Dorman Exhaust Manifold Bolts for 5.7 Hemi

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Taspeace

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Do any of you 5.7 Hemi owners have experience with using Dorman exhaust manifold bolts? They make three types, two sets (one of which is black, and the other one "clear") are strength rated as 10.9. The third type is made from stainless steel and the bolts are rated at 8.8. Even though stainless has the lower strength rating the website says that the stainless version was created to end bolt failures on our 5.7s, . Apparently, corrosion due to the dissimilar metals of the aluminum block and the iron exhaust manifold contributes significantly to why the manifold bolts consistently break.

I had hoped to use American Racing Product bolts, but when I called them, they said they don't make manifold bolts specific to the 5.7 Hemi.

Thanks in advance for any tips you have to offer.
 

EdGs

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I used a set of everbuilt exhaust manifold bolts from Amazon. No issues at all.

I used Fel-Pro gaskets, but have heard the Remflex are even better.

Have your exhaust manifolds machined flat as well, and you should not have a breakage problem again.
 
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Taspeace

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A follow up: I did some research on stainless steel bolts and quickly found out that there are too many unknowable variables to be certain of how they'll perform before actually trying the things. For example, the range of hardness and tensile strength of both "ordinary steel" and stainless steel vary tremendously and overlap quite a bit. That means you can get stainless bolts that are harder, "stronger" than ordinary steel and won't rust, or you might pay the extra $ for stainless steel and get a bolt that is softer, "weaker", and yes, can even rust and respond to magnatism. It all comes down to the bolt's carbon and chromium content and how the metals are processed. Of course, Dorman doesn't specify any of that. They only specify that the bolts are satinless steel. However, judging by the hardness rating and their comments about rust and corrosion resistance, I am SPECULATING that what Dorman did was to go with a bolt that is significantly harder than the OEM bolts but softer than their own "ordinary steel" bolts, and far more resistant to rust and corrosion. I called the company and their tech support person said that they are getting excellent results from the stainless bolts and that they also offer a line of stainless bolts for some Ford products that are known to break manifold bolts. At $43.95 (per side) on Ebay, the Dorman stainless bolts (part number 03309HP) look like what I'll use in combination with Ramflex gaskets and LA-CO nickel grade antiseize paste to, hopefully, end my exhaust leak issues for at least the next 100,000 miles. I'll also change the bolts and clips that join the manifold to the down tube while I'm in there.
 

RodRamCar

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Yeah honestly, the manifolds being machined flat (since they've already had the heat cycles on them), new gaskets and some new/better bolts seems like the most cost efficient way to go unless you don't care and go to some LTHs.
 

blackbetty14

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The bolt breakage is not going to be fixed with SS bolts. The issue is the warping of the thick @$$ manifold which pulls the bolts/studs and pops them. If they went with a large than M8 fastener it might be ok but they are rather small for the application. Ford and GM LS has the same issue and use the same M8 fastener. Now I don't believe a dissimilar metal as a real reason. Grade 10.9 or 12.9 are harder/tougher bolts but they don't stretch as much as a 8.8 so I think the SS bolts are soft and will stretch more before they break. I think its a design flaw and undersized hardware plus the weight hanging off the back of those things is a lot. You can try the SS bolts but I would machine flat the stock manifolds and use remflex gaskets over stock as that's your best shot with OEM style. Or fix the issue with headers, remflex gaskets and ARP SS hardware which are better than grade 12.9. I do however think that downgrading to grade 8.8 isn't a smart move given how the stock bolts fail plus your still doing dissimilar metals in the head. I always use Nickle anti seize on anything exhaust related (not copper or aluminum anti seize).
 
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Taspeace

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Having gone to the Remflex website and read about the "pure carbon" design concept with 50% crush factor and a 3,000 degree heat rating, I'm thinking that they're probably a significant step above the Fel-Pro gaskets, though those were the best you could get for a long time.
 

blackbetty14

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Having gone to the Remflex website and read about the "pure carbon" design concept with 50% crush factor and a 3,000 degree heat rating, I'm thinking that they're probably a significant step above the Fel-Pro gaskets, though those were the best you could get for a long time.
I run them on all my hotrods and they are boosted (turbo and supercharger) and never had a leak or a blowout. They are the best hand down, and I've measured my pre turbo backpressure and its been as high as 40psi from the turbo to the head at 1500+*F and not one issue. I did run the remflex on my ceramic coated stock ram exhaust manifolds and they were warped like .060" and I didn't have a manifold bolt snap. MY theory is they will offer more crush before they snap the bolts so they have to warp alot before the bolts are under enough tension to snap. The stock gaskets/felpro are kinda junky as they are just a SS heat shield and a very thin cheap graphite gasket rivited to it. I thought about taking the shields and removing the rivets and using with the remflex but then the remflex won't seal against the head surface.
 
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