I was just wondering today as I was replacing vacuum hoses and vapor hoses for the charcoal canister...how does GM determine if a hose needs no clamp, a cheap spring clamp or a screw clamp for the smaller hoses? I was thinking maybe fuel hoses got the screw clamps, vapor hoses got the cheap spring clamps and vacuum-only got no clamps at all (if they fit really tight) but the canister hoses are like half and half and some of my vacuum-only hoses do have clamps. I would think every hose would get some kind of clamp but that obviously is not true on my oem tbi setup.

 

If the line pulls vacuum, it generally does not need any clamp force to retain
On a turbo car, where systems see positive manifold pressure, many connections are secured w clamps.

So under pressure, clamp. No pressure or vacuum, clamp. How much, depends on what's used.

 

Basically what he said.

I will add that these are THE professional way to clamp boosted application vacuum lines:



And you want 50psi rated silicone also. XRP in California is our supplier. Very reasonable for bulk 50psi rated vacuum line.

GD

 

I would add also that the "cheap" spring type clamp is WORLDS BETTER than the worm gear type in most situations; not least because, it's impossible for it to lose clamping tension by way of the hose material compressing underneath it and causing a leak. Too bad they can be such a PITA to get on and off during service.

 

Most vacuum lines aren't under enough pressure to be a problem. Even on a boosted application, if small diameter vacuum line is properly sized to the barb it's pushed onto, it's not going to blow off without a clamp.

Boosted 23psi in my Mustang, and I don't think that car has a single vacuum line under 3/8" diameter with a clamp on it. Blew the silicone coupler and T-bolt clamp off the throttlebody one time, but have never blown a reference line.

 

Good info thanks guys!