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Exhaust manifold inline 300

 
  #1  
Old 03-14-2019, 05:46 AM
columbia1spring
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Exhaust manifold inline 300

1968 f250 in-line 300

I picked up this truck and it has a cracked exhaust manifold. I never tackled an in-line 6 and I need help with a few questions.
can I just remove the exhaust manifold and replace that or does the intake need to come off as well? I see plenty of aftermarket manifolds out there, is the fit good or should I hunt down an original? Any tips or advise?
thank you!
 
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Old 03-14-2019, 02:50 PM
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Here are a couple of idea's on intake & exhaust. The 300 motor picture shows an aftermarket Edelbrock DP intake with a pair of 300 EFI exhaust manifolds. Nice fit and should work well. The truck picture is my 1971 F250 300 6 with a hogged out 300 one barrel log manifold, 2v adapter with a 350 cfm Holley 2 barrel carb and split inline 6 cylinder headers. I plan on putting the EFI exhaust manifolds on my truck later this year in place of the headers as I like that look with my 2 1/2" dual exhaust. Header make changing starter a real PITA.

The motor I am building will have an Edelbrock C aftermarket intake with a 2V adapter and a Autolite 2100 or 2150 2v carb. The autolite 2100 /2150 are much easier to work and tune than the Holley.The 2100/2150 flow about 287 cfm. I use the truck for just driving around, no big loads and no towing.

 
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Old 03-14-2019, 03:46 PM
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Old 28's setup is sweet. In terms of your initial questions: The factory exhaust and intake manifolds are actually joined together where the intake sits on top of the exhaust under the carb. There's a couple long bolts down though the two pieces there that will almost certainly break if you try to remove them. My advice is remove the two components together. Remove carb, bolts holding manifold to head, hoses from the vac tree, exhaust studs, not much else to it. replacement gasket also comes as an intake/exhaust unit.
 
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Old 03-14-2019, 06:54 PM
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You will get a better power gain getting rid of the OEM log intake & exhaust. A Clifford or an offy 4v intake with a 4x2 adapter with 2100 / 2150 carbs is a good running setup for a basic stock motor. Others want more carb and like to run 400-600 cfm 4v carbs. A lot depends on how much you want to do on the new toy? The 300 EFI exhaust manifolds & a full dual exhaust will be a great bang for your buck.
 

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