HyFive578

iTrader: (3)

[QUOTE=neva satisfied;4030012]It's true that the Gen-X headers have the "cool collar" design where the outer tubes taper about 1/4" before the flange and it's true that older style headers had the outer tubes run all the way to the flange but just because the headers have the cool collar design doesn't mean they are OK.

The headers that failed on me where "newer design" with the cool collars but were from the vintage (2004) where the grade of stainless was inferior and CMI was not heat treating the headers. From what I've been told, it wasn't until 2010 that the headers that CMI made for Merc as OEM were improved.

You can tell a Gen-x header because it looks nothing like a CMI/Merc OEM header. It has separate distribution tubes that attach to the header with small rubber hoses and there is no bypass hose between the distribution tubes and tails. The Gen-x header is better quality overall than the CMI/Merc header.

PARADOX

Pretty much everyone knows I had some "issues" with CMI's, Merc. and their staff, etc. A few things for everyone with CMI's.
The "cool" collar is just a way to make them easier to fabricate, weld. A weak point, no cooling at the flange and the single layer of tube. (+- 1/4" to 1/2" ) Often racks. The collectors are weak and vibrate and crack.
A few things you can do to help. Drain the headers after "Every" use, but wait for about 20-30 minutes to allow the system to cool. Draining them too quick, (IE; the after market constant drain) will drain the headers as soon as the engines are shut off. Headers will remain hot and may crack. Install a "heavy" duty rubber connection from the tail pipes to the tips, with the wire inserts. This will help stiffen the headers. You want to remove any movement of the headers. Install a connection rod, (like the outdrive tie rods, ) between the port and strbd headers on the top. This will reduce
flapping" just thing if you have your arms out and jump off from a chair, your arms will come down a bit, The headers will do the same. YOu want the headers to "move" with the motors and not independently. Movement = cracks and stress. At the cool collar and the flange, you can weld or install some "grill" like SST parts to help cool the gap. Kinda like air cooled bikes or outboards, or have some one else some "connecting" beads from the flange to the outside tube. Spread the heat. Even wrapping Al foil around will help, to decapitate the heat. I got my set up like this and for several yeas no issues. I had leaky headers, valve issues but luckily I caught the problem in time so valve work was my most costly item. Check for compression and leak down OFTEN. Hope this helps. (until my header design gets to the market. )

PARADOX

[QUOTE=HyFive578;4030038] The "rubber" hose system is CMI, the solid water connection is Merc. The gen "X' headers have "turned down" area at the collector box to avoid back splash. With the square collection box, the lower tubes will allow water to the cylinders. or back wash from waves. Actually this came after I had some serious discussions with the CMI dudes.

gnorthga

Thanks but i already have a used set that are repaired

my builder said i need new ones

HyFive578

iTrader: (3)

Are you talking about the gen-x headers or CMI/Merc headers?

gofastlvr

Can't even buy them from Merc anymore... Buying new ones from Teague would be my suggestion. They are still $5400 retail a set! ching ching Gerald!!!!!

I bought a new set of Big Tubes last year so just bend over and take it brother... MG told me being cool aint cheap!

the deep

iTrader: (8)

Take a look at these . http://www.diamondperformanceparts.c...cat=280&page=1

Somethin' Sexy

Is it just me, or is anyone else tired of the crap prdoucts that Mercury Racing puts out? 1350's,1100's, drive failures, including #6's, for no apparent reason, 525, 600, 700 header issues. The only decent reliable product that they put out was the 496 and 525 (minus the headers), which is why I believe they have discontinued production of these.

How they can cram a motor into an outboard casing and it be more reliable is beyond me. Maybe the fisherman ***** more than we do.

You would think after 50 years, they could get it right.

Although the header was a Mercury spec, I also blame CMI for allowing these to go to production. They had to know the header was inferior. Kinda of like hiring a roofer to plumb my house...

PARADOX

The gen x headers have the collectors boxes with a low lip to help with the back wash. It's like a little dam before the water goes into the tubes. Not sure how the "current" merc headers look like.

ratman

look at the stainless marine stuff, it last forever from what ive seen