I'm about to order up my headers and new exhaust. My question is are the exhaust and intake manifolds able to be separated? I have an 81 F150 with the 300. The reson I ask is when I swapped the head the manifolds came off as one piece, I dont want to order my headers and realize I need a new intake as well. Any input is appreciated!

 

Yup, there's only 3 bolts holding them together. They come apart very easily.

Although, with headers, a new four barrel intake and a four barrel carb wouldn't hurt either.

 

Thanks! Now I can order my parts!

hahahahah I considered it, but my budget only allows for a BA exhaust, so I think I can settle witht that! lol
again, thanks AbandonedBronco!

 

Anytime.

And no worries, I felt an amazing difference upgrading my exhaust to a single 2.5" with the dual EFI 300 exhaust manifolds, and this was with the 1bbl. You'll really notice it with headers and a new exhaust.

Have you looked into the "extras" you may need to do when switching to headers? The stock exhaust and intake were bolted together to keep the carb warm during operation (since it was out away from the engine, unlike a V8). It's generally a good idea to run coolant heat over to the carb to keep it warm once removing this. Also, if it's an issue, all of the emissions equipment on the 81 ties into the exhaust manifold in one way or another. Lastly, you may need to do a little tuning on the carb since it's designed to run with emissions equipment.

Just a little heads up since I just went through it all last fall and it's still fresh in my mind. Have fun!

 

Other than the coolant over the Carb, what extras are needed to install a header? Also, when running coolant over the carb, can I just run an extra line from my radiotor hose over the carb? Or is there a more efficiant way of getting this done?

 

I just saw the pictures of the Carb coolant, it looks amazing! I know that there are many many many threads about exhaust set up but since I'm posting, I was looking at running the headers with cat back exit before the rear wheels, AbandonedBronco, would you recommend mufflers? or longer tubing?

 

The coolant to the carb is the big one. You'll feel a performance difference without it because it won't have the heat to atomize the fuel properly.

I had this plate made using the stock gasket as a template. (As you can see in the pic, it was a little off and I had to grind the bolt holes a little wider.) The holes in the center are drilled for pipe fittings.



Went to the plumbing store and spent $10 getting some pipes. You want them long so you can keep them away from the heat of the exhaust, especially with headers, or the rubber'll keep cracking. Since you have headers, you'll want them longer than the ones I have.



And yeah, I just spliced into the hose that ran over to the heater core and it worked great. The main thing to do is to clean out the inside of the intake where the exhaust bolted to it to get all that carbon out of there. If not, your coolant will clean it out for you and will fill your coolant system up with carbon junk.




Other than that, if you're not worried about emissions, just block off the EGR.
If yours is set up like mine (which it probably is since they're both 81's), you'll have to either make a custom gasket to block off where the smog pump went into the exhaust. If not, this coolant hookup will blow coolant up that opening and out. You can either do that, or just get a plug at the plumbing store and stick it into where the smog pump goes into the EGR spacer.

That being said, I passed local emissions without the EGR valve or the smog pump hooked up. A 3-way cat took care of everything.

 

I guess it's all in what you want. The 300 will put out some serious noise without mufflers. I just had the EGR plug out of one of the EFI manifolds on the way to the exhaust shop and it sounded like a tractor. I have to admit, I did enjoy the loud sound for the short trip.

Since you have an F150, you'll have plenty of length, and before the tires would be pretty sweet.

 

Wow! those pictures help a ton! One question, the coolant isnt flowing freely inside the intake is it?

 

In the intake, there's a hollow chamber that's wraps around where the carb sits. It's completely sealed off from the fuel/air part of the intake. The coolant goes in, floods the chamber, and keeps everything nice and toasty. The only exit out of the chamber is where the smog pump goes in at the top, which is why that needs to be sealed with a gasket, or sealed up further where the smog pump went into the EGR spacer (easier, but requires leaving the EGR spacer in place.)

In the bottom picture, you can see the "dent" in the gasket just to the right of the carb intake opening. That's the hole the smog pump went in to. I made a gasket, but the pressure ripped it, so I put the plug in place in the EGR spacer.

 

Thanks AbandonedBronco! I would have never known to do that mod without your help. Besides the "toasty Carb" is there anything else I should keep in mind when swapping in headers?

 

Yeah, that took me a while to figure out. I kept getting coolant all over the place and couldn't figure out where it was coming from. Kept pulling the plate off, sealing it back up, tighter, and tighter, and tighter, more and more sealant, and it kept leaking. I was about to pull my hair out. Finally noticed it was leaking out of my smog inlet (still had the original equipment bolted up, so it slowed the leak). Figured I'd save you the hair pulling part.

I think other than that, that's about it. The rest is just emissions stuff.
The only other thing is there's a metal heat shield that wraps around the stock exhaust and then ports the heat up into the air intake for the air filter. This helps with warming up the engine faster on cold mornings. Since it's designed to hook up to the stock exhaust, you won't be able to use it unless you modify it. If you're not worried about it, it's no big deal (I didn't bother). You'd probably be better off pulling that entire system off anyway and putting a fully open air filter. The stock one is very restrictive.

 

Thanks for all the help! I just ordered my parts and they should be here in a week or so! Ill let you know when I get it all set up!

 

Awesome. Glad I was able to help. Have fun, you'll notice a real difference.

 

Abandoned Bronco, quick question for you, since you took off your EGR spacer did you just tune the carb to run a bit richer to make up for the lack of an EGR? I'm looking to run EFI manifolds on my 250 soon but since I tow and work with it alot I want to avoid a pinging noise from removing the EGR.