Hi,
I formerly owned a '95 "bigbluriv" but now have a big red '71 Riv! It was a barn find and the shop I purchased it from that revived the car replaced the original Q jet with an Edelbrock 650. Although they got it running their efforts on the vacuum system does not seem correct. I tried to ask on the ROA forum and got no answers, just blasted for not having a Q jet on there. I would like to just get what I have to work instead of spending a chunk on a whole other carburetor right now. I attached a diagram via edelbrock, pretty much figured out the line that goes to the distributor and the one that goes to the intake manifold. The optional brake boost port in the back is running to a port in the firewall. The PCV port in the middle is plugged. The charcoal canister has a port attached to the gas tank vent(?) and then an open one that says CARB. It seems it needs a PCV valve.. somewhere. And the charcoal canister connects to the carb.. somewhere. FYI the car runs ok, just kindof rough and has some odor from the engine bay noticeable when the windows are down. Kindof like exhaust but not as strong. Thoughts?

 

First, the manifold vacuum port would go to a solenoid controlled valve on /controlling the charcoal canister so purge could be PCM controlled.

You are correct , there should be a hose going to the engine with a PCV valve at one end of it and the other end goes to the PCV port on the carb.

I would be a little suspicious of why they went to a different carb. Most places couldn't get the Rochester (Quadrajet) carb working right, but they were a good carb, and when carefully worked on worked just fine. You did have to know what you were doing with them.

 

Thanks for the input! The car was in a barn for the past 30 years so I imagine the original carb was gunked up. Most shops I know don’t have the patience or want to spend the money to have a quadrajet overhauled so the Edelbrock was the quicker more cost effective fix I assume. The struggle was real getting a running driving fixer upper boattail so I wasn’t going to quibble over something replaceable like the carburetor.. I’ve researched rebuilt quadrajets and it’s just not feasible at this time, a few bucks for a pcv valve and some hose is.

 

There is a lot to learn regarding PCV systems and their benefit.

Research at the time PCV systems were initiated was a lot more than getting rid of the road draft tube.

It was found that when a PCV system was installed , engine wear was considerably reduced on tear down and the manufacturers jumped on this with both feet.
This was explained to us at a GM Training facility..
It is not something most folks doing repair work had the opportunity to learn.

It was something very special to rebuild a Quadrajet, start the engine , do some fine tuning while the engine was cold,and have that engine run like a clock, perform well when cold and well when warmed up,very rewarding. .