Virtually all of the original GM tripowers had at least one of the end carb bases drilled for a vacuum fitting. Most were 1/8 pipe, but Olds had a 1/4 pipe on the rear carb of the J-2 set-up. Some had both drilled. The hollow studs were quite common in the late 1950's and the 1960's. I fabricated lots of them 40 years ago before someone reproduced them. About 10 minutes on a lathe to re-purpose a bolt. As mentioned in this thread, another solution was a tapped spacer. Pontiac used these in roughly 1961~62 on the center carb of a tripower, with non-tapped spacers under the ends, thus keeping all three carbs at the same height. Pontiac also tapped both planes of a dual-plane, screwed in hose fittings, and then connected these with hoses to a fitting that looked like the letter "E" with the top "horizontal leg" removed. The top vertical was then connected to the PCV. The fitting used to be available from Ames, haven't checked recently. Generally, the original manufacturers had most of the problems we face, and came up with lots of different solutions; we just need to be aware of automotive history. Jon
I have the OG red stuff on the way. Just wanted to make sure it all fired up ok before I put it all back together
So, I finally got the PCV system installed. As I mentioned it turned out that the rear carburetor had a plug full vacuum port. Since there wasn't enough room to install a fitting on the rear carb I swapped it with the front carb. The PCV valve is in the driver's side valve cover and it draws in air from filtered vents on the passenger valve cover and the oil filler tube. I'm pulling 17 inches of vacuum I just hope the volume is enough.
I recently added a PCV valve to my coupe as oil was getting on the screen from the filler tube. I had already added moon style breathers to both valve covers with some help. This time I added a PCV valve to the filler tube and plumbed into front carb. I have only used car twice with no oil on screen. Glen
Won't the front cylinders end up a little leaner with the PCV in the base of the front carb; seems to me flow would be better balanced if the PCV was connected to the base of the center carb.
If it is an open cap rather that a closed cap (filtering media) it is not functional. Even with a closed cap, just the rocker cover vents will not successfully ventilate the crankcase.
Both the passenger valve cover and oil filler tube are vented using filtered breather caps. The front carb may run a little lean but I couldn't connect it to the center carb port because it is used for distributor advance. I'm running a progressive linkage that doesn't kick it until at least half throttle. That said, you did get me thinking I need to recheck the air/fuel mixture at idle as it has probably leaned out a bit.
The Jalopy Journal
