When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My '74 doesn't have an EGR valve. It's got an LT-1 engine from a '70 Vette. so I'm not sure what's correct. I bought it this way and it's always run great for 34 years. In the pic below, the PCV valve connects to the large port on the back of a Holley 750 carb.. The small line from the canister is the one with the arrow. It connects to a brass "T" on the manifold at the back pass. side of the carb. That brass "T" has a large port and (2) smaller ports. The large port connects to the power brake booster. One of the smaller ports goes back to the carbon canister labeled "CARB". The other small port tee's to the TH400 modulator and to the head light vacuum circuit. I'll probably need to try and look at a '74 with an L82 and a '70 with an LT-1 engine to try and figure this out or just put it back together the way it was only with a new canister and a new fuel separator valve.
On my 74 with the base engine, quadrajet and auto transmission
the PCV connects to manifold vacuum on the carburetor.
the vapor canister hose connects to ported vacuum on the carburetor.
does the EGR connect to ported or manifold vacuum?
On the 73-74 the EGR valve connects directly to the front lower right hand port on the Q-Jet. That would be manifold. Here's a photo showing my 73' EGR hose and where it is connected to the carb port. According to the AIM it is connected in the same place on the carb in both the L48 and L82 engines. It is also connected to this same port for the 454 engine even though the EGR valve is in a different location.
Tooch
Hi G,
My understanding is that for the 70 model year the Evaporative Control System was installed on all cars scheduled to be delivered in California.
The system was called out as rpo NA9.
It wasn't required on cars being delivered to other states.
Because it requires a different gas tank and cap I don't think it could have 'casually' been added to cars.
???
Regards,
Alan
Hi Alan, just had another look and there's no canister and no sign one was ever there so will have to look elsewhere for the cause of the smell. I had to replace the fuel pump a while back and it was much better afterwards then I spotted the diaphragm of the accelerator pump leaking so rebuilt the carb, again much better but if the garage is closed for couple of days the smell returns. There don't seem to be any leaks when driving, I've replaced all the flexible lines on the pump and from the hard line to the carb and while working over the winter on the gearbox and diff rebuilds haven't seen any sign of leaks so running out of ideas now.
Graham
If it has been a good operating system for 35 years, I would leave it as it has been, replace the fuel separator and rebuild or replace the canister and run it another 35.
If it has been a good operating system for 35 years, I would leave it as it has been, replace the fuel separator and rebuild or replace the canister and run it another 35.
If it has been a good operating system for 35 years, I would leave it as it has been, replace the fuel separator and rebuild or replace the canister and run it another 35.
Agreed! After my last post I started thinking about why change things now ... other than fixing anything that's broken.
03-02-2017, 04:24 PM
