CB radio gurus I need help

I have a M1008 with a CB that has a 4' whip antanna. I stumbled across a SWR gauge that hooks up in-line on the antana coax.
My CB has a SWR knob on it as well. What should the correct reading be for this type of setup?

A perfect Standing Wave Ratio is 1:1, but you'll probably never achieve that. A ratio of less than 2:1 is good, the closer to 1:1, the better. Here is a useful link:
http://www.walcottradio.com/standing_wave_ratio.php

Thank you, I will check out the link.

That is a great link. Thank you very much...

That knob will never calibrate the SWR, just so you know. It is simply to calibrate the meter to the antenna system. Four foot whips rarely ever give an acceptable SWR. The best thing for you would be a 102" stainless whip. They provide good SWR, and very good transmit and receive. With any antenna system though, the better your ground on the antenna mount, the better your SWR will get, up to a point. The antenna mounting bracket MUST BE mounted to a steel bumper or body panel, not fiberglass. There are many factors that affect you SWR, but we can get into that later if you don't have acceptable levels from this info.

If you can manage a military antenna on your truck, you can get a decent CB setup with only a little work.

I picked up a pair of SFB3512/VRCs to use with an R. A. Miller (RAMI) multiband antenna multiplexer (CB, AM/FM, WB, Cellular) - this antenna doesn't need a tuner if used with the multiplexer. From the attached data sheet you will see a trend to less than 2:1 SWR below 30MHz (CB is in the 27MHz band) - this is verified by Cobham tech support even though it was not the original design requirement. These antennas however are not great for AM receiving (way too low frequency), or cellular (way too high frequency).

Depending on the RAMI multiplexer version you find (eplace, etc...), you can run either one or two antennas - the RAMI dual antenna setup requires an antenna to antenna spacing of about 80" - which is nearly perfect when these are mounted on the NATO antenna mounts sticking out the side of the CUCV.

As jeepsinker mentions grounds are important - when you put a transmitter on a vehicle everything should be tied together electrically to make as big a ground as possible, since it's a virtual ground (tires insulate the truck enough to prevent a perfect ground). Big horizontal surfaces like hoods, beds, and roofs need to be tied to a common ground point, and preferably with a wide flat copper strap (thin round wire like what your headlights and turn signals use sucks at carrying RF energy).