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Re-attached a rebuilt carb and my car is very jumpy. Have seen posts online suggesting vacuum issues. I retightened my carb and will torque wrench it tomorrow but am going to test vacuum to see.
any other usual suspects for what it might be.
Before collecting all sorts of descriptions about where to attach a vac gauge, please post a couple photos of the top of your engine without the air cleaner installed. Then you'll get advice that applies to your exact engine.
You can TEE into either of these hoses if you need to drive the car with the gauge hooked up. If not driving, just disconnect the left side of the lower hose at the distributor and connect the gauge. If you're wanting a permanent vac gauge connection, you can replace the hex fitting that connects to the brake booster hose with a 2-port fitting.
Thank you. So I connect it by the lower arrow as opposed to the valve by the carburetor?
I don’t need while driving. Just want to check pressure in idle.
Thank you. So I connect it by the lower arrow as opposed to the valve by the carburetor?
I don’t need while driving. Just want to check pressure in idle.
Yes the lower hose is the distributor vacuum advance. If you are setting the carb mixture screws via vacuum readings there's no problem disconnecting from the advance can. Your idle will probably (should) drop and will need to be temporarily raised to reset idle speed. After setting mix screws to maximize vacuum, reconnect the hose to the distributor, and reset the idle speed.
To check the vacuum, just pull the tubing off the vacuum advance nipple as shown by the yellow arrow and plug your vacuum gauge into the tubing you pulled off.
As suggested use your PS vacuum line. Cut an inch off the line. Go to NAPA or another auto parts and look for a Tee that fits the PSV hose + provides a 1/4" outlet for your Vacuum Gauge. Connecting to distributor vacuum advance is not the best source. You need to connect to Direct Vacuum on a line directly feeding off your intake manifold. If your Holley carb has a port for direct intake vacuum it's usually on the bottom front of your Holley and likely capped. A handheld vacuum gauge is a handy tool which is why I mounted a small vac gauge just above my parking brake under the dash for quick reference at any time.
As suggested use your PS vacuum line. Cut an inch off the line. Go to NAPA or another auto parts and look for a Tee that fits the PSV hose + provides a 1/4" outlet for your Vacuum Gauge. Connecting to distributor vacuum advance is not the best source. You need to connect to Direct Vacuum on a line directly feeding off your intake manifold. If your Holley carb has a port for direct intake vacuum it's usually on the bottom front of your Holley and likely capped. A handheld vacuum gauge is a handy tool which is why I mounted a small vac gauge just above my parking brake under the dash for quick reference at any time.
all he wants to do is check the vacuum he is not modifying or adding anything yet. Pull off the vacuum tube to the vacuum can, measure the vacuum, plug it back on you don't need to go buy anything.
65GGVert....I get it Bub. I know CW85 was asking "how to connect a vacuum gauge"..albeit for his diagnostic.
All I suggested was what one can also do (especially if inserting a Tee in PS Vac Line as mentioned above) is use that T-d Port for constant vacuum reading with a small ($20) vacuum gauge installed.....like this.....don't see how that can hurt.
