Hey there,

I'm in the process of replacing the head gasket on my 1977. Whoever owned the truck before pretty much destroyed the smog system already, I just want to remove it the rest of the way. I'm sure there is more too it than unbolting it and chucking it. What parts will I need and will it negatively effect performance? I'm assuming there will need to be some sort of carb spacer to fit in where I want to take the pump off, but beyond that I really don't know what else to do. Thanks!

 

I once owned a 1978 which had been butchered [smog cripple / delete] before I purchase it. I took the EGR adapter plate to a friend who owns a machine shop. He manufactured an aluminum plate of the same shape and height and bored the large hole for the carburetor and two smaller holes for the hold-down bolts. I went this route to maintain the correct geometry of the throttle cable. In hindsight, I might have considered using phenolic material instead of the aluminum to help insulate against too much heat getting to the carburetor [sometimes shows up during heat soak; after shuting down a hot engine].

You will most likely need to retard the timing some to prevent pinging since the EGR will not be in effect. The best would be to recurve your distributor. Use the "SEARCH" button at the top of this page and you will find much written about recurving distributors.

All vacuum ports will need to be capped except for the vacuum line going to the advance unit on the distributer, the PCV valve and the power brake booster. I don't believe the AC/vent system uses vacuum on your truck.

Make certain to place new gaskets under the adapter plate as well as between the adapter plate and carburetor.

You also will need to cap the exhaust manifold where the EGR get the exhaust gasses [3/4" plumbing, I believe?]

 

I should have taken some pictures before I took most of it apart. But the PO really hacked it up. Every line except for the EGR from the exhaust was removed or plugged in some fashion. I'll try to get some pic's up today since it's still on the truck, just disconnected from the intake manifold.

The truck ran fine before with basically everything disconnected.

Could I use a throttle body spacer to account for the lost height of the thick metal hunk (my apologies for the technical terms, lol) that connects between the carb and manifold?

 

FWIW while you are cleaning this up, check the EVAP system. It does nothing to harm power, but once it's damaged or butchered it can be expensive to fix if you need to. Just be sure your tank is vented, either through an intact evap system, or through a vent that is routed outside the engine compartment. Hacked lines could result in engine compartment venting. Not so good if you hit the trifecta of winter gas, a hot day and a stray spark.

 

Thanks man! Great info!

There's a lot more crap involved in removing all of this than I thought! lol.

What should I do about the PCV valve on the back of the valve cover? Also, what should I do if I want to replace the stock air cleaner with a performance one that doesn't need the oil bath that's connected to the top of the oil cap?

 

KAPOW! lol. Yeah I don't want that to happen to me.

As of right now the vent tube is non existent. I can only fill up my truck MAYBE halfway or it leaks right out of where the tube should be. Even when it's half full I have to be careful around corners or it spills out. Safety first!

 

You should keep the PCV. This will help keep the inside of the engine cleaner, avoiding buildup in the valve cover etc. The PCV should connect to manifold vacuum either on the carb or base of the carb. The oil filler cap should connect inside the aircleaner so clean air can be drawn in via that hose.

 

Oh ok cool! Thanks! I didn't remember that the PCV valve connected to the carb base before. As far as the oil filler cap goes though, if I replace the entire air filter assemble with an aftermarket one similar to this:

http://i.ytimg.com/vi/C6V4oBFtEN4/0.jpg

Then the air will be drawn in due to it's openness and the hose from the oil filler cap won't be necessary. Is this right? Or will it not work?

 

You can get an aftermarket oil cap that has a breather filter in it. They're about $8 at an autoparts store. And yeah, it'll eliminate the hose.

 

on my 82, i simple took the EGR spacer, disconnected all of the egr hose/components and plugged off everything cept the brake booster hose and timing advance hoses so you are running proper vacumm, removed the air pump, and gutted the cat and welded the air tube hole in the cat, you may simply have to tweak your idle air screw to compensate the the change in the engine's breathing i recieved a very noticable gain in all around performance and fuel mileage, mechanically speaking a smog system makes it much harder for an engine to perform all the way around, the original model 300 inline 6 from 1965-72 produced 170 hp and 283 foot pounds of tourque @ 1600 RPM, the 73 and later model was shockingly reduced to 101 hp and 223 foot pounds of tourque due to simply the smog system, that's 69 hp drop, it's sadly also why ford stopped using them in 1 ton and heavier trucks as they used to in 65-72

 

HP drop was due primarily to the change in the way HP was reported.

Search our "SAE Net" and "SAE Gross" HP and find out more.