I have a relatively new (1500 miles) 355, slightly lumpy cam, edelbrock air gap w/ a 600 CFM Holley. I'm running very rich and the last thing I can think of is vacuum. I had a 750 edelbrock and went down to a 600 holley but no change. 14 It is obviously not computer controlled anymore, I remember some lines going to the intake manifold..Where do those lines go to? Are there also any other lines that I have forgot to connected and such? Thanks in advance!

Dan

 

I did the same thing, but as long as your not leaking vacum you shouldnt be alrite,
the only lines I have hooked to my carb(edelbrock 600) and intake for vacum purposes are the brake vacum booster and the distributor advance.
you can also hook more up for PCV and for your vents, or for EGR or other things.
Try hooking a vacum gauge up to the carb)non ported vacum source) then adjust the mixture screws until you achive the highest vacum.

 

What year/model is the car? Different years had different lines for various devices. Do you still have an EVAP, EFE, AIR, and EGR systems?

 

The car is an 1986 Z-28, that was and is carbed. No EGR, No EVAP, I don't know what EFE is?? And the AIR is not installed at this time but I wish to put it back on soon. I noticed when I put the vent on in the car and put it on the highest setting it wasn't coming out the vents. It was coming out defrost?? Is this associated with the vacuum problems?
Thanks for the info..

Dan
"Crazy Cooter"

 

yeah, the internals of the vents are vacum operated, if it is not hooked up, it will come out the defrost, or wherever it was last working at.

this does not nesecarly mean a vacum leak though...unless you did not plug the part on the carb/intake that the vacum line hooks up to.

 

STT,

Early Fuel Evaporation is a system that uses preheated air from a stove (cover) on the exhaust manifold that is ducted to the air cleaner through a flexible tube. There is a Temperature Vacuum Switch that controls a valve at the end of the air cleaner snorkel to draw either this heated air or fresh cold air from the intake duct. There is another TVS in the intake that routes vacuum to the heat riser valve in the right exhaust manifold, forcing exhaust gasses to flow through the intake manifold crossover passage, preheating the carburetor and intake.

Lack of vacuum on the HVAC controls will cause all air to dump to the defroster outlets as Joshua said. Defrost is the default position for the dampers.

Your original vacuum routing should have been something like this: