Bahrbarian Posted August 4, 2023 Report Share Posted August 4, 2023 Hopefully I didn't miss this in my searches, but I'm trying to find a vacuum diagram for my 73 L16. All I've been able to find is one for a 78 L20, which is a great thread, but not the same carb as my 73 620. I'm chasing I rough idle, (not bad, and got better with idle mixture adjustment and other hints I got from the forum, thank you!) and I see the PO replaced some vacuum lines with soft yellow tubing and capped one of the lines off from the base of the carb. I'd like to make sure things like my vacuum advance are connected to the proper spot on the carb and elsewhere and not switched around to the wrong vacuum source. Thanks in advance for any help the forum can give! Quote Link to comment
banzai510(hainz) Posted August 4, 2023 Report Share Posted August 4, 2023 (edited) 73 is from the carb baseto the dist that about it. soem where slip on hose or threaded. If threaded I just slipped the hose over the threads and called it good then the the ajustment as you did for best idle mixture then adjust the rpm speed screw Edited August 4, 2023 by banzai510(hainz) Quote Link to comment
datzenmike Posted August 4, 2023 Report Share Posted August 4, 2023 There will be a hose from the valve cover side of the carburetor base to the vacuum advance on the distributor. Make sure that is functioning. Pull distributor cap off, pull hose off the carburetor end and suck on it. The rotor should turn clockwise about an inch. It should hold position till you release it. If so, presume it to be working. There will be a vacuum hose from the left side of the intake below the carburetor up to the ATC (automatic temperature control) on the snorkel on the air filter housing. Pinch closed when idling. If it improves then there is a leak in it. There will be a garden hose size vacuum hose from the large metal pipe sticking out between the exhaust manifold to the PCV (positive crankcase ventilation) valve mounted on and below the left side of the carburetor on the intake. While it should be connected it won't affect running. Pull PCV valve and shake it. If it rattles presume it's working. On the rear of the two intake runners is a fitting with a finger sized hose to the brake booster. Pinch the intake end closed. If idle improves there may be a leak in the hose or the booster has a vacuum leak. You don't say, but if you have an automatic there is a small hose and metal line from the fitting on the intake for the booster that goes to the modulator valve on the automatic. Again, pinch closed and if the idle improves there is likely a leak. You need this functional as this tells the transmission the engine load and up shift points. Quote Link to comment
banzai510(hainz) Posted August 4, 2023 Report Share Posted August 4, 2023 15 minutes ago, datzenmike said: pull hose off the carburetor end and suck on it. The rotor should turn clockwise about an inch I tryed that and it didnt move. I just push it with my hand and see it moves. I vaccum gun would be best but most poepl dont have one. just make sure the hose is on. Im sure once running the vaccum will move the dist more easlily Quote Link to comment
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