A QUICK QUESTION ABOUT MANIFOLD VACUUM

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Well, I cleaned the hell out of it and blew out all of the passages and installed a new kit and adjusted it to the OE specs. It actually looked really good when I first received it. It was a late 70's take off from a Barracuda and then shelved. No evidence of dried fuel or varnish. LOL...It was delivered in a '70's Holley box so I can imagine the story.

BTW....Pardon my ignorance, but what does IFR stand for?
 
CFD244 said:
Well, I cleaned the hell out of it and blew out all of the passages and installed a new kit and adjusted it to the OE specs. It actually looked really good when I first received it. It was a late 70's take off from a Barracuda and then shelved. No evidence of dried fuel or varnish. LOL...It was delivered in a '70's Holley box so I can imagine the story.

BTW....Pardon my ignorance, but what does IFR stand for?
Click to expand...
Idle Feed Restriction. If you pull the top off and turn it upside down you'll see where the the fuel travels up at an angle towards the booster outlet. Inside there is a little pressed in tube that should measure 31 thou from memory.

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Some ignorance about idle timing on this thread. 25* with a mild cam.
The engine in question has well over 200* @ 050 duration on the intake. It has 9.3:1 CR.

Consider this engine: 10.75:1 CR. 197* @ 050 intake duration. Note that, all else being equal, a higher CR reduces the amount of idle timing reqd. These are the specs for the engine in my GTO, as it came from the factory. It idled with 26*. 6* initial with 20* added via MVA. With the current cam, it idles with 48* in Drive with a near smooth idle. Many stock Chevs idled with 24*.

Note below the idle timing with short cams.

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