Headers vs stock 4V exhaust manifolds

Just curious as to the pro's and cons. I'm getting ready to put closed chambered 4V heads back on my 71 M code 351 which currently has 2V heads on it (long story). Wondering if 4V exhaust manifolds for the 4V heads are the way to go to keep it original or do headers really make that much difference on compared to the 4V manifolds.

LOL here we go again.

Just curious as to the pro's and cons. I'm getting ready to put closed chambered 4V heads back on my 71 M code 351 which currently has 2V heads on it (long story). Wondering if 4V exhaust manifolds for the 4V heads are the way to go to keep it original or do headers really make that much difference on compared to the 4V manifolds.

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Pro's of headers ...will give you a boost in HP...one of the best bang for your buck for easy 30+ hp gain or more....The stock ones realy restrict the flow...They sounds good if you like your stang to rumble...you get better gas milage..your motor can breath better.

Con's...They can leak...newer headers dont have as much issues...but i had a set that did leak back in the day...i seen plenty of new ones never leak.....All counts if you get the right gastket...Copper gaskets are the best i seen....You need to check once and a great while see if they are loose.....headers can rust out and look kinda ruff...unless you get the ceramic coated ones...but can always be repainted and look ok.

Stock...Pro's...They are tuff....Usualy dont leak....they are nice and quite if you dont like your stang to rumble.

Con's...Restrict flow.

If its up too me...Every car would have headers...hehe..They are worth the hassle too me...and i like them having a bit of grunt sound....but they are not for everyone thats for sure.

WOO HOO.

I have been waiting for this. Let us compare, shall we:

Wolverine's Ultimate Header/Exhaust Manifold Diatribe.

NOISE LEVEL: Headers are louder outside, inside and under the hood. Manifolds can be made quiet, though I doubt they can ever be as loud as headers...but close.

HEAT LEVEL: Headers are hotter under the hood. No comparison there.

Solution: Header coatings are available at $200 or more, and are SUPPOSED to offer less sound and less heat. But I have not done a scientific comparison. Newly coated headers must be broken in. No manufacturer recommends them to be broken in on the first start up/break in of the motor. Of course people have not followed this recommendation and have both done so with/without damage to the headers. Your mileage may vary.

ENGINE LIFE: Due to the thermodynamics of mass and heat, exhaust manifolds "should" carry heat away from your motor more effectively then headers, thereby increasing the longevity of your engine. This is especially important for the EXHAUST VALVES which do not see the cooling power of the evaporation process the intake valves see.(Physics lesson via my 12th grade Physics teacher, Mr. Edward Van de Hayden, RIP...evaporation is a cooling process) I say should increase engine life because I have known guys that have run headers for 100k miles in NON SALT ROAD STATES without a motor issue.

(It used to be reported that back pressure from the exhaust manifolds was necessary to allow the combustion air to stay in the chamber longer to allow the exhaust valve heat to transfer to the air. That is no longer believed. The most important factor is having the cylinder head exhaust seats match the valves.)

MAINTENANCE: Some guys who can't get paint to dry have to tighten their headers every 20k miles. Others never tighten the headers. The header bolts are a pain to get to.

They make lots of bolts that are supposed to never loosen. I used HEX HEAD bolts. Exhaust manifolds stay tight forever.

DRIVE HEIGHT-GROUND CLEARANCE: Most headers sit lower to the ground and are hazardous on speed bumps. Some headers sit tight to the underbody and typically cost an arm and a leg.

How much did you pay for those mufflers? And you don't care about ground clearance? When was the last time you drove on the freeway and DIDN'T see a mattress.

Exhaust manifolds don't have this issue unless you have a bad exhaust man.

FITMENT: We have guys here with same cars, same motors, same accessories, same headers reporting different installation issues. Some have no issues. Others do. If you want headers, travel to someone who has RECENTLY installed headers(Header design can change at the whim of the manufacturer) and take a look see.

COST: All I can say is I have been able to get 4V Exhaust Manifolds for my 73 351C for $200, passenger and driver. Driver is harder to find. New headers start at $200. When I priced a pair of LONG, high road clearance, coated headers I was at $800...and that did not include shipping.

SHORTY VS LONG TUBE HEADERS: In order to avoid the clearance issue, I investigated shorty headers. I went onto no less than 5 Mustang forums asking if anyone had installed shorty headers on their 71-73 351C 4V Mustang. Not a single response. I then went to the shorty header mfr sites. I asked the mfr to forward my email to their most recent customer who installed their headers onto a 71-73 Mustang 351C 4v. No response.

So...you can be #1.

PERFORMANCE: Controversial. Assuming you have not built a high performance motor, under 5k RPMS you will not see a measurable improvement in headers. You will hear more noise to think you are accelerating faster. But there will be no significant back pressure with the exhaust manifolds at that point. If you drive above 6500 RPM, then you will see some improvements, maybe 5% with an increase in percentage with an increase in RPM. At 7500, maybe 7.5%. If you have built your motor, significantly built your motor, than why would you restrict the exhaust with an exhaust manifold, or mufflers for that matter.

There, was that so hard. And nothing here should be controversial...except the performance.

LOL here we go again.

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X2 Roy! but I cannot resist adding my nickles worth.

Good points James. I firmly beleive unless your goal is MAXIMUM performance there is not enough there when you slap a pair of street mufflers behind them.

It has taken me many years and many sets of headers to come to this conclusion.

To answer your original question Jim... IMHO Nope!

You could end up spending more on a set of manifolds than you would on a set of headers...

Also, long tube headers help torque, through scavenging. They don't just improve top end power.

If you go hookers, use the hooker gaskets to get a good seal. Use stage 8 locking bolts (brand name, pain to install) and they won't leak.

Don't buy used headers from ebay.

This is a Mopar test but I think the points they make are valid. Chuck http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/viewall.html

This is a Mopar test but I think the points they make are valid. Chuck http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/viewall.html

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Big torque difference:exclamation:

This is a Mopar test but I think the points they make are valid. Chuck http://www.moparmusclemagazine.com/techarticles/mopp_0106_manifolds_vs_headers/viewall.html

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Big torque difference:exclamation:

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"First, we bolted on a set of stock iron 440 Magnum manifolds. These had a nicely swept design, and except for the rare Max Wedge cast-iron headers, were about as good as it got in factory iron"<~~Makes me wonder how much we gain from headers...I heard our clevelands have very restrictive iron headers...i heared a 40hp gain or more...But i usualy state only 30hp or more...so people dont expect too much..but wow.

All excellant advise and very much appreciated. My take on it is if I already had the 4V manifolds for the 4V heads, I would go ahead and use them...but since I don't, I might as well buy headers. Hooker competition headers 4V?

Jim

The bigger the cam overlap/lift/der the bigger the difference in headers.

IF you do, get them HPC/Jet Hot Coated and buy HOOKER headers and if running a big cam SUPER COMP headers.

Check out PERCY's brand of gaskets too.I like the Fel-PRO brand but the "blue" gaskets don't fit the 4v port/Super Comps well.

Jegs's below....

Percy's 66052

ALUM EXH FORD 351C 4V

Ford

Ford

Item# 760-66052

All excellant advise and very much appreciated. My take on it is if I already had the 4V manifolds for the 4V heads, I would go ahead and use them...but since I don't, I might as well buy headers. Hooker competition headers 4V?

Jim

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I have run the Super Comps since 1992. I had them HPC coated.

The welded collector is far superior to the sliding style in my opinion.

Most gasket sets you can put the 1st and last bolts into the head and slide the gasket in.

Much better than trying to hold them up w/port plates(?) and start a bolt.

The tubes are 2" on the Super Comps with 3.5" collector so beware.

The standard comp units would be best in some cases.

I got no experience with difference in performance as the headers came with the rebuilt of my original 302. At the same time the stock intake, carb and cam hot swapped for Edelbrock performers. So I got no idea what the headers did for performance.

One thing I do know is that ground clearance has become a serious issue now that the car has been lowered. Before that not so much but meanwhile the tubes are flat at the bottom instead of round, because they've hit the ground so many times.

On the other hand I think that most cars will never come as low as mine, so you might pull it off.

That is why I'm gonna put shorties on after I get back from my vacation. Complete with a stock Mach1 exhaust, except I'm gonna keep the Edelbrock mufflers.

If I notice any difference, you guys are gonna be the first to know about it.

SHORTY VS LONG TUBE HEADERS: In order to avoid the clearance issue, I investigated shorty headers. I went onto no less than 5 Mustang forums asking if anyone had installed shorty headers on their 71-73 351C 4V Mustang. Not a single response. I then went to the shorty header mfr sites. I asked the mfr to forward my email to their most recent customer who installed their headers onto a 71-73 Mustang 351C 4v. No response.

So...you can be #1.

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Good points Wolverine and I'm also happy this topic came up,

I have been concidering shortys for a 351c-4v but can't find a definitive answer either. Are there any power gains over the stock 4v manifolds?

Most guys probably put them on when they had the engine built, so they don't really know.

I read somewhere that a "friend of a friend" dynoed the stock 4v manifold VS

shorty header and did NOT see much power gain with the shorty. They did not say what brand of header they tried. They also tried the 2v manifold vs shorty and said there was a significant power gain with the shorty. They did not say if they bolted on the 2v heads too (I would think there would be a serious port mismatch with the 4v heads).

They went on to conclude that the stock 4v manifold was actually pretty good. YMMV

They also said that long tubes do increase power over the stock 4v manifold. (But then long tubes have all those fitment problems and low road clearance.)

OTOH Sanderson (a mfg of quality shorty headers) says on their website that their shortys make significant

power gains over the stockers, they say they are actually BETTER than long tubes for the street, but their test mule was a BB chevy.

Conflicting, to say the least.

So my decision is to skip the headers. Had considered getting a set but with

less ground clearance and heat issues plus mediocre performance improvement, I'll

opt out. The engine is a newly rebuilt stock 351C 4V quench with a cam, 770 Holley,

toploader and 3.50 posi.

mike

I' m with you Mike, not worth it.

I'd like to see the results of the Mopar test with a couple of different mufflers.

I don't think Jim will have ground clearance issues. His car is at least stock height. It makes mine look lowered with original springs.

The newer hookers fit so much better...They fit waaaaay better than headers from just 10 years ago...They dont hardly leak like the old ones...They have lisned to the complaints over the years and fixed alot of these issues. ...they fit much tighter now days...and they are proven over and over to be one of the best bangs for you buck for easy quick horse power...Its not easy to get a quick 30hp + gain with out major mods......been test on the track ,and plenty of dyno test across the board...They will give your motor more HP and TQ...Thats a fact ..and if they dont...Sue them for lieing...which im sure they would of already been sued for it by all the racers across the board by now..lol

A little something to ponder.

Not Cleveland, but FE:

http://www.fordfe.info/Exhaust/Exhaust.htm

And then there's a stock 302:

http://www.mustangandfords.com/techarticles/mufp_0607_ford_mustang_performance_exhaust/viewall.html

I remember reading a magazine years ago that compared the SBF logs to K-code to headers like above, and came up with nearly a 90hp increase from K-code to headers. Can't find the article, but thought it was horse hockey to say the least.

My opinion, FWIW, is do what you need to do, especially on a street engine. I, for one, am going to use cast manifolds on my 460 if I end up using it.

- The issue of (reported poor header) fit for the application is first and foremost.

- Ground clearance... very necessary in pothole ridden Southwest PA.

- Piss poor answers from "the" 2 popular mid-length header manufacturers contacted.

- Ridiculous cost of all headers for the application.

- I have cast manifolds in stock.

Back in the early '80's, a guy at the track that I befriended ran a bone stock '68-70ish suicide door/hideaway headlight, Brontosaurus sized Thunderbird . Can't remember if it was a 429 or 460, but who cares. He only removed the air cleaner, interior and trunk junk and dialed in @12.99 every Sunday, on worn out Goodyear Eagle NCT tires. I'll never forget that.

I repeat: bone stock.

What a kick that was to watch.

My Dad used to refer to exhaust manifolds on a street performance engine as "similar to jogging with a sweatsock in your mouth".

Dad had a cool sense of humor

It's all in what you're after.