IMCO muffler questions

So I continue exploring my 1971 Mach 1 that I bought couple months ago. The mufflers are IMCO T-949. I never heard of IMCO before. Do you know anything about these? Are they good mufflers? Right now I have the stock manifold, but I am planing on installing Hooker headers this winter. Will these mufflers hold? Is it a good combination?

IMCO is a house brand that a lot of exhaust shops use. They are basically knock offs of name brand stuff. Probably similar to a thrush turbo, or dynomax super turbo. Search of that part number returns them as 2" in and out. Kinda small.

In other words a subpar muffler.... whats a better diameter for exahust?

The Competition Hooker headers for 4V have a 3" collector.

Hooker headers are pretty large, free flowing headers. Unless you have a seriously modified engine, you will probably suffer a drmatic loss of low-end torque with those installed. Go for some Blackjack or Hedman headers...they work better on a street-driven, mostly-stock drivetrain. And they fit in nice and close too.

I have to very careful with my long tube headers because I only have about 3 inches of ground clearance at the tubes. I would not get longtubes for the sake of ground clearance if you will be lowering your car at all.

Great points.... looking at Headman this are the Street ones, http://m.summitracing.com/parts/hed-88320

They are also 3" at the collector.

What size exhaust do you run?

2.25 was the stock diameter. I'd run 2.5" in a performance application.

I have a pair of Hooker Comp headers with the reducers for 2.5 inch exhaust system. These are for the 4V heads and probably have about a hour run time on them. Didn't use them because I wanted a parallel running collectors and they angle inwards. Also has the O2 bung welded to the passenger side one. PM me if interested. I have a lot of parts that I will be listing in the classified section soon including a Speed Demon 750 cfm ("Mighty" version I think) that has never been installed. Starting to clean up my garage now and getting things together.

Are the Hedman 88320 for 4V heads? I dont see anything in their website about it.

I was looking at the coated version but they are very expensive, what other alternatives are out there?

Hooker headers are pretty large, free flowing headers. Unless you have a seriously modified engine, you will probably suffer a drmatic loss of low-end torque with those installed. Go for some Blackjack or Hedman headers...they work better on a street-driven, mostly-stock drivetrain. And they fit in nice and close too.

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Kit, is your opinion on Hooker headers based on the Competition ones? The problem is that it does not appear that the Hedman's are neither for 4V engines nor C6 trans. In this forum it seems that there is a lot of people liking the Hooker Comp for 4V engines, but having an issue with the ground clearance.

One question Tony, why do you want headers? There will be more underhood heat and noise, increased maintenance and minimal performance gains. The muffler (almost any muffler) will be the restrictive point in the system and negate any advantage headers may have over manifolds. Just my 2 cents worth. Many will say I'm wrong on this but offer very little proof except the proverbial "butt dyno". I'd like to see back to back dyno pulls with headers and with manifolds. I would be willing to wager there's not much diffeence.

Hooker headers are pretty large, free flowing headers. Unless you have a seriously modified engine, you will probably suffer a drmatic loss of low-end torque with those installed. Go for some Blackjack or Hedman headers...they work better on a street-driven, mostly-stock drivetrain. And they fit in nice and close too.

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Kit, is your opinion on Hooker headers based on the Competition ones? The problem is that it does not appear that the Hedman's are neither for 4V engines nor C6 trans. In this forum it seems that there is a lot of people liking the Hooker Comp for 4V engines, but having an issue with the ground clearance.

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Hooker Comp headers has pretty good clearance. Super Comp sit much lower and you have the low clearance issues. The primary tubes are larger in diameter as well as the collectors on the super comp ones.

One question Tony, why do you want headers? There will be more underhood heat and noise, increased maintenance and minimal performance gains. The muffler (almost any muffler) will be the restrictive point in the system and negate any advantage headers may have over manifolds.

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Good question. I am not concerned about noise and hopefully the temperature is controlled by having a coating. I actually want more noise. I may not have a good answer except that I have always had headers in my cars and "felt" power improvements. Most publications I have read where they dyno engines with and without show an improvement. However, I haven't read a study done with 351C-4Vs.

I can't argue if there will be a power improvement or not because I have no references, but I have this "cool" attraction for headers that I can't explain.

My biggest concern right now is the clearance issue, but I don't think there is much I can do about it. I am not planing on lowering my ride so hopefully that would help.

I am not concerned about noise and hopefully the temperature is controlled by having a coating. I actually want more noise.

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hello;
unfortunately the factory ceramic coating on headers is useless for reducing engine temps . . two of the best temp reducers are header wrap or professional heavy ceramic coating which is white . . not very appealing to the eye.

Hooker comps (not super comps) for 4V heads are what I am running. I had mine ceramic coated locally after they had been on the engine-that way any modifications you make (in this instance dragging the bottoms on a bad dip lol) get coated. Locally it cost about 200 bucks at a place called Nitroplate-but I'm sure there are local places that do similar work around most major cities.

Headers are lighter than cast iron exhaust manifolds. They are cheaper than iron manifolds for Clevelands, simply because of the high failure rate of cast iron driver side manifolds. (They crack and while Cast Iron can be repaired it is neither cheap nor guaranteed for the most part)

Long tube headers are better than iron manifolds, in some respects, as the collector design and tube length should lead to effective scavenging of exhaust.

In practice this doesn't always work out. Some brands are better than others.

On a stock engine, to be used in a car for original intended purposes (Transportation) iron manifolds have advantages over headers. On performance cars used in a manner befitting them headers are my preference

unfortunately the factory ceramic coating on headers is useless for reducing engine temps . . two of the best temp reducers are header wrap or professional heavy ceramic coating which is white . . not very appealing to the eye.

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I was afraid this was going to be the case. I was wondering how much a thin coat could really do to temp. If that's the case, why pay for coated headers. I have had wrapping around headers in the past - it is ugly but functional. I would probably wrap in critical areas where to close to the starter and other parts. The other issue with wrapping is that it is thick and I can expect there will be clearance issues.

unfortunately the factory ceramic coating on headers is useless for reducing engine temps . . two of the best temp reducers are header wrap or professional heavy ceramic coating which is white . . not very appealing to the eye.

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I was afraid this was going to be the case. I was wondering how much a thin coat could really do to temp. If that's the case, why pay for coated headers. I have had wrapping around headers in the past - it is ugly but functional. I would probably wrap in critical areas where to close to the starter and other parts. The other issue with wrapping is that it is thick and I can expect there will be clearance issues.

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most good quality headers are coated these days so its hard to avoid . . stainless is the other option but again not cheap . . if the wrap causes interference problems then they are junk headers to start with . . if jba makes some they will fit but you will pay, lol.

hooker super comps probably fit the best . . if you use shorty's then look at the hedman elites . . they are nice and have very thick tubes . . the thicker the tube the less hot they will get.

buy remflex gaskets or soft aluminum gaskets

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Which mufflers do you guys use with the headers?

Which mufflers do you guys use with the headers?

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MUFFLERS ARE RATED BY AIR FLOW JUST LKIKE EVERYTHING ELSE . . IN GENERAL, ONCE THEY FLOW A SUFFICIENT AMOUNT THERE WILL BE NO MORE INCREASE IN HP SO AT THAT POINT IT BECIMES A MATTER OF HOW YOU WANT IT TO SOUND . . THE MOST OBNOXIOUS MUFFLERS IN THE WORLD ARE FLOWMASTER SINGLE CHAMBER AND THE ROUND CHERRY BOMB GLASS PACKS.

FYNOMAX AND FLOWMASTER BITH HAVE SOUND COMPARRISON VIDEOS IN YOUTUBE AND YOU CAN ALSO TYPE IN "351 FLOWMASTER" ETC., AND PULL UP PRIVATE OARTY SOUND VIDEOS.

THE STAINLESS DYNOMAX AND DYNOMAX THRUSH TURBOS HAVE A NICE BUT NOT OBNOXIOUS SOUND.