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Eleventeenth Gear Poster
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First, if your gonna say…“You should of bought Kooks ya dumbass”…save it. I personally don’t feel like spending $700 on my car for headers at this point. If/when I go all out on the car, when it’s not a daily driver, and put down the money for an SC, then I’ll get some Kooks. Until then I am willing to take the risk of these cracking somewhere down the road. I consider this a learning experience and I’ll leave it at that :)

I bought a pair of the ssautochrome, wanna be JBA, headers off eBay for $95 shipped to my door. I plan to modify them to help prevent them from cracking and would like input from those who have had their JBAs crack on them. On the passenger side I know the welds on last cylinder like to crack, and that’s the only crack that I have seen mentioned. Do they crack anywhere else? Besides rewelding that area, what else could be helpful? Possibly some additional bracing? Also, I have read that having the face of the headers milled flat would be helpful as well and plan to have that done as the very last step. Any positive input will be helpful; also any tips/suggestions on the best way to weld these without causing a lot of warpage or additional damage would be helpful as well. I hope to have them torqued down to a 4.6 head when they are welded. Thanks.
 

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i just got a set of those too from ebay and put them on last week along with a flowmaster catback. before i put them on, i had the face milled down so the chrome was gone so it would adhere to the gasket better. that's about all i did to mine and i'm pretty pleased at the results i got. there's definately more power there. i guess i also got rid of the chrome on the end of the collector as well.
 

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Check with Chadg, his JBA's cracked, and Blake-Vortec recently posted that his blew out so badly, his car is down and out and he's goin back to stock manifolds. Contact them, for starters..

Good luck with your project. Buying something, even cheaply, that you know in advance is gonna break, then spending 6 or so hours putting them on your car, only to have to replace them down the road and actually telling everyone that you are doing it is a gutsy move. :D

It appeared from the pictures I saw of those headers that the primary ports are a bit smaller than the ports on the heads, and someone posted that as fact, perhaps you can confirm or dispell that notion, when you do the install.

Just before I left Moroso the other night, you nailed your dial-in right on the money. Good job... (we won't talk about the color of the light ;) )... Are you planning on getting your 3.73's installed anytime soon??? if so you're gonna have to make some dial-in adjustments on the 30th....
 

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They may hold up on a n/a car. Mine cracked,chad,Mike Siska,danners,richardm
We all have or had blowers on our, May be the stress from the power or the high egt temp. For 95 bucks worth a shot. They crack across the top of the collector Good luck
 

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Did Chad's crack before, or after the blower??? I know he added "Did your JBA's crack today?" to his sig, but don't remember when....
 

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Mine cracked before I ever had a blower, so did Dan's.
 

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kdanner said:
Mine cracked before I ever had a blower, so did Dan's.
Okay, I think this was mentioned before and I was wondering if anyone went anywhere with it...

Someone mentioned putting a short piece of flex pipe after the headers (or I suppose it'd be best after the cats if applicable) to account for any flex between chassis/exhaust/engine that would put strain on the headers. Granted they shouldn't crack in the first place, but wouldn't this still be a solution?
....or is there "warpage" per se in the header it's self that causes the cracking?

And goldbird, chad's cracked after the blower....

-jw
 

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Send them out to a head shop and get them to run them over their belt sanding table so they are atleast close to flat. Second be sure when you bolt up the exhaust to them you don't put stress on the headers. I used a couple of SS flex couplings when I did mine. If you want to PM me your e mail I'll send you a picture of them.
 

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It sounds like the cracking is mostly because of the headers themselves trying to pull apart when they are heated up, then cooled down, ad infinitum. Maybe its not enough bracing. (too loose?) Maybe the headers don't have enough internal stress relief built in. (too stiff?) Maybe the tubing is bad. I dunno. I'm no forensic metallurgist.
 

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Sounds like if he figures out a way to prevent JBA's from cracking, he oughtta patent it, and sell the patent to JBA.

Certainly passing it on to others here would be most beneficial...
 

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I am not sure that the exhaust temperature would cause the problem. Sounds to me more like it can be an exhaust gas flow issue. The forces generated by the gas flow can increase stress. I would assume that under a certain HP number we have seen no failures. I am curious if anyone knows what the lowest horsepower some had on their car where the headers cracked?

Once the exact cause is identified and made repeatable a solution can formulated. A fix may be as simple as selecting a better grade of material, adding more metal in certain places, slight changes in the collectors to distribute the stress better.
 

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96 GoldBird said:
Sounds like if he figures out a way to prevent JBA's from cracking, he oughtta patent it, and sell the patent to JBA.
Aaron, I think we better find a way to fix these things. :D

When you get them in, see if a magnet sticks to em.
 

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J.Miller said:
The forces generated by the gas flow can increase stress. I would assume that under a certain HP number we have seen no failures. I am curious if anyone knows what the lowest horsepower some had on their car where the headers cracked?

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Sorry but not a chance. The exhaust pressure is minimal even in a blowen car.
The reason we see so many cracked JBA headers is it the ONLY header we see
that has been on a MN12 for more than a few months. Oh and yes the quality of them is poor. Go to a Mustang board or a Camero board and look around
you will see that all makes of headers crack ...............period. Just wait till we start seeing cracked Kooks.
 

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I gotta believe it is the rapid extreme temperature changes in combination with vibration and the torque of the engines on the mounts, NOT exhaust pressure that causes failure.

While it is true that all makes of headers crack, not every single header sold by most companies fail. In the time I have cruised this site, I have not seen anyone stand up and say that their JBA's didn't crack. I am sure that there are some out there, but they certainly seem to bee the silent minority.

Kooks has been making headers for many cars, for many years and I am sure they have had their failures, and I expect some of the MN12 Kooks headers will someday fail, I only hope that Kooks success rate and and reputation with the other headers they make carries over into ours.... you are right though, only time will tell..... But you can sure see the difference in the quality of manufacture, that's gotta improve the odds....
 

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The Kooks are a very good header and they may not break...................but I have heard of kooks breaking before. Bottom line is if you don't get the JBAs or SSA autochrome headers re machined they WILL break. The flanges are not flat.
If you get them machined they MAY last a while. I know it's stupid to have to machine a new header but that life.
 

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I think we know it's always in the same spot that they crack? If so, then we can examine the design. I bought a set of used JBA's from Don Teeple and his were cracked on the passenger side header on the shortest tube that is closest to the collector.

The design of a header in general leads to possibility of cracks or breaks. I believe this is why Ford got away from headers or tubular manifolds like they used on the 5.0L Mustangs. They couldn't afford the idea of all them exhaust leaks nor did they have enough room on most cars to design a proper header.

So we have to look at the problems on the JBA MN12 design itself. 1) Do other JBA headers crack? I find it hard to swallow that JBA could get away with this. I mean they offer headers for the Mustang 3.8L/5.0L/4.6L and Cobra. Corvette, Camaro, Firebird, and more. Do they have this problem? I doubt it but I haven't done enough research.

The MN12 JBA headers are UNEQUAL length so each tube is just long enough to reach it's destination. The longer tubes have a chance to move more than the shorter tubes. The 3/8" thick laser cut flange should be enough to secure the header to the gasket and block. I don't think there is movement there.

I know many people have tried different gasket materials. Some used the crushable Ford exhaust manifold gaskets while others used Percy's. I have to rule this out as well.

So what are we left with? We have the shortest tube of the entire bunch doesn't even go into JBA's "FIRECONE COLLECTOR" from the same angle as the others. Its all by itself and enters from almost the side of the collector. Then the EGR tube exits right after it. So you basically have a giant weld holding two tubes to a collector. Factor in the movement of the material (hot/cold), the exhaust movement and engine movement and you have a recipe for disaster.

I believe this is why they started cutting the flange and using the brace. The JBA's I have must be old since they do not have the cut flange nor the brace. Yet, I hear even that didn't help as they are still cracking. So my theory is they will all crack just based on the nature of their design. I don't think there is a way to stop it.

A-Train
 
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