Welcome to the Zone > . Post some pictures of your truck, we'd like to :-B at them. Also, include your truck vitals in your signature, it helps when someone is responding to a question.
i also have a question about the thermactor, and this flap thingy in the exhaust. its on the 351W engine, do i need these things and on that note what about that giant egr (i think) on the left hand side (passenger) of the engine that hooks into the thermactor.
The flapper thingy on the exhaust is the heat control valve. It is there for cold start and works in conjunction the other half of the function that is mounted on the intake manifold (driver side). Without the heat control valve the engine will generally tend to refuse to move the truck until it is nearly up to normal running temperature. That thing on the left hand side as you look at the engine from the front is not the EGR. It is the Air control valve and if the system is running properly it directs the air from the air pump to either the heads or the CAT. The EGR is that thing behind the carb.
If you have a Duraspark II ignition or some aftermarket thing like a MSD then yes you can get along without them. I generally run without the EGR or the Thermactor system but keep the heat control valve system in tact since it makes the cold start and run characteristics much better than without it. Attached is the stuff that I normally have running.
-The Orange system is the heat control valve system as mentioned above
-The Purge system, (in black), is there to take evaporative emissions from the gas tank, (and the carb float bowls, if you have a 4180 carb). It is especially useful in the summer to keep the pressure inside the gas tank even. Without it the tank tends to over pressurize when it heats up from the sun in the summer.
-The (blue) throttle kicker is there to prevent the A/C from stalling the engine when setting at a light. I don't have A/C but use it to keep my idle up so the giant electric fan doesn't stall my engine when the fan kicks in with the engine idling. (I guess it is a black line on this diagram, sorry)
-The yellow system is the spark advance and needed in a Duraspark II system or something like a MSD system.
-The red system is the main vacuum feed to various functions.
-I also have the Air Cleaner Diverter Valve hooked up since it is also improves cold weather running.
Good luck,
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