Sid

I have removed the road draft tube and run a pvc valve to center Carb on my 3 duce setup it does not seem to be working correct as I keep fouling plugs and keep getting a lot of suet at start up, I was wondering if some of you have had any dealing with this and could clue me in, the engine is fine and has been rebuilt and it is not the problem, I know that the road draft tube can be removed and it can be successfully done. I have added breathers to both valve covers , hope to find out what I am doing wrong.

Thank You ,SID

64Rocket

May have to reduce the vacuum to the draft tube. Maybe just plum the draft tube with small hose to the bottom of the air cleaner. Just like the draft tube used the draft going past the tube. .Plum it to the bottom of the air cleaner with small hose, like 1/2 inch. The draw from the air cleaner should be enough.

joe_padavano

Where did you put the PCV valve? Soot at start-up is unrelated to the PCV. When you say "fouling plugs" do you mean oily residue on the plugs or dry black soot?

oldcutlass

Is this how you did it?
From the center carb vacuum line to the block?

classicmuscle442

Sounds like engine is running rich, correct outer carbs?

Sid

Thanks for all the reply's, will check all. I ran the line to the center carb base like in your [pic.
SID

oldcutlass

You can block off the pcv for a while to see if your issue clears up.

Tedd Thompson

Also your engine is vented through the oil filler cap could this cause the problem by not being a sealed system?.... Tedd

shiftbyear

Just wondering if you have some kind of baffle around the PCV valve. If it's exposed to direct splash oil it won't work correctly. Valve covers have baffles to protect the PCV. It's only suppose to remove fumes. I've been heavily researching PCV valves recently and came across this adjustable unit I want to try. A little pricey but I talked to the owner and I'm sold. Good luck with your project.

http://mewagner.com/?p=444

Sid

I've installed a pvc valve on my 57 371 in place of the road draft tube and been having a lot of black carbon at start up, have 3 duce set up on car and ran the valve thru the center carb also I installed breathers in both valve covers , Have I installed the vale correct by running it thru the center carb?. Would apricate any feed back on what I can due to fix.

Thank you----SID

joe_padavano

The PCV valve simply needs to be connected to manifold vacuum. Typically this would be a port in the carb throttle body, but it could also be a port on the intake itself. The other end of the PCV needs to be connected to the crankcase volume. This could be a fitting at the old road draft tube connection, or it could be one of the valve covers, or it could be through the valley cover. On my 62 F-85, my valve covers each had a filler cap. I used one vented cap and one cap that had a port for the PCV valve.

Greg Rogers

Had a friend who hooked up a PCV valve to a Ford flathead. He found he then brunt a lot of oil. Long story short, he found that the valve sucked oil when it opened into the intake manifold because the oil tended to puddle there at the new PCV location. So make sure the valve isn't where it is picking up oil. Factory PCV valves are shielded in the valve cover from oil spashing.

oldcutlass

I merged your last 2 PCV threads for some history. And this link below is the thread about oil coming from your draft.
https://classicoldsmobile.com/forums...t-tube-110577/

Since you've had an oil issue with the tube I think the PCV is just making it worse. You now have breathers in the valve covers, block off the location in the block and relocate the new PCV to one of the breather holes in the valve covers,

Tedd Thompson

The outside carbs are like a toggle switch (vacuum operated) they only work at full throttle and will be closed until full throttle on the center carb... Tedd

joe_padavano

The port for the PCV is below the throttle blades. It sees manifold vacuum whether the carb is open or closed.