Headers?
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Tuned
Joined: Feb 2025
Posts: 339
Likes: 222
Headers?
I am having to drop in a remanufactured long block to replace my current engine. The engine is a 302 EFI 5.0 out of a 1986 f150. The truck is a 1975 f100. While it's out I thought I would add some aftermarket headers. Any recommendations on some that will improve flow and still fit? I know this f100 has a narrower frame than the 1986 F150.
Fleet Mechanic
Joined: Mar 2013
Posts: 1,661
Likes: 1,062
From: Montana
Just my opinion, but unless you're doing a number of performance mods I wouldn't bother with headers. For the RPM these trucks will see, especially on a stock or mildly modified engine, they're not worth the headache of leaks, rusting through and fitment.
For a stock or mostly stock engines exhaust manifolds are just fine and much easier to work with.
For a stock or mostly stock engines exhaust manifolds are just fine and much easier to work with.
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Tuned
Joined: Feb 2025
Posts: 339
Likes: 222
Just my opinion, but unless you're doing a number of performance mods I wouldn't bother with headers. For the RPM these trucks will see, especially on a stock or mildly modified engine, they're not worth the headache of leaks, rusting through and fitment.
For a stock or mostly stock engines exhaust manifolds are just fine and much easier to work with.
For a stock or mostly stock engines exhaust manifolds are just fine and much easier to work with.
Fleet Mechanic
Joined: Mar 2013
Posts: 1,661
Likes: 1,062
From: Montana
If you already have the proper exhaust manifolds and your exhaust tubing is still in good shape, I would just use what you have. These trucks rarely see even 5000 RPM, more often they're in the 2500-3500 RPM range where velocity is far more important than overall flow. If you have too big of ports they can reduce velocity at lower RPM. This was a problem for example on the 351C engines paired with 4v heads. Below 3000 RPM air velocity was way down due to massive port sizes and the engines didn't run very well on the street. Get them on the track running above 5000 RPM and those heads performed very well.
For a stock 302, exhaust manifolds into some 2.25" dual exhaust, your choice of chamber muffler(s) or glass pack(s) would be sufficient. If doing 2 into 1, you might bump to 2.5" or maybe 3" pipe post merge.
For a stock 302, exhaust manifolds into some 2.25" dual exhaust, your choice of chamber muffler(s) or glass pack(s) would be sufficient. If doing 2 into 1, you might bump to 2.5" or maybe 3" pipe post merge.
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Tuned
Joined: Feb 2025
Posts: 339
Likes: 222
If you already have the proper exhaust manifolds and your exhaust tubing is still in good shape, I would just use what you have. These trucks rarely see even 5000 RPM, more often they're in the 2500-3500 RPM range where velocity is far more important than overall flow. If you have too big of ports they can reduce velocity at lower RPM. This was a problem for example on the 351C engines paired with 4v heads. Below 3000 RPM air velocity was way down due to massive port sizes and the engines didn't run very well on the street. Get them on the track running above 5000 RPM and those heads performed very well.
For a stock 302, exhaust manifolds into some 2.25" dual exhaust, your choice of chamber muffler(s) or glass pack(s) would be sufficient. If doing 2 into 1, you might bump to 2.5" or maybe 3" pipe post merge.
For a stock 302, exhaust manifolds into some 2.25" dual exhaust, your choice of chamber muffler(s) or glass pack(s) would be sufficient. If doing 2 into 1, you might bump to 2.5" or maybe 3" pipe post merge.
Cargo Master
Joined: Oct 2020
Posts: 2,636
Likes: 770
Headers will help torque across the board vs a manifold and with a long tube style particularly at low RPM. A good quality header with a thick flange installed using high temp RTV and no gaskets will not have troubles with leaks.
Moderator & parts slinger
Joined: Feb 2007
Posts: 50,098
Likes: 5,759
From: S/W Missouri, Polk county
Do you have the motor doner truck? Are you going to keep it EFI? If you are you are going to, have fun getting the 75 and the 86 to wire up and play good together. Electrnocialy and fuel, gauges, and some of there items can cause you some headache.
You are going to need ALOT of the 86 engine compartment wiring, main computer, or PCM, put 02 sensors in your exhaust. Address the fuel return line back to the 75 tank. Add as seperate elec fuel pump or get the 86 tank and reuse the EFI tank and sending unit? Seaking of that it is a 302 it is is stock, just go with exhaust manifolds.
You are going to need ALOT of the 86 engine compartment wiring, main computer, or PCM, put 02 sensors in your exhaust. Address the fuel return line back to the 75 tank. Add as seperate elec fuel pump or get the 86 tank and reuse the EFI tank and sending unit? Seaking of that it is a 302 it is is stock, just go with exhaust manifolds.
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Tuned
Joined: Feb 2025
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Do you have the motor doner truck? Are you going to keep it EFI? If you are you are going to, have fun getting the 75 and the 86 to wire up and play good together. Electrnocialy and fuel, gauges, and some of there items can cause you some headache.
You are going to need ALOT of the 86 engine compartment wiring, main computer, or PCM, put 02 sensors in your exhaust. Address the fuel return line back to the 75 tank. Add as seperate elec fuel pump or get the 86 tank and reuse the EFI tank and sending unit? Seaking of that it is a 302 it is is stock, just go with exhaust manifolds.
You are going to need ALOT of the 86 engine compartment wiring, main computer, or PCM, put 02 sensors in your exhaust. Address the fuel return line back to the 75 tank. Add as seperate elec fuel pump or get the 86 tank and reuse the EFI tank and sending unit? Seaking of that it is a 302 it is is stock, just go with exhaust manifolds.
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Moderator & parts slinger
Joined: Feb 2007
Posts: 50,098
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From: S/W Missouri, Polk county
I have a 76 Bronco crawler with sort of the same set up, and it is a vacume line/lot of other connections/wiring nightmare. I think they drank heavily when they did the swap. Stock output motor gets along just fine with exhaust manifolds.
Lead Driver
Joined: Oct 2018
Posts: 7,827
Likes: 2,339
Just keep the stock manifolds headers are for cars. the heat alone is reason enough not to have headers .
I have headers in my high boy only because it's a 428 CJ. stock FE manifolds just didn't seem right and the CJ car manifolds won't fit.
I have headers in my high boy only because it's a 428 CJ. stock FE manifolds just didn't seem right and the CJ car manifolds won't fit.
Cargo Master
Joined: Oct 2020
Posts: 2,636
Likes: 770
It really depends on what you're trying to do. I just looked at my notes when we tested this one time on the dyno. Using a 289 running from about 2700 to 6000rpm a set of 4 into 1 headers was worth 20lbs/ft and about 15 horsepower running through the same mufflers and pipes. This engine was very mild cam was 205 degrees at .050. and had stock heads and a set of HP 289 manifolds. I don't know how much the HP manifolds would be worth over a set of regular small block manifolds but I would assume about 15 horsepower.
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