my 71 xlt has a 390 with cast iron manifolds that leak and someone has already broken one or two of the bolts off trying to remove them im going to stop the leaks but should i replace manifolds with headers or put the manifolds back on the truck.the truck will not be used to much for pulling mostly daily driveing but i do like to blow past a chevy every now and then so the increased performance of the headers is something that i wouldnt mind any suggestions

thanks jeff

 

Headers are a great upgrade for the 390 as the stock exhaust is a poor design. The main downsides to the headers are extra heat to the starter and installing the starter.

You can get a heatshield for the starter for about $20 and you should do something to protect it from the heat.

My headers were off by about 1/8" so I had to elongate the holes a bit for a proper fit and had to cut the gaskets as they didn't match properly either.

I'd look into some coating of some type to make them last longer as well.

Hookers are one of the best but are costly, I've heard good about some others in the $100 range, I think www.jegs.com has them.

Overall, the headers are more work and cause more noise but I think they are worth it.

 

Jeff, If you gotta have em, just can't live with out them, then ONLY go with shorties. I spent 4 hours of straining, grunting, groaning, and cussing a set of long tubes changing out a started yesterday. You should be able to change out the starter on a FE in 20 min.

After going there and doing that, absolutely run duals, forget the headers unless you are running the engine 5000 rpm and over, regardless of what the hot rodders say.
IMHO of course
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John

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In the cool still quiet of night, you can hear chevies rusting away.

 

Headers will increase the torque of the engine starting at 2000 RPM. After that it just gets better. The Hooker headers fit the stock truck heads pretty good. If you have Edelbrock heads or CJ heads go to FPA. They can make a set that will fit.

Changing the starter can be a pain with the long tube headers, but they make better power than the shorty header design. Maybe have the starter rebuilt at the time of the header install?

Get the ceramic coated version, they lower the heat in the engine compartment and stay looking good.

 

Is,
I've got a F150 351M. I've got full length header Headmen headers. I can't say enough about the power/torque increase. I've maintained everything else stock and its is a huge HP gain.
Now about the rest. They are loud. They are hard on the starter. Get a heat shield! They have bolt on collectors that break the gasket two to three times a year. They are woth it to me maybe not to you.
I've got a 76 F100 302. I've got Hookers on it and I saw the largest gains form my exhaust system. Not the intake, not the carb, maybe the cam.
I like manifolds but only on my mom's car.
Good Luck, Have Fun,
KingFisher

 

Buy ceramic coated headers or don't waste your time and money. The ceramic's keep all the heat inside the exhaust so your starter won't fry. They are guaranteed for life and they look a lot cooler. Speaking of cool, your engine compartment and cab will thank you because the heat is carried to the exhaust. They will never rust and they don't need to be painted.

 

I would also recomend a set of headers, and to make sure you get a good ceramic coating on them. I don't think the hookers are all that great though. For a truck, you want a good set of tri-y headers because this will maximize your torque and lower end horsepower, with only a small sacrifice to top end ponies as compared to the full length type. Headers can be a nightmare, unless you get a great brand to begin with. For my money, "Stans Headers" are the best out there.

 

Negative Nellie here!
Headers are a "Pie in the Sky" that can never out live the stock manifolds.
Nobody that sells headers will show you a Dyno Print that shows any kind of Torque or Horspower gain on a Stock engine.

The stock manifolds do some really neat engineering things for your engine that Headers cant do. Heat retention, Scavenging, etc etc.
The Theory that the Flow of the exhaust gasses will move easier through the smoothly formed headers is correct. It just aint enough of a difference to justify the cost and the shorter lifetime of the Headers.

Those broken manifold bolts are part of the "Fun" of it all. I've had to do three of my 460 bolts. Headers or manifolds or the very special Manifold bolts dont have anything to do with the end result. It's the environment they live in that causes the bolts to sieze.

 

You guys help make my point "Headers will increase the torque of the engine starting at 2000 RPM." 2000 rpm is entering the crusing range, depending on gearing 2200-2800 rpms.

"I can't say enough about the power/torque increase. I've maintained everything else stock and its is a huge HP gain." I really think the louder, and different sound is just testosterone flowing, You just like it better.

Guys I have two trucks, both automatics. One has a grungy looking ol FE in it 2 barrel, regular fire, stock manifolds with duals, and the other fresh less than 10,000 miles, Edlebrock carb, intake, cam, Mallory Unilite fire power, Hooker Supercomp headers, and .25 difference in the rear gear.

I have something to compare, IT JUST AINT SO.

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In the cool still quiet of night, you can hear chevies rusting away.

 

I just bought a cheap set of headers for my F100 360 (Dynomax from JEG's). Haven't even put them in yet.

The driver side manifold has that butterfly valve on it to help the engine warm up, however it is stuck pretty much in the closed position. That was the decision maker for me to get the headers. After I install the headers I will probably clean up the manifolds and see about removing the stuck valve (and broken studs). That way if I don't like the headers I can always go back to the cast manifold.

Has anyone out there used one of the header wrap insulating kits?

Mark

 

Mark, Fix that Exhaust valve, right away, before it burns the Exhaust valves on the two center cylinders on the Drivers side. Take the Heades back and use the money to buy your Wife something she'd like.

 

The stock log exhaust manifolds do not do anything for scavenging. Ceramic coated headers last a long time and do retain the heat. Do they last as long as stock exhaust manifolds? Probably not. But with a lifetime warrenty do I care? No.

I've personally installed headers on an inline 6, a V6, 2 different small blocks, and the 390 in my truck. The seat of the pants feel tells me there is a difference. However the only scientific way would be to do before and after dyno runs. Thats not very practical. One other way is running Desktop dyno which shows is significant increase in the 2000-3000 RPM range. They do work.

If you want headers get a good quality set and get them ceramic coated.

Reggie

 

[updated:LAST EDITED ON 20-Nov-01 AT 02:59 PM (EST)]
>Headers are a "Pie in the Sky" that can never out live the
>stock manifolds.
>Nobody that sells headers will show you a Dyno Print that
>shows any kind of Torque or Horspower gain on a Stock
>engine.
>
>The stock manifolds do some really neat engineering things
>for your engine that Headers cant do. Heat retention,
>Scavenging, etc etc.

The stock exhaust manifold on your 460 must be one heck of allot better than the stock exhaust log we are talking about on his FE here. I'm not trying to pick a fight, but this is one of the more ridiculous statements I've heard. Sure, John is right, for a stock daily driver headers don't make sense. But if you want increased horse and torque you can get that with headers *properly matched to your application* I put that in asteriks because with the wrong set of headers you can lose torque and horse in the lower end...where your truck needs it most. I've built, raced and dynoed all sort of combinations...no stock exhuast manifolds can hold a candle to a high quality header matched to your engine configuration. Not by a mile.

 

Seth, Now we are starting to make some headway. Most of the guys asking questions here are running daily drivers, that may or may not hit 4500-5000 rpms twice every 6 months. I see in your sig. file that you list a "built 428CJ" in your truck. That my friend aint no daily driver truck, even if that is what you do with it. I wont argue that there is a serious air jamb on the passenger side manifold on a FE engine. Just adding dual exhaust to an engine that has pushed all of it's gases out one pipe is a big improvement. Every race car engine that I have ever seen has headers, and thay all operate over 4000 rpms not under. Yes the maxed out built engine can improve with headers, but I will not back off of the idea that adding headers to the normal pickup truck make no big increase. You gotta prove it to me. You can find my shop right off I-85 exit 175 in North Carolina if you want to show me. :-)
You will not recover anyway close to the $600-800.00 for adding headers tied up, 4 barrel intake and carb to a daily driver pickup truck.
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In the cool still quiet of night, you can hear chevies rusting away.

 

Well John, I'm not about to argue with you that a vanilla stock engine will see large gains from headers alone. Although, a stock engine would still see gains all the way down into the low end with a top dollar set of tri-ys (such as Stans). Enough to recoup the cost? I think thats a judgement call. With my engine it builds gobs of horse and torque from roughly 2 grand up, and no, its not a daily driver. At 7 mpg it would soon bankrupt me. Although, if you'd like to pay for the gas it would take to get from Oregon to Carolina I would still be happy to drag ya Hmmm, thats an idea...FTE meets...