VCCA Home Forums TECHNICAL - 1945 AND NEWER 1990-Current Vacuum diagram???

Pulled a 305 with a quadrajet out of a '90 one ton truck to put into an old F---. Didn't take pictures of where all the vacuum lines ran. Is all that stuff necessary? I was thinking of just using baling wire for the choke, etc. Is there a diagram available?? Thanks a bunch!!

There is probably a vacuum hose diagram in the 1990 shop manual for the truck.

Check with your state emmissions control folks first, but most of the vacuum lines are unnecessary when the engine is moved to an older vehicle. Emmissions controls are required according to the vehicle the engine is in at the time, and if you are not transferring the controls, you can get rid of the hoses.

So, you still have to have a diagram of what they are for to decide whether you need them. The basics for the engine (distributor and carburation) are necessary. Most everything else can go.

Timing and carburation will be different without all those emmissions checks, so go back to an earlier manual and start from one that has little to no emmissions equipment. Do your adjusting with tach/dwell meter, vacuum gauge, and timing light for best results. Be sure that all unused vacuum ports are securely capped.

Baling wire for the choke!? For choking a chicken, or what? The "choke, etc." should be self contained, though I suppose you could run some baling wire through the cowl of that old F#*& for the throttle...... Just put a loop on the end of it to pull on when you want to go.... Be sure to have a strong spring on the other end to pull it back! :-)

The 90 model 305 should have a TBI rather than a Q-jet. I think that you could just use starting fluid to start the old 305, forget about using all that baling wire, put it back in your tool box along with the roll of duct tape and the pliers!

Thanks guys! The engine actually came from a truck (and I understand that it had been re-engined) and it came with a QJ. Does anyone know where the vacuum advance connection comes off the carb?

That depends on which Q-Jet carb, and intake manifold you have. Do you have the engine number and casting numbers checked out to determine which engine it is? Is this a stripped engine? Man there are a ton of different SB 305 engines out there.

I have a 1970-87 Chilton Chevy Pickups and Suburbans manual. While it doesn't give specific diagrams, it goes through the basics of all the emmissions controls, what they look like, and where they hook up. It can be an educational experience to go through such stuff. Oops; turned the page and they do have some diagrams that should show you what you need.

If I remember correctly, most of the vacuum connections are on the front and rear of the carburetor base with secondary connections like temperature sensor, EGR and such spread around the engine. Remove anything you don't need and plug it. If you need one connection where there are three or four, remove the gang connector and replace it with one that has only the number you need; it just looks neater.

The vacuum advance may have two connections to it; one straight from manifold vacuum and the other through a bypass valve. You can most likely get by with just the straight one that comes off the front of the carb, second one from the passenger side; depending on the carb used.

There is usually another vacuum inlet directly into the manifold for the automatic transmission and PCV valve; keep the PCV.

It looks like 1977 was the first use of the 305, and that would probably be the best starting point for tune up specs with most of the emmissions controls removed.