on #4 runner, and some had two wirh another on the front on #5 for manifold sources. These aren't optimal for PCV though, they work for power brakes, vaccum modulator etc... they do fine. A spacer with a large vacuum nipple on the back is the best because it distributes the blow-by to both sides of the manifold and not just to one runner.

You can get a universal 4 hole aluminum spacer and make your own, Go in through the back side and drill two 1/8-3/16th inch holes on an angle to the backbarrels of the spacer that intersect in the rear of the spacer. Take a 3/8" drill and drill into that intersection about 1/3 the thickness of the spacer. Clean the intersection up with a thin dremel bit then tap the hole with a pipe tap and put a hose nipple in there. You then have a distributed vacuum source capable of running a PCV.

is just behind the r/f mounting hole in the base.

Look on ebay. There is a guy who is reproducing a Boss 302 carb spacer cut out of aluminum. It's about 3/8 thick and comes with a big pcv nipple. I've got one on the 428 in my 72 Crew Cab.

If you don't see him on ebay, look for him on the Boss302.com site.

Tim

1970 Boss 302
1972 F250 Crew Cab (powered by 66 Super Marauder 428)

I'm going to use the old hot water spacer off the original 352. It has a place that can be drilled out to get idle vacum.