cracked exhaust stock manifolds, T/F

[buzzardB]

Is it true that most jeeps have headers because stock manifolds tend to crack? My old Black Jack header on the drivers side is a pain. Difficult to even touch the clutch linkage and/or the brake block, and both sides make spark plug changes tough.

 

[mriplaybass]

I've never heard of manifolds just randomly cracking. Our Jeep had headers on it when we bought it, and I took them off and replaced them with stock manifolds. No problems in 3 years.

 

[JeffP]

Is it true that most jeeps have headers because stock manifolds tend to crack? My old Black Jack header on the drivers side is a pain. Difficult to even touch the clutch linkage and/or the brake block, and both sides make spark plug changes tough.

The only Jeeps I’ve had with stock manifolds were ones I bought new or the military 4 cyls. AMC 258 i6 / 4.2l I6 headers seem OK, but the V8 headers are a PITA! The only way I’ve found to quiet them down is with Flowmaster mufflers and the longest pipe I can put on. Still too loud for my liking.
Don’t take me wrong, it’s great to embarrass the jerk on the street with his hotrod... getting his doors blown off by a Jeep. But out on the trails it gets old real fast.
There might be something to your question... stock manifolds are hard to come by.

 

[Posi]

I would absolutely take my AMC stock exhaust manifolds on my V8 over headers. Less heat, and the AMC V8 manifolds breath well.
The AMC stock V8 exhaust manifolds are easily found on ebay.

https://www.ebay.com/i/323300240035?chn=ps

 

[Torxhead]

The earlier 4 liter engines that came in the Wranglers and Grand Cherokees had a history of the exhaust manifold cracking. I had a '96 Grand w/4.0 with a cracked manifold. When guys would replace them with headers it made for an excessive amount of underhood heat.

 

[JeffP]

The earlier 4 liter engines that came in the Wranglers and Grand Cherokees had a history of the exhaust manifold cracking. I had a '96 Grand w/4.0 with a cracked manifold. When guys would replace them with headers it made for an excessive amount of underhood heat.

Seems like heat could be reduced or eliminated by wrapping the tubes. Similar to what is done on some helicopters.
I wrapped part of a header on a Ford to reduce heat getting to the starter. Amazing the wrap (on the outside) is the same as ambient temperature no matter how long or hard the engine has run.

 

[PistolDave]

I've never really understood the header thing on jeeps or any other vehicle that makes under 250 horsepower. It's one of those modifications that people swear up and down makes 100 more horsepower, but if you don't change the intake, cam, carb, etc. I think you are wasting your time, and this can and has been proven on the dyno. Headers make sense on a 12:1 small block v8 with a hot cam, but on a AMC 258 i6 / 4.2l or AMC 304 with stock intake, cam, and 8:1 compression they are beyond unnecessary.

 

[DaveMueller]

I wrapped part of a header on a Ford to reduce heat getting to the starter. Amazing the wrap (on the outside) is the same as ambient temperature no matter how long or hard the engine has run.

Remember the brand? Happy with the results?

I'm redoing my exhaust and don't have any heat shields, I was thinking of wrapping a few key spots.

 

[jp360cj]

Don’t take me wrong, it’s great to embarrass the jerk on the street with his hotrod... getting his doors blown off by a Jeep. But out on the trails it gets old real fast.

Absolutely. I'm running a cheap set of headers (Summit fenderwells) and sidepipes (4WD Hardware glasspacks) and it gets old on the trail and on long drives. I put them on when I was a broke college student doing a V8 swap. They were cheap and easy, and I do sound great. Now that I'm a little bit older, they still sound great riding around town, but I plan to quiet it down soon, probably a winter project. Plan to go with stock manifolds, and some sort of muffler out the back corner.

 

[shum8]

I would absolutely take my AMC stock exhaust manifolds on my V8 over headers. Less heat, and the AMC V8 manifolds breath well.
The AMC stock V8 exhaust manifolds are easily found on ebay.

https://www.ebay.com/i/323300240035?chn=ps

Funny - that seller is about 30 minutes from me.......

 

[Posi]

Besides eBay, you can find stock manifolds in the link below as well.

VintageJeepParts.com - Search Results for "V8 exhaust manifold "