Exhaust Stud woes: Longer barrel nuts? 12mm Copper nuts? Options?

[RichPugh]

Just test fitting my heat exchangers on my 3.0 SC engine (914-6 swap project) and the new barrel nuts I have: A. Don’t fit thru the access holes in the heat exchangers and, 2: Are too short to tighten down the flange to the head.

The manufacturer of the heat exchangers said long exhaust studs are a common issue and that some barrel nuts are thinner than others so perhaps I have the perfect *****storm.

Do I need shorter studs? Are there notable longer and thinner barrel nuts? Can I just use standard copper 12mm nuts and thread them all the way down?

[boyt911sc]

Rich,

You need to use or find the correct barrel nuts for your set-up. First, you need the right outside diameter barrel nuts to get through the access hole. Second, depending on the length of the exposed exhaust studs, use or find the appropriate barrel length. You need to do some measurements to determine what barrel nut length and OD you need for your set up.

Tony

[lsf911]

Are the heat exchangers the thick flange version? Later 3.0SCs require the thick flange and therefore have longer studs.
If you are using thin flange then you need the shorter studs.
I was unaware of the smaller diameter barrel nuts. Good to know.

[RichPugh]

What I am quickly learning is the studs on my engine are for thick flange heat exchangers and the aftermarket heat exchangers I have are thin. So... swapping studs isn’t that daunting (although I’d rather not) so... I don’t think there are barrel nuts long enough to work with these long studs for thin flange heat exchangers. Blaaahh!!!

[mepstein]

Rich - I have Ben's HE's on a 3.2 engine. Here's what I did. I superglued some spacers to the barrel nuts. Ben sent me a couple spacers but he said they can ordered online. I poked the allen wrench up through the hole, put the nut on the wrench and tightened it down. The barrel nuts actually fit through most of the holes but a couple had enough welding bead to catch it at some point. The studs that are not accessible with barrel nuts get regular exhaust nuts. You use a distributor wrench/SSi wrench to tighten. I wouldn't use regular nuts throughout because they are a pain to install and remove and you might have to remove and replace the HE's more than once as you assemble your car. Hope this helps. Mark

I would rather use spacers than swap studs and risk breaking one or more.

[john walker's workshop]

+ for spacers. 3.2 intake barrel nuts have a smaller OD.

[shamrok]

I'd probably just run 12mm copper nuts and not mess with the studs.

[mepstein]

Originally Posted by john walker's workshop

+ for spacers. 3.2 intake barrel nuts have a smaller OD.

Good to know. Thanks

[piscator]

Belmetric should have what you need and they're great to work with if you call with a specific problem. Family business, very knowledgeable people.

https://www.belmetric.com/metric-copper-exhaust-nuts-c-3_51/

[Jack Stands]

Running copper nuts may be a good idea, but may be neigh impossible to access with heat exchangers. Barrel nuts are nice, but obviously must fit through the access holes in the heat exchangers and be long enough to clamp the flange. Spacers seem like a nice idea if needed, and I imagine the barrel nuts could have the OD machined down if you can’t find narrower ones.

[shamrok]

The 12mm copper nuts from Belmetric fit thru the access holes if you use 1/4” sockets. For the others, a 12mm offset wrench works well.

[Flat6pac]

I’ve had success with JIS 12mm nuts and snap on 1/4 drive 12 going through the access holes
Bruce

[RarlyL8]

Our headers come standard with removable spacers so they can be used with either thick or thin flange port studs. They pop off with a screw driver.





If you'd like a set shoot me an email, we have plenty of them.

[RichPugh]

Originally Posted by RarlyL8

If you'd like a set shoot me an email, we have plenty of them.

Thank you, that would be great. Whats your email? I think spacers will be the quickest fix. Hope they're thick enough.

In the event I do swap the studs to the shorter ones, this may be a stupid question but, I only see two stud options... 37mm and 46mm. Are the ones I have the 46mm and I need the 37mm? What is the thickness of those spacer?

[john walker's workshop]

Just do the spacers. Even professionals don't like stud replacement much. Don't say you weren't warned.

[RichPugh]

Originally Posted by john walker's workshop

Just do the spacers. Even professionals don't like stud replacement much. Don't say you weren't warned.

Sage advise. I'm gonna grab those and a new ball-socket hex and hope for the best. Worst case without swapping studs, I can get thick flange headers, LOL.

[RarlyL8]

Service at MKExhaust.com
Yes drilling out snapped studs is no fun, let sleeping dogs lie.

[911pcars]

I think the suggested copper-coated nuts are M8 with a 12mm hex.

Long studs are not a problem. Spacers, washers are valid solutions. Liberally use anti-seize. E

[RichPugh]

Originally Posted by 911pcars

I think the suggested copper-coated nuts are M8 with a 12mm hex.

Long studs are not a problem. Spacers, washers are valid solutions. Liberally use anti-seize. E

My issue with the 12mm copper coated nuts is I don't think I'll be able to get even a wobble socket on them thru the heat exchanger access holes... so... might have to improvise with some custom tool bending I'll see if the barrel nuts work once I get the spacers. If they're still not spaced out enough, I can either get bigger spacers or try to run the copper coated nuts. I'll get em on there! Thanks everyone.

[john walker's workshop]

ya know, you can use the wider barrel nuts by holding them with your fingers over the studs, then stick your long 8mm allen tool down the exchanger holes....