The setup I have is PVC valve in passenger side cover with hose to carburetor base. Also have breather cap on drivers side cover, will this cause vacuum loss?
No. You have to have a way for the fresh air to get in after the bad air is sucked out through the PCV valve. -Dave
Pcv valve works by closing off at high vaccum (eg at idle) and opening at low vaccum (eg full throttle). There will always be some vaccum lost through the pcv system but it should be minimal. If the valve is faulty it can sucks in too much air through and lean out the mix causing the engine to run rough and be hard to start. If you suspect this might be happening then pull the tube off the valve cover and stick you thumb over it. Sent from my SM-J320FN using Tapatalk
Yes, how much is determined by the number valve you use. The larger CID the engine will use a valve with more loss than a smaller CID engine. The valves look the same except for the number. Be sure to use a breather for it that has an element to be sure the in coming air is clean.
OK Thanks. The engine runs and idles good. Installed front disc brakes, dual master, 7"booster, don't seem to have much vacuum, haven't put a gauge on it yet but have hard pedal to get brakes, Did the pump brakes up and hold ,start engine and pedal doesn't drop at all. Had even installed a vacuum canister reservoir.Will have to do some tracing and checking hoses/fitting.
did you connect the brake vacuum to the same place the PCV vacuum is connected? or did you connect it to the manifold, directly, to an appropriate sized fitting?
Valve could be problem, I installed the one that came with the valve covers. Breather is the doom type with the venting under the cap.
Bleed the brakes again. Problem may not be vaccum. Also brake booster should have direct manifold vaccum and not have a pcv on it. Pcv line should be separate. Sent from my SM-J320FN using Tapatalk
Ran off the manifold port behind the carburetor to the reservoir canister, then one line from canister to booster and another line to the tranny. There was 2 exit ports on the canister.
Bench bleed the master, and bleed all brakes starting with the farless away. The pvc goes from the valve cover to the back of carburetor base, not in the vacuum line
pictures would be helpful. The transmission vacuum line needs to be connected directly to the manifold also, not to a reservoir.
Just thinking on the brakes, you have the check valve in the vacuum line to the booster installed in the right direction if you have one of those valves that you cut the line and put it in the hose? That could be with the vacuum reservoir too. Hoses backwards and it doesn't work.
Most or all modern add on boosters include the check valve in the plastic fitting that is on the booster, where the vacuum hose connects.
The tranny hoses is at the very back of canister, hard to see. The only fitting that came with canister goes from canister to the booster
Just trace the fault. Is booster getting enough vaccum? If yes the booster is at fault. If not then trace the vaccum lines back to the carb by pulling the hoses and checking for vaccum at idle. If engine wasn't developing vaccum it wouldn't run. If you have vaccum everywhere then you may have a leak. To find the leak spray brake clean on joins and listen for change in idle. Sent from my SM-J320FN using Tapatalk
I suggest you do an experiment...remove the reservoir can, connect the brake booster and the transmission to a T fitting on the intake manifold, and see how it works.
Why the vacuum reservoir? Is the cam a large grind that produces little vacuum? I've never used one, but other folks have reported poor results from the small aftermarket brake boosters. -Dave
Will try the tee experiment tomorrow and report back, if no change will try tracing as Mantula Man suggests
I have little experience with those little boosters, but it's similar to what we see here...the booster is just too dang small.
The motor was rebuilt when I bought the car, owner said it had a mild cam, probably over kill on my part just thought it would be better
That's what I was wondering after reading some older post. I bought the entire setup from Speedway, Firewall pedal assembly, 7" booster, dual master. I bought the tool gauge for setting distance of the pushrod between the master and booster so pretty sure that's set right.
You need a lot of vacuum for the booster I would not worry about the trans modulater right now. The fitting on the intake manifold should be on the larger hole size about a 3/8 inch opening just for the booster. Don't know about the canister except what was stated before about the cam. Put a vacuum gauge on the manifold fitting and read what you have. Should be at least 14-18 inches of vacuum. After that if that fixes the brake problem then find a vacuum source that is full vacuum at idle off the carb. Then install the trans line to it.
The hose you have connected to the booster is coming off of a one way valve just like the one on the booster. The hose on that valve should be going to manifold vacuum. The way you have it connected.. you aren't getting vacuum in the cannister.
Definitely do what Jim told you. I was wondering why you put such a small booster on that car. Small 7 inch are great for small or light cars but I think you have the space. See if a 9/10 inch dual diaphragm booster would fit. 70s Monte Carlo , Chevelle's came with bigger than what you have. Good luck.
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