Cam, Holley and idle speed, oh my...

[2nd Mustang]

I just rebuilt a second used Holley 600 as my first one had a worn throttle shaft, now the issue. Both Holleys idled at 1200 or higher as the car would really shake at 1000 or less and vacuum would really suffer. A Holley book that I have says "Engines with long-duration camshafts often will not idle at speeds under 1200 rpm." My Crane cam is a mild hydraulic roller with an intake duration of 222 and exhaust of 234. Is this considered a long duration? I have no clue, thanks.

 

[D.Hearne]

Your motor should idle at 600 rpms. My 331 stroker with a Ford Z303 roller and 1.7 rockers ( .587 lift-228 degrees @.050) does Sounds to me like you've got a vacuum leak somewhere.

 

[2nd Mustang]

Your motor should idle at 600 rpms. My 331 stroker with a Ford Z303 roller and 1.7 rockers ( .587 lift-228 degrees @.050) does Sounds to me like you've got a vacuum leak somewhere.

You might be right. I checked the torque on my Edelbrock intake and it was less than the initial 17 ft. lbs. of the initial torque sequence. I went to torque to the 25 ftl lbs. that Edelbrock recommends on their web site and Murphy stuck again, the torque wrench (20 something year old Craftsman click type) stopped grabbing, it will only grab in reverse, so off to Sears where I find out torque wrenches aren't warrantied for a lifetime, so I purchase a new one, and head home with the engine sputtering. I went to torque the intake (after letting the engine cool down) and only one bolt hit the 25 ft. lbs. with a click. I stopped on the other bolts before I snap one of them. I just hope they come back out! Still there? Now the idle is steady, although still high. A new intake gasket and bolts in the near future. So what size bolts are these, they have a 1/2" head. Thanks.

 

[D.Hearne]

they're 5/16ths NC. don't recall the length, just pull one and measure from the underside of the head to the end of the threads.I only torque small block intake bolts to 20 ft/lbs max especially with aluminum intakes. 25 is too much.