tgilligan

Hi All,

Tracked down a vacuum leak to the intake manifold and the carb base gasket so tonight I removed them, cleaned all mating surfaces and put new gaskets and sealant. For the valley pan gasket, the dimple locators were really pissing me off but I had them where I wanted and I placed the intake on after putting sealant around the ports. My OCD is worrying that maybe one of those dimples popped out a bit but all of my bolts went in smooth with no obstructions. Is it safe to put my mind at ease that as all the bolts went in smooth that the dimples held and my pan didn't shift at all?

As to the vacuum portion, I wanted to get an idea as to what others are set up like. It's a stock 350 automatic with AC, points dist and stock cam. Valve train setup was changed to Comp Cams and the intake is an Edelbrock Performer with a QJet 4 bbl. I bypassed my TCS solenoid and am running dist advance directly to the ported vacuum port on the front of the carb. However, currently it's removed all together and capped as I'm in the process of setting/adjusting timing. Other than that, I have the trans line running to a tee fitting which is then going to the TVS tree at the front passenger side of the manifold and the other side of the tee is going to a port on the intake runner of the manifold. Everything else is either capped or plugged. I don't have a brake booster yet and there are no other connections. It's fairly minimalistic at this point and I want to make sure I'm not missing something or routing something incorrectly. Thoughts?

oldcutlass

You can remove the TVS and run you trans vacuum direct to the manifold port. Also you can run your vacuum advance to the manifold vacuum port on the carb and then readjust your idle speed down to what it needs to be. You won't know about your intake until you start the engine and you have no coolant, oil, or vacuum leaks.

tgilligan

Thanks. So I tested and no leaks and running much better with what seems like a new issue. What does it mean when vacuum reading at a fitting on the manifold is steady at 17-18 but when I hook the vacuum gauge to the bottom port of the carb next to the pcv, I get little to no reading? I tried the ported vacuum fitting just above that on the actual bowl of the carb and got same, nothing. Is that a carb issue? I'll include a picture of the two ports in referencing.

oldcutlass

One fitting is considered manifold vacuum and should have vacuum at all times. The other is ported and should have next to or nothing at idle. If your raise the rpm with the throttle as soon as you are out of the idle circuit you should have the same as the other port.

tgilligan

Interesting. I've got zero out of the bottom port of the. Are at all times. If I hook it to the port ok the actual manifold I get a good reading. Could the gasket be blocking the port? Any other items I could look at to remedy the problem? Since I'll be using that bottom port for dist advance I want to make sure I have a working port.

oldcutlass

Yes, the gasket, sealant, or dirt could be the issue. If the carb is functioning fine and you don't want to take it apart, you can tee off of one of the ports direct from the manifold.

tgilligan

Thanks again for the help. Turned out to be the gasket. I took it off and did a small amount of surgery to it to prevent it from blocking the inlet at the bottom of the baseplate. Now I'm pulling a steady 12 inches at that port.

oldcutlass

You should be pulling the 17/18 same as the manifold.

tgilligan

You had to burst that bubble huh?...kidding.

Ok so if I only have a couple of vacuum connections and those are not leaking, I've sprayed starting fluid around the intake and base gasket (both just replaced) and found no leaks, what other things should I check for?

oldcutlass

I would just Tee off a manifold port for your distributor.