Hey everyone! Fist Q is--how did the main vacumn line route when it leaves the vacumn tree on the intake? {OH LS-5} Did it take a left and follow the power brake line and enter the hose harness or did it go left behind the distributer and go under the wiper motor? Where is the filter and check valve supposed to be! Second---my A/C works great but the 2 vent doors on the rite side that flap open and closed in the MAX setting quit working. I know both vacumn canisters are good and don't leak--checked with my vacumn guage Mytivac! I think it the vacumn switch that is mounted to the control assy in the center console!!! I can't find the part # for this piece! Maybe uncle JOE can steer me in the rite direction! Thanks Thad #32187
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Re: 1970 Questions
My intake vacuum port has a short rubber hose (about 6") connected to the vacuum filter then to the right side (passenger side) of the distributor. The hoses then lead under the wiper motor to the check valve. The other ports of the check valve lead to the vacuum tank, lights, wipers, etc. I do not have power brakes so I am not sure where that vacuum source to the power brake booster is directly connected to.Tony -
Re: 1970 Questions
Thad: The NCRS office has Service Manuals for sale and the one for 1970 is $35. In this manual there are diagrams and trouble shooting guides for almost anything. Also available is Vette Vues Fact book 68/72 which has many pictures of engines from both sides for all those years which could be helpful, Cost $32. The Assembly Manual is very helpful with pictures and part numbers for almost anything on the car. These parts are not always available but it's a start. That AIM is $17. These books and the judging manuals are PRICELESS when trying do shoot trouble or locate something on these cars. Good Luck!Comment
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Re: 1970 Questions
Thad-----
The heater/AC vacuum control valve which you seek is GM #7309782. It currently GM lists for $37.89 and will be a special order item at just about all dealers.In Appreciation of John HinckleyComment
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Re: 1970 Questions
Thad,
There are variations in '70 Corvette vacuum hose routings, and I am not sure what the determining criteria are; maybe early/late production. The AIM, presumably the last revision, shows a configuration different from what was on my car (built last production day), so I am not sure the AIM version ever made it into '70 production.
For what it's worth, here is what my base engine, air-conditioned car, with power brakes had: From the manifold fitting, 6" hose to filter, 4" hose to check valve. One outlet from check valve passes with harnesses over PB booster to vacuum reservoir. Second outlet from check valve (apparently) tees with one branch going into firewall grommet near the PB booster to supply vacuum to the headlight/WSW vacuum harness behind dash cluster. Second branch of the tee passes behind the wiper motor to enter AC firewall grommet on passenger side of firewall, and supplies vacuum to AC controller valve in console. I believe all hose up to this point is black (no stripe), and from here it gets very complicated in a hurry. You'll need an AIM or some kind of schematic to proceed from here.
On my car, the distributor vacuum advance/TCS solenoid harness is fed by a vacuum tap off the carburetor. The power brake booster has a dedicated manifold fitting with about a 5/8" diameter hose that goes directly to booster check valve.
The AC outside air valves are both controlled by a green striped hose from the AC controller valve. This hose tees under the dash with one branch going to the right side kick panel valve, and the other branch exits through the AC firewall grommet, and passes back through the firewall into the plenum to operate the plenum outside air valve. If you can apply your Mityvac to the green striped hose at the AC controller (it has a special multitube connector) and can make the valves open, you can confirm the problem is in the controller.
Chuck SangerhausenComment
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Power Brake Comments Revised
Thad,
Re: Power Brake vacuum connection: My earlier post said it was a dedicated manifold fitting, which is totally incorrect; Several vacuum taps, including the power brakes, are made off the same manifold fitting. The power brake vacuum tap has a flared type tubing connection to the manifold fitting, with a cad/zinc plated tube or pipe that extends across the rear of the engine toward the PB booster. This tube has a support bracket that attaches to the throttle cable bracket on the carb. A large rubber hose, seem to remember about 1/2"-5/8" OD, attaches to the end of the pipe with a spring type hose clamp and completes the run to the booster. Sorry about the misinformation, and I hope it hasn't caused you any inconvenience.
My memory is starting to go; I need to get this car back together fast before I forget everything!
Chuck SangerhausenComment
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