My question is can I bypass my smog pump and a/c compressor by putting on a shorter belt. Where I live there is no emissions testing. The truck is strictly for off-road use only.....

 

Unless the pump is seized, you will gain absolutely nothing by doing this. The air pump takes virtually no power at all to run. You can guesstimate a belt length using a piece of string.

 

What is the air pump and what does it do?

 

the air pump basically run clean air into your exhuast between the two converters it just helps with the emissions

 

if you are going to remove the air pump you will need to plug where it enters the exhaust. also, i've heard that this can cause a problem with that cats. i removed my cats last fall and decided to get rid of the pump since it wasn't doing anything at all. i had pulled of all of the extra a few months ago but just finally actually removed the pump today. i have A/C on my truck still so i don't know what belt size you need for that. but after about 4 trips to carquest my 95 f150 4x4 351 with everthing minus the air pump is using a 2440mm length belt. i hope this is some help.