I'm still convinced i have a vacuum leak. I have my vacuum system that controls my headlights and wiper door plugged off. It ran rough with it connected, so i just have a PCV hooked to the main port on the carb. Still runs rough, yet its alittle better, however at least its running. i can't see any noticable leaks , or oil leaks. just lookin for some advice on my rough running. Thanks guys.

 

What carb are you using and do you have the correct gasket under it? Did you make sure the brake booster is not causing the issue?

 

Remove every hose, including the PCV, at its source and cap the source. You won't harm anything in doing this. Start the engine. Take a can of WD-40 and start spraying short bursts around the carb at the base where the gasket is. If you find a vacuum leak, the engine will momentarily smooth out. All you're looking for is a change in the way the engine is running. Whether you can define "smoothing out" doesn't matter. If you find nothing around the carb, work the intake manifold to head surface.

If you don't find anything in the intake system, you can start plugging in vacuum hoses one by one. If you plug in one that has numerous junctions that causes a faulter, then unplug and cap the hoses at the various junctions until you eventually trace the source of the leak.

 

With the engine idling, try pinching the vacuum lines,with needle-nose pliers, starting at the check valve at the intake. The engine will smooth out when you pinch off the offending line. Keep following the line to the destination, the headlamp relays. Pinch off each supply line to find out which side of the system is leaking. Either the relay itself is leaking, or the h/l actuator seal is ruptured. You can hear the vacuum leak if your hearing is good. G/L

 

You probaably won't find an oil leak with your vacuum leak. Look at all of your vacuum hoses for evidence of weather cracking. If even one is cracked, I would reccommend making a vacuum map if you don't have one and replace all of the vacuum hoses from smallest to largest. Then while you are at the auto parts store getting new vacuum hoses, pick up a can of starting fluid (ether). With your hood open and the engine idling, carefully spray the starting fluid around the base of the carb, at the base of all vacuum fittings, and on the hoses and any vacuum pots. Spray around the intake manifold as well especially the ends in the valley where they typically use cork and most people dispense with the supplied cork gaskets and use silicone. If the manifold has been sealing, it probably won't leak now, but better to be sure. Keep the fluid out of the carb. intake. If the idle speed suddenly picks up when you spray, you've found your leak. You can also do this with wd40 or anything flamable, but ether works best. The little bit of ether that gets in won't hurt your engine, unless you have such a big hole that you are shooting ether directly into the engine. When I say "spray," don't try to empty the can with each shot, just a short one second "spritz" at each place is plenty. You are looking for the engine to pick up speed from the ether, not run it on ether.

 

I'm using a Street AVenger carb..right gasket and no power brakes. I will try the ether method and thanks for the other information guys.

 

TRUE STORY:

On my '80 L48, I eventually purchased every vacuum line kit and system component from Dr Rebuild. I started with the "easy, underhood kits": Evap, EGR, EFE, PCV, cruise and headlights. Then, I progressed to the vacuum control on the heat/ac switch in the shifter console (not sure if your year uses vacuum on the console switch or not). I found some vacuum leakage on that switch so I replaced it along with short sections of each of the color-coded hoses/lines that run into it. Also found and replaced the small thin-wall plastic lines/hoses that pass through the firewall that tee'd off of the brake/cruise/headlight lines (not sure which of them it was...) that were brittle/cracked. Then, I removed every single heat activated vacuum solenoid/switch from the intake manifold and updated my hose routing to accomodate their removal. Then, carb rebuild, intake gaskets, new distributor with ignition recurve, timing and carb mixture.. AND both the plastic filter/can that connects to the power brake booster and the plastic fitting that attaches the hose to the brake booster. Effectively every hose and plastic fitting that touches/processes or relies on vacuum signal from my vacuum system.

AND THE ENGINE FINALLY idled like it should (ie. LIKE NEW...) Go figure...

Thankfully, my '69 is so simple. Just have a few hoses between the carb/distributor and PCV to worry about. Oh, and the headlights, wiper door of course

BTW, sweet looking Red '69 Stingray vert.