Vaccum leak found.
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Joined: Nov 2005
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From: Collierville
Vaccum leak found.
This Sunday I was installing my new AC in my 77 and i crawled up in the engine bay to install the vacuum line for the system. I found a port on the back of the intake. There were 5 holes in it and the larg one at the back had a clamp on it over the rubber cup. Three of the other ports had been blocked off witha peice of hose with a screw in them. I know that because they had rotted off and fallen on top of the intake. The rubber was gone off the end of the large hole. The 4 th hole was hooked to the trans vacuum port. The point is that there was a huge vacuume leak in the engine that I didn't know about. I bet that was why the trans would seem to shift late when it was downshifting to pass. It was amazing that the engine ran so well like that. I knew there was a small leak somewhere but I thought it was between the carb and the intake.
The lesson is check for vacuum lines off every time you open the hood when the rubber is 30 years old
The lesson is check for vacuum lines off every time you open the hood when the rubber is 30 years old
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Joined: Aug 2005
Posts: 2,760
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From: Gadsden Purchase
Originally Posted by rboeding
The lesson is check for vacuum lines off every time you open the hood when the rubber is 30 years old
I was having vacuum leak problems with what looked and felt like brand spanking new hose. My friend handed me the reel and told me to use what I needed. For a few years I had small problems and corrected them as they popped up, finally it dawned on me what was going on. :) I mentioned it to him and he laughed that he'd later figured out the same thing. :)
I've switched all my small vacuum lines to braded fuel line. 3/16" fuel line isn't the easiest thing to find, but so far at least, I figure you only have to find a source of it once. ;)
I removed my "tree" and cut off un-needed ports and then tapped the holes for whatever size machine screw size would fit best then Permatexed (new verb) a machine screw in. Got any old brown Permatex? :) Mine was an old tube when it was given to me when I was a kid. (thin with a little alcohol when needed)
That old brown Permatex is gasoline resistant, BTW.
Alvin in AZ
Lead Driver
Joined: Jun 2006
Posts: 5,665
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From: Near Yosemite CA
Yep!! I just rebuit the 2bbl on my 77, the gasket below the EGR valve was blown and sucking air, 2 vacuum lines had cracks BIG cracks. So I am going to rplc all of them and get rid of all that vacuum tree on the backside of the intake. Anyone know the best way to adjust the carb now? She has more power, but I think there should be a bit more. btw it is a 351Measly w/4speed
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