Manifold question
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Freshman User
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Manifold question
300 I-6
headers
dual exhaust
what is meant by efi manifolds and why are they better than stock? Is it just the exhaust manifold that I should replace, or is there an efi manifold for the intake as well? I have been planning on doing the popular offy dual port with a Holley 390. I just haven't ordered the parts because I don't know what miscellaneous gaskets, throttle linkage, or any other parts I need to get. I do know I will have to get another air filter and housing once the 4bbl is on.
Thanks, Sam
headers
dual exhaust
what is meant by efi manifolds and why are they better than stock? Is it just the exhaust manifold that I should replace, or is there an efi manifold for the intake as well? I have been planning on doing the popular offy dual port with a Holley 390. I just haven't ordered the parts because I don't know what miscellaneous gaskets, throttle linkage, or any other parts I need to get. I do know I will have to get another air filter and housing once the 4bbl is on.
Thanks, Sam
Elder User
Joined: Sep 2003
Posts: 926
Likes: 3
From: SE, Michigan
From the sounds of it Im guessing you have a 1977 truck with the 300 in it. Is it automatic or manual trans, 4x2 or 4x4? When I did this swap/rebuild on my 82 F100 I went with the efi exhaust manifolds off of the 87-96 300 engine. I also used the offenhauser dual port intake with a holley 390 cfm 4bbl turned with the primaries closest to the engine. The efi exhaust manifolds are different in that they are two separate pieces with two 1 3/4 inch openings rather than the carburated engines exhaust manifold that has all 6 cylinder dumping into one manifold with a single 1 3/4 inch opening. They flow much better than the standard carburated exhaust manifolds. And a picture of mine:
https://www.ford-trucks.com/user_gal...122229&width=0
If you already have headers then they are even better. I finally got my holley 390 to run great and I love it. For the throttle bracket I made one to attach my stock bracket to the offenhauser intake. Check my gallery for the pictures and a drawing. Im not sure how the 1970's truck have the stock throttle linkage but my 82's linkage hooked up just fine.
https://www.ford-trucks.com/user_gal...122229&width=0
If you already have headers then they are even better. I finally got my holley 390 to run great and I love it. For the throttle bracket I made one to attach my stock bracket to the offenhauser intake. Check my gallery for the pictures and a drawing. Im not sure how the 1970's truck have the stock throttle linkage but my 82's linkage hooked up just fine.
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Freshman User
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Thanks for the feedback. Understanding that I have very little mechanical experience, here is my next batch of questions:
my headers make up for the exhaust manifold(s), and I don't have to worry about it, correct?
-how difficult was it to time and adjust the new set up after installed?
-what are the primaries on the 390 and why do they need to be turned toward the engine?
-I suppose that I am going to need a new air cleaner and housing, 1982fordf100, you have a 10''. is that what I am going to need?
-is there any break-in process for a new carburetor and/or intake manifold?
my headers make up for the exhaust manifold(s), and I don't have to worry about it, correct?
-how difficult was it to time and adjust the new set up after installed?
-what are the primaries on the 390 and why do they need to be turned toward the engine?
-I suppose that I am going to need a new air cleaner and housing, 1982fordf100, you have a 10''. is that what I am going to need?
-is there any break-in process for a new carburetor and/or intake manifold?
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yeah, he had his whites on and had all that shiny stuff and i was just a dumb Lcpl. Bad thing is that I was at Coronado and he was the asst training chief for BUDS.
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Elder User
Joined: Sep 2003
Posts: 926
Likes: 3
From: SE, Michigan
Originally Posted by 77'Sam
Thanks for the feedback. Understanding that I have very little mechanical experience, here is my next batch of questions:
my headers make up for the exhaust manifold(s), and I don't have to worry about it, correct?
-how difficult was it to time and adjust the new set up after installed?
-what are the primaries on the 390 and why do they need to be turned toward the engine?
-I suppose that I am going to need a new air cleaner and housing, 1982fordf100, you have a 10''. is that what I am going to need?
-is there any break-in process for a new carburetor and/or intake manifold?
my headers make up for the exhaust manifold(s), and I don't have to worry about it, correct?
-how difficult was it to time and adjust the new set up after installed?
-what are the primaries on the 390 and why do they need to be turned toward the engine?
-I suppose that I am going to need a new air cleaner and housing, 1982fordf100, you have a 10''. is that what I am going to need?
-is there any break-in process for a new carburetor and/or intake manifold?
2. Your carb is probably going to need to be rejetted.
3. Primaries are the side of the carb that the engine will feed off of during normal driving. Its the side that has the choke on it.
4. Yes you will need any 4 barrel air cleaner that will clear the heater core.
5. No break in procedure.
I really can't tell you everything there is to know about tuning a carb or your particular truck. Everyones is going to be different. The best thing to do is read through alot of the post on here and search. I had to do alot of reading to educate myself. Read different car magazines as well. I spent at least two years figuring out what I would need before I bought all of my parts and did the rebuild and swap.
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Joined: Jun 2003
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From: Lancaster, SC
Pulling the primary float bowl, remove the old jet, install the new jet, reinstall the float bowl. You will also need to know how to read your spark plugs. ther is also a tool that you look through and adjust your jetting according to the color of the spark.
Your Holley will be pretty close out of the box.
This will be a great learning experience for you. There's a lot of info on these truck forums. the "search" feature will be your best friend. I use it all the time and can usually find my answers there. If I can't, then folks are quick to reply on the forums. This forum and the "other forum" I saw you on are the two best resources I've found for these trucks.
Your Holley will be pretty close out of the box.
This will be a great learning experience for you. There's a lot of info on these truck forums. the "search" feature will be your best friend. I use it all the time and can usually find my answers there. If I can't, then folks are quick to reply on the forums. This forum and the "other forum" I saw you on are the two best resources I've found for these trucks.