Do I have a vac leak or a big cam.

[TexasNomad]

Hiya every one. I got the beast running to day my 79 f150 with the 460.
It seems to run very well very responsive on the throttle.
Ok here is the issue, i'm pulling about 16 17 on the vac smooth idle, pcv valve is fluttering new just installed, I can adjust the idle mixture's but when I bottom either one out the engine just sputters and won't die, this is how I was shown to tell a P valve is blown well its not, brand new valve,can't find any hissing or broken vac lines.
So I was thinking, something is wrong with the engine or when they rebuilt this engine could they have installed a larger cam like a RV or maybe bigger? and thats why I have the low vac and maybe the Pvalve i'm using is not the right size (6.5) and maybe need to go to a bigger/smaller? what do you guys think on this? I took a little vid of my vac gauge so you could see how it looks when I give it a fast large rav and just bump it, any help or ideas would be awesome thanks guys.
http://s10.photobucket.com/albums/a145/Thenomadrhodes/Autos/?action=view&current=vacgauge.flv

 

[blacksnapon]

While 16-17 is on the low side, its not unusual for a big block such as the 460. Because you have a smooth idle, the big cam is unlikely. Remember, the 460 went away because it is a "dirty" engine, as far as tailpipe emissions are concerned. You can use the "hillbilly" method for checking vacuum leaks. When the engine is running, put your hand over the carb, shutting off the air. A drastic vacuum leak will allow the engine to keep running. A slight leak, you might have to use carb cleaner, sprayed around the top of the motor. When you spray the cleaner on a vacuum leak, the sound/speed of the engine should change.

 

[TexasNomad]

While 16-17 is on the low side, its not unusual for a big block such as the 460. Because you have a smooth idle, the big cam is unlikely. Remember, the 460 went away because it is a "dirty" engine, as far as tailpipe emissions are concerned. You can use the "hillbilly" method for checking vacuum leaks. When the engine is running, put your hand over the carb, shutting off the air. A drastic vacuum leak will allow the engine to keep running. A slight leak, you might have to use carb cleaner, sprayed around the top of the motor. When you spray the cleaner on a vacuum leak, the sound/speed of the engine should change.

thanks for the reply man, but by smooth idle I mean I dont see the rough idle that one would see with a leak, but the truck goes glug glug and the truck rocks back in forth. the only big block i've been around has been drag Chevy Mopar or stroker ford engines.. But i'll try the Hillbilly Method, that red neck ways all ways work better hehe.

 

[d-kuzmen]

You can also use water dump it around the carb and intake gaskets, you'll hear it sucking if you've got a leak. I honestly think you engine is running normal.

 

[TexasNomad]

You can also use water dump it around the carb and intake gaskets, you'll hear it sucking if you've got a leak. I honestly think you engine is running normal.

So the engine not dieing when I bottom out one of the idle screws is ok?
I was told that means some thing is wrong, still learning about allot of this stuff.