Manifold/Header
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From: Dayton, Ohio
Manifold/Header
What are the pros and cons of using the dual exhaust manifold, to using headers? Also, what is the difference in using a single outlet header to a dual outlet header on the 300?
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From: Oregon-Take me wheeling..
well, i talked to a few muffler shops in my home town, and they told me that if go duel 3" i will lose low end torque, duw to thte fact that the 300 does not rev high, all there is is low end torque. the best set up, i was told, if you are keeping the stock duel outlet manifold, it to keep the first cat, for legallity issues, remove the second and run a single 3" for the forst cat back
callen
callen
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From: Corvallis oregon
I think that it depends on what your motor is built for. In stock condition I would recommend the dual outle manifold. The dual outlet header from hedman flows very well but it would be overkill for a stock motor. I don't put headers on trucks unless I think I have to. The single outle manifold is fine if that is what you have and you haven't done anything else to the motor.
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You will not "Lose low end torque" with a set of dual headers if you jet the carb correctly for the increased flow. I put a set of JC Whitney dual headers on my 74 F-350 w/300-6 and had to open up the main jet as it went lean. I didn't know about the EFI dual manifolds at that time, I would prefer that setup for mainenance reasons as headers can be a pain, but so far mine have been ok. This is an otherwise totally stock engine and the EFI manifolds will perform just as well with less hassles in the long run.
Joe
Joe
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From: Broken Arrow, OK
I went from EFI manifolds to Hedman headers and there is a night and day difference. I havn't had any problems with leaks at the cylinder head flange, and the problems at the collectors went away after investing $10 in copper collector gaskets. If you do a search with my username and headers you should find all the things you have to do to make them work. After the PCM adjusted I gained 7 mph and about 2 seconds in the 1/4 miles just from the headers. They are a pain to install, but not the maintenance nightmare they are on most engines. They don't usually leak at the cylinder head because the flanges must be extra thick to properly align with the intake manifold.
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Silver Streak - Or anyone else - I will be having to replace my stock exhaust manifold because of leaks. Would you recommend getting the headers that you mentioned above (about how much were they anyhow) or stick with stock replacement.
I am mostly worried about conserving towing ability or improving it. Will that happen with the headers?
Also, I have never done anything but replace the muffler and tailpipe in dealing with exhaust. Is it complicated to rework the system to fit the existing exhaust to the headers?
Thanks for the help.
I am mostly worried about conserving towing ability or improving it. Will that happen with the headers?
Also, I have never done anything but replace the muffler and tailpipe in dealing with exhaust. Is it complicated to rework the system to fit the existing exhaust to the headers?
Thanks for the help.
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From: Oregon-Take me wheeling..
silver streak- im interested too, where did you get your headers, what catalog, website etc.? are they dual outlet? are you running any cats? do you have dual exhaust or take the two into one? im very interested
Idiomaticman
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From: Broken Arrow, OK
I got them from www.summitracing.com for $119. I think they are $135 now. They are dual outlet. I built my Y pipe as two 2.25" pipes running into a single 3". No cats. I don't have any dyno numbers for my truck, but it now makes over 270 ft-lbs at the wheels at 2000 rpm, and is over 260 from 1500 to 3000. That's more at the wheels than the factory claims at the flywheel. I've never had any problems towing anything. With EFI you lose the EGR system and AIR system when the headers go on, but both could be kept if you wanted to put the work in. The alternator bracket also requires a significant notch to clear the header as well as spacers installed between it and the block to clear the #1 tube.
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Silver Streak - Thanks for the info. I am not afraid to try anything, but I dont have much help around here. I was wondering though what you mean by losing the EGR and AIR systems. I am very familiar with the parts of the EGR system ( I did a lot of work on it this past summer) but what is the AIR system? Is it the air pump?
Also, what would have to be done to save those systems and do they need to be saved to pass emissions? I think I could come up with a hundred questions here.
Does the computer get messed up without the systems or with the exhaust system changed?
Again, a thousand thanks for your help. Its nice to have a place to ask some question. I dont have any good local shops around me that sell parts, just a few of the chains and it seems that you dont always get the right answer.
Have a good holiday
Also, what would have to be done to save those systems and do they need to be saved to pass emissions? I think I could come up with a hundred questions here.
Does the computer get messed up without the systems or with the exhaust system changed?
Again, a thousand thanks for your help. Its nice to have a place to ask some question. I dont have any good local shops around me that sell parts, just a few of the chains and it seems that you dont always get the right answer.
Have a good holiday
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From: Broken Arrow, OK
If you have to pass emmissions you don't want to install headers. The EGR and AIR systems are needed for emmissions testing. The AIR system injects air into the exhaust to finish burning the hydrocarbons that weren't burned in the cylinder and also helps the catalytic converters light off.
The computer definitely knows something has changed when the headers are installed. It will probably run horribly for about 100-150 miles after the install, but will adjust and run fine.
The computer definitely knows something has changed when the headers are installed. It will probably run horribly for about 100-150 miles after the install, but will adjust and run fine.
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From: Dayton, Ohio
Thanks for all the info! Luckily, my '69 300 is going into a '50...So no emmissions needed. I'm not looking for something to rip pavement with, just enough power for reasonable acceleration. Sounds like I should go with the dual manifold. Once again, thanks!
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From: Eveleth, MN
Might be time to replace the EFI manifolds with the spare headers I have in the garage. should givre my 89' a good bump. I have no Idea what brand they are and they have 1 1/2 primary's. The hookers on my 83' have 1 5/8 primary.
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