In the middle of a RB header swap , and have a couple of ?'s.
1. After removeing stock exhaust maniford , noticed 2 insert looking thingies inside exhaust ports. What are they ? Can they be removed ?
2. Also , 2 of the exaust manifold studs snapped , even after using a little bit of heat. Was wondering what alloy they are made of ? or are they hardened ? To remove the studs and replace should I heat the stud up or the area around the stud ? Anybody have experience on these issues ? Thanks in advance.

 

Those are steel inserts, held in place by roll pins in the side of the rotor housings. I would not try to remove them. If there is enough sticking out I just clamp a vise grip on really tight and give it (the vise grips) a quick rap with a hammer. Usually this is enough to break the stud loose then you can unscrew it with a vice grip or pliers. Mazdatrix has new ones.

 

how flush did the stud break off with the rotor housing?

 

On the studs I have enough to work with , bout 1/2 an inch (not snapped flush) Just wanted to know about where to apply heat if needed so I don't snap the remaining stud closer to the housing. I will try a good rap with a dead blow first. On the inserts , I was looking for a reason of why they are there. (kind of like a 5 yr old, WHY) I would have to guess because of the extreme temp's. Just asking if anybody removes them. (they look kind of restricting) thanks for the responses, this site has more info than my pee brain can handle, lol.

 

mine were removedwhen the motor was rebuilt, no problems that ive seen from not having them.

 

The inserts channel exhaust flow to drop high-freq exhaust noise, mainly.

 

There are two ways to use heat and it often depends on what you have for a torch and what kind of metal you're dealing with. Generally heat the stud up as quick and hot as you can and leave the rest of the metal as cold as you can then, hit straight inward on the end of the stud/bolt then let it cool. Put some good lube on it then clamp the vise grips on as tight as you can get and rock them back and forth, in and out till it starts to move. Never turn so hard to let the vise grips slip. What happens is the stud tries to expand but can't and when it cools it shrinks a bit. The hitting inward loosens the threads.
If that won't work try heating the whole area up and then hit in again and try to remove it with it still hot. Rocking back and forth and trying to get some lube in there is the trick to the tough ones.

Tips: Never twist so hard that it slips or breaks off. Steel hammer is way better than a dead blow. If you can't do it with it sticking out you won't be able to do it with it flush and it'll make it 100x tougher for the guy you get to do it for you.

 

Interesting , I called RB and was told the inserts or sleeves helped keep exhaust temps down on the housings. Hmmm , 1 question , 2 different answers.
I'll keep digging.

 

It depends on what inserts you're talking about... There are two different types. The main insert is what racing beat was talking about. Driven was refering to exhaust difusers that were attached to the inserts installed in all 86-92 NA 7's.

 

best to leave the inserts in place.

 

Simplest trick I've seen to removing studs is to heat redhot, then quench with a ball of beeswax. As soon as that's done, wrench out.

 

you can also run to sears and grab a set of these rounded bolt extractors. you hammer the extractor onto the stud or rounded bolt and out a socket or a wrench over the extractor and turn counterclockwise and the extractor will bite into the stud and will remove it as if it had a head on it. may want to heat and cool prior to this or apply heat to the surrounding area to expand it. not too much heat though, remember it's aluminum we're talking about here:

 

...and for the replacements, use Pineapple Racing's copper exhaust nuts. Supposed to be MUCH more resistant to heat and corrosion so everything will buzz off tickety-boo next time you need to remove them...
Stu Aull
80SG
Alaska